Which cells are not capable of phagocytosis? Phagocytosis: who wins? The phagocytic reaction is performed

Phagocytosis is the body's defense mechanism that ingests particulate matter. In the process of destroying harmful substances, waste, toxins, and decomposition waste are removed. Active cells are able to detect foreign tissue inclusions. They begin to quickly attack the aggressor, splitting it into simple particles.

The essence of the phenomenon

Phagocytosis is a defense against pathogens. Domestic scientist Mechnikov I.I. conducted experiments to study the phenomenon. He introduced foreign inclusions into the bodies of starfish and daphnia and recorded the results of his observations.

The stages of phagocytosis were recorded through microscopic examination of marine life. Fungal spores were used as the causative agent. Having placed them in starfish tissue, the scientist noticed the movement of active cells. The moving particles attacked again and again until they completely covered the foreign body.

However, after exceeding the amount of harmful components, the animal was unable to resist and died. The protective cells are given the name phagocytes, consisting of two Greek words: devour and cell.

Active particles of the defense mechanism

The action of leukocytes and macrophages is distinguished as a result of phagocytosis. These are not the only cells guarding the health of the body; in animals, the active particles are oocytes, placental “guardians”.

The phenomenon of phagocytosis is carried out by two protective cells:

• Neutrophils - created in the bone marrow. They belong to granulocytic blood particles, the structure of which is distinguished by its granularity.
• Monocytes are a type of white blood cell that come from the bone marrow. Young phagocytes have great mobility and construct the main protective barrier.

Selective protection

Phagocytosis is an active defense of the body, in which only pathogenic cells are destroyed, useful particles pass the barrier without complications. Quantitative assessment through laboratory blood tests is used to analyze the state of human health. An increased concentration of leukocytes indicates an ongoing inflammatory process.

Phagocytosis is a protective barrier against a huge number of pathogens:

• bacteria;
• viruses;
• blood clots;
• tumor cells;
• fungal spores;
• toxins and slag inclusions.

White blood cell counts change periodically; correct conclusions are drawn after several general blood tests. So, in pregnant women the amount is slightly higher, and this is a normal state of the body.

Low rates of phagocytosis are observed in long-term chronic diseases:

• tuberculosis;
• pyelonephritis;
• respiratory tract infections;
• rheumatism;
• atopic dermatitis.

The activity of phagocytes changes under the influence of certain substances:

• cholesterol;
• calcium salts;
• antibodies;
• histamine.

Avitaminoses, the use of antibiotics, and corticosteroids inhibit the defense mechanism. Phagocytosis assists the immune system. Forced activation occurs in three ways:

• Classic - carried out according to the antigen-antibody principle. Activators are immunoglobulins IgG, IgM.
• Alternative - polysaccharides, viral particles, tumor cells are used.
• Lectin - applies to a group of proteins that pass through the liver.

Particle destruction sequence

To understand the process of the defense mechanism, the stages of phagocytosis are defined:

• Chemotaxis is the period of penetration of a foreign particle into the human body. It is characterized by abundant release of a chemical reagent that serves as a signal for activity for macrophages, neutrophils, and monocytes. Human immunity directly depends on the activity of protective cells. All awakened cells attack the area where the foreign body has been introduced.
• Adhesion is the recognition of a foreign body due to receptors by phagocytes.
• Preparatory process of protective cells for attack.
• Absorption - particles gradually cover the foreign substance with their membrane.
• The formation of a phagosome is the completion of the surrounding of a foreign body by a membrane.
• Creation of a phagolysosome - digestive enzymes are released into the capsule.
• Killing - killing harmful particles.
• Removal of particle decomposition residues.

The stages of phagocytosis are considered by medicine to understand the internal processes of the development of any disease. The doctor must understand the basics of the phenomenon to diagnose inflammation.

For various reasons.

Some cells can use various methods, such as ion pumps or osmosis, to move macromolecules as well as chemicals across the plasma membrane and cytoplasm. But large particles, such as , are too large to use small channels for transport across the cell membrane. To absorb larger particles, cells use a process called . There are several different types of endocytosis, one of which is called phagocytosis.

What is phagocytosis?

Phagocytosis is a process in which a cell binds to a desired particle on the surface, and then envelops and immerses it inside. The process of phagocytosis often occurs when a cell attempts to destroy something, such as a virus or an infected cell, and is often used by cells of the immune system.

Phagocytosis will not occur unless the cell is in physical contact with the particle it wants to engulf. Cell surface receptors used for phagocytosis depend on. These are the most common ones:

• Opsonin receptors: are used to bind bacteria or other particles that have been coated with immunoglobulin G (or IgG) antibodies by the immune system. The immune system coats potential threats in antibodies so that other cells know to destroy them. Also, the immune system can use a group of complex proteins to tag bacteria called the complement system. The complement system is another way the immune system destroys threats to the body.
• Scavenger receptors: bind to molecules produced by bacteria. Most bacteria and cells produce a matrix of proteins surrounding themselves (called an "extracellular matrix"). The matrix is ​​an ideal way for the immune system to identify foreign species in the body, since human cells do not produce the same protein matrix.
• Toll-like receptors: receptors, named after a similar receptor in fruit flies, encoded by the Toll gene, that bind to specific molecules produced by bacteria. Toll-like receptors are a key part of the innate immune system because, when associated with a bacterial pathogen, they recognize specific bacteria and activate an immune response. There are many different types of Toll-like receptors produced by the body, all of which bind different molecules.
• Antibodies: some immune cells produce antibodies that bind to specific antigens. This is a process similar to how similar receptors recognize and identify what type of bacteria is infecting the host. Antigens are molecules that act as a pathogenic "calling card" because they help the immune system understand what threat it is dealing with.

How does phagocytosis occur?

To carry out the process of phagocytosis, cells must perform several sequential actions. Keep in mind that different cell types perform phagocytosis differently.

• The virus and the cell must come into contact with each other. Sometimes an immune cell accidentally picks up a virus in the bloodstream. In other cases, cells move through a process called chemotaxis. Chemotaxis means the movement of a microorganism or cell in response to a chemical stimulus. Many immune system cells move in response to cytokines, small proteins used specifically to transmit signals within the cell. Cytokines signal cells to move to a specific area of ​​the body where a particle (in our case, a virus) is detected. This is typical for infections in a specific area (for example, a skin wound infected with bacteria).
• The virus binds to receptors on the cell surface. Remember that different cell types express different receptors. Some receptors are general, meaning that they can identify a spontaneous molecule versus a potential threat, while others are very specific, such as similar receptors or antibodies. The macrophage does not initiate phagocytosis without successful binding of cell surface receptors.
• Viruses may also have virus-specific surface receptors on the macrophage. Viruses must gain access to the cytoplasm or host cell to replicate and cause infection, so they use their surface receptors to interact with cells of the immune system and use the immune response to enter the cell. Sometimes, when a virus and a host cell interact, the host cell can successfully destroy the virus and stop the infection from spreading. In other cases, the host cell ingests the virus, which begins to replicate. Once this happens, the infected cell is identified and destroyed by other cells of the immune system to stop viral replication and spread of infection.

• The macrophage begins to rotate around the virus, absorbing it into its pocket. Instead of moving a large element across the plasma membrane, which could damage it, phagocytosis uses invagination to trap the particle inside, enveloping it around it. Invagination is the action of folding inward to form a cavity or pouch. The cell traps the virus inside, creating a pocket without damaging the plasma membrane. Remember that cells are quite flexible and fluid.

• The captured virus is completely enclosed in a vesicular structure called a "phagosome" within the cytoplasm. The lips of the pocket, formed as a result of intussusception, are pulled together to close the gap. This action creates a phagosome, where the plasma membrane moves around the particle, placing it safely inside the cell.

• The phagosomes fuse with, becoming a "phagolysosome". Lysosomes are also vesicular structures similar to phagosomes that process waste within the cell. To better understand the functions of the lysosome, the prefix "Lyses" means division or dissolution. Without fusion with the lysosome, the phagosome is unable to do anything with the contents inside.
• The phagolysosome lowers the pH to destroy its contents. A lysosome or phagolysosome is capable of destroying the substance inside itself, sharply reducing the pH of the internal environment. The decrease in pH makes the environment in the phagolysosome very acidic. This is an effective way to kill or neutralize whatever is inside the phagolysosome to prevent the cell from becoming infected. Some viruses actually use the reduced pH to escape the phagolysosome and begin replicating inside the cell. For example, influenza uses a decrease in pH to activate a conformational change that allows it to escape into the cytoplasm.
• After the contents have been neutralized, the phagolysosome forms a residual body that contains waste from the phagolysosome. The residual body is eventually eliminated from the cell.

Phagocytosis and the immune system

Phagocytosis is an important component of the immune system. Several types of immune system cells perform phagocytosis, such as neutrophils, macrophages, dendritic cells, and B lymphocytes. The action of phagocytic pathogenic or foreign particles allows immune system cells to know what they are fighting. Knowing the enemy, immune system cells can specifically target similar particles circulating in the body.

Another function of phagocytosis in the immune system is the engulfment and destruction of pathogens (such as viruses or bacteria) and infected cells. By destroying infected cells, the immune system limits the rate at which the infection spreads and multiplies. We mentioned earlier that the phagolysosome creates an acidic environment to destroy or neutralize its contents. Immune system cells that perform phagocytosis may also use other mechanisms to kill pathogens within the phagolisome, such as:

• Oxygen radicals: highly reactive molecules that react with proteins, lipids and other biological molecules. During physiological stress, the amount of oxygen radicals in the cell can increase dramatically, causing oxidative stress, which can destroy.
• Nitric oxide: a reactive substance similar to oxygen radicals that reacts with superoxide to create additional molecules that damage various types of biological molecules.
• Antimicrobial proteins: proteins that specifically damage or kill bacteria. Examples of antimicrobial proteins include proteases, which kill various bacteria by destroying essential proteins, and lysozyme, which attacks gram-positive bacteria.
• Antimicrobial peptides: are similar to antimicrobial proteins in that they also attack and kill bacteria. Some antimicrobial peptides, such as defensins, attack bacterial cell membranes.
• Binding proteins: are important players in the innate immune system because they compete with proteins or ions that might otherwise be beneficial to bacteria or viral replication. Lactoferrin is a binding protein found in mucous membranes and binds iron ions necessary for bacterial growth.

Immune status, phagocytosis (phagocytic index, phagocytic index, phagocytosis completion index), blood

Preparation for the study: No special preparation is required; blood is taken from a vein in the morning, on an empty stomach, into tubes with EDTA.

Nonspecific cellular defense of the body is carried out by leukocytes, which are capable of phagocytosis. Phagocytosis is the process of recognition, capture and absorption of various foreign structures (destroyed cells, bacteria, antigen-antibody complexes, etc.). Cells that carry out phagocytosis (neutrophils, monocytes, macrophages) are called by the general term phagocytes. Phagocytes actively move and contain a large number of granules with various biologically active substances. Phagocytic activity of leukocytes

A leukocyte suspension is obtained from the blood in a certain way, which is mixed with the exact amount of leukocytes (1 billion microbes in 1 ml). After 30 and 120 minutes, smears are prepared from this mixture and stained according to Romanovsky-Giemsa. About 200 cells are examined under a microscope and the number of phagocytes that have absorbed the bacteria, the intensity of their capture and destruction are determined.1. The phagocytic index is the percentage of phagocytes that have absorbed bacteria after 30 and 120 minutes to the total number of cells examined.2. Phagocytic index - the average number of bacteria present in a phagocyte after 30 and 120 minutes (mathematically divide the total number of bacteria absorbed by phagocytes by the phagocytic index)

3. Phagocytosis completion index - calculated by dividing the number of killed bacteria in phagocytes by the total number of absorbed bacteria and multiplying by 100.

Information regarding the reference values ​​of indicators, as well as the composition of the indicators included in the analysis, may differ slightly depending on the laboratory!

Normal indicators of phagocytic activity: 1. Phagocytic index: after 30 minutes - 94.2±1.5, after 120 minutes - 92.0±2.52. Phagocytic indicator: after 30 minutes - 11.3±1.0, after 120 minutes - 9.8±1.0

1. Severe, long-term infections2. Manifestations of any immunodeficiency

3. Somatic diseases - liver cirrhosis, glomerulonephritis - with manifestations of immunodeficiency

1. In bacterial inflammatory processes (norm)2. Increased content of leukocytes in the blood (leukocytosis)3. Allergic reactions, autoallergic diseases A decrease in phagocytosis activity indicators indicates various disorders in the system of nonspecific cellular immunity. This may be due to reduced production of phagocytes, their rapid decay, impaired mobility, disruption of the process of absorption of foreign material, disruption of the processes of its destruction, etc. All this indicates a decrease in the body’s resistance to infection. Most often, phagocytic activity decreases when: 1. Against the background of severe infections, intoxications, ionizing radiation (secondary immunodeficiency)2. Systemic autoimmune connective tissue diseases (systemic lupus erythematosus, rheumatoid arthritis)3. Primary immunodeficiencies (Chediac-Higashi syndrome, chronic granulomatous disease)4. Chronic active hepatitis, liver cirrhosis

5. Some forms of glomerulonephritis

Phagocytosis

Phagocytosis is the absorption by a cell of large particles visible under a microscope (for example, microorganisms, large viruses, damaged cell bodies, etc.). The process of phagocytosis can be divided into two phases. In the first phase, particles bind to the surface of the membrane. In the second phase, the actual absorption of the particle and its further destruction occur. There are two main groups of phagocyte cells - mononuclear and polynuclear. Polynuclear neutrophils make up

the first line of defense against the penetration of various bacteria, fungi and protozoa into the body. They destroy damaged and dead cells, participate in the process of removing old red blood cells and cleaning the wound surface.

The study of phagocytosis indicators is important in the complex analysis and diagnosis of immunodeficiency conditions: often recurrent purulent-inflammatory processes, long-term non-healing wounds, and a tendency to postoperative complications. The study of the phagocytosis system helps in the diagnosis of secondary immunodeficiency conditions caused by drug therapy. The most informative for assessing the activity of phagocytosis is the phagocytic number, the number of active phagocytes and the phagocytosis completion index.

Phagocytic activity of neutrophils

Parameters characterizing the state of phagocytosis.

■ Phagocytic number: norm - 5-10 microbial particles. Phagocytic number is the average number of microbes absorbed by one blood neutrophil. Characterizes the absorption capacity of neutrophils.

■ Phagocytic capacity of blood: norm - 12.5-25x109 per 1 liter of blood. Phagocytic capacity of blood is the number of microbes that neutrophils can absorb in 1 liter of blood.

■ Phagocytic index: normal 65-95%. Phagocytic indicator - the relative number of neutrophils (expressed as a percentage) participating in phagocytosis.

■ Number of active phagocytes: norm - 1.6-5.0x109 in 1 liter of blood. The number of active phagocytes is the absolute number of phagocytic neutrophils in 1 liter of blood.

■ Phagocytosis completion index: the norm is more than 1. The phagocytosis completion index reflects the digestive ability of phagocytes.

The phagocytic activity of neutrophils usually increases at the beginning of the development of the inflammatory process. Its decrease leads to the chronicization of the inflammatory process and the maintenance of the autoimmune process, since this disrupts the function of destruction and removal of immune complexes from the body.

Diseases and conditions in which the phagocytic activity of neutrophils changes are presented in the table.

Table Diseases and conditions in which the phagocytic activity of neutrophils changes

Spontaneous test with NST

Normally, in adults, the number of NBT-positive neutrophils is up to 10%.

A spontaneous test with NBT (nitro blue tetrazolium) allows you to assess the state of the oxygen-dependent mechanism of bactericidal activity of blood phagocytes (granulocytes) in vitro. It characterizes the state and degree of activation of the intracellular NADP-H oxidase antibacterial system. The principle of the method is based on the reduction of the soluble dye NCT absorbed by the phagocyte into insoluble diformazan under the influence of superoxide anion (intended for intracellular destruction of the infectious agent after its absorption), formed in the NADPH-H oxidase reaction. Indicators of the NBT test increase in the initial period of acute bacterial infections, while during the subacute and chronic course of the infectious process they decrease. Sanitation of the body from the pathogen is accompanied by normalization of the indicator. A sharp decrease indicates decompensation of anti-infective defense and is considered a prognostically unfavorable sign.

The NBT test plays an important role in the diagnosis of chronic granulomatous diseases, which are characterized by the presence of defects in the NADP-H oxidase complex. Patients with chronic granulomatous diseases are characterized by the presence of recurrent infections (pneumonia, lymphadenitis, abscesses of the lungs, liver, skin) caused by Staphylococcus aureus, Klebsiella spp., Candida albicans, Salmonella spp., Escherichia coli, Aspergillus spp., Pseudomonas cepacia, Mycobacterium spp. and Pneumocystis carinii.

Neutrophils in patients with chronic granulomatous diseases have normal phagocytic function, but due to a defect in the NADPH oxidase complex they are not able to destroy microorganisms. Hereditary defects of the NADP-H oxidase complex in most cases are linked to chromosome X, less often they are autosomal recessive.

Spontaneous test with NST

A decrease in the spontaneous test with NBT is typical for chronic inflammatory process, congenital defects of the phagocytic system, secondary and primary immunodeficiencies, HIV infection, malignant neoplasms, severe burns, injuries, stress, malnutrition, treatment with cytostatics and immunosuppressants, exposure to ionizing radiation.

An increase in the spontaneous test with NBT is noted in case of antigenic irritation due to bacterial inflammation (prodromal period, period of acute manifestation of infection with normal phagocytosis activity), chronic granulomatosis, leukocytosis, increased antibody-dependent cytotoxicity of phagocytes, autoallergic diseases, allergies.

Activated test with NCT

Normally, in adults, the number of NBT-positive neutrophils is 40-80%.

The activated test with NBT allows one to assess the functional reserve of the oxygen-dependent mechanism of bactericidal phagocytes. The test is used to identify the reserve capabilities of intracellular phagocyte systems. With preserved intracellular antibacterial activity in phagocytes, a sharp increase in the number of formazan-positive neutrophils occurs after their stimulation with latex. A decrease in the activated NBT test of neutrophils below 40% and monocytes below 87% indicates a lack of phagocytosis.

Phagocytosis is an important link in protecting health. But it is known that it can occur with varying degrees of effectiveness. What does this depend on, and how can we determine the indicators of phagocytosis that reflect its “quality”?

Phagocytosis in various infections:

In fact, the first thing on which the strength of protection depends is the microbe itself, which “attacks” the body. Some microorganisms have special properties. Thanks to these properties, cells that participate in phagocytosis cannot destroy them.

For example, the pathogens of toxoplasmosis and tuberculosis are absorbed by phagocytes, but at the same time continue to develop inside them without any harm to themselves. This is achieved because they inhibit phagocytosis: the microbial membrane secretes substances that do not allow the phagocyte to act on them with the enzymes of its lysosomes.

Some streptococci, staphylococci, and gonococci can also live happily and even multiply inside phagocytes. These microbes produce compounds that neutralize the above enzymes.

Chlamydia and rickettsia not only settle inside the phagocyte, but also establish their own orders there. Thus, they dissolve the “bag” in which the phagocyte “catches” them, and pass into the cytoplasm of the cell. There they exist, using the resources of the phagocyte for their nutrition.

Finally, viruses are generally difficult to reach for phagocytosis: many of them immediately penetrate the cell nucleus, integrate into its genome and begin to control its work, invulnerable to immune defense and therefore very dangerous to health.

Thus, the possibility of ineffective phagocytosis can be judged by what exactly a person is sick with.

Tests that determine the quality of phagocytosis:

Phagocytosis involves mainly two types of cells: neutrophils and macrophages. Therefore, to find out how well phagocytosis proceeds in the human body, doctors study the indicators of mainly these cells. Below is a list of tests that allow you to find out how active polymicrobial phagocytosis is in a patient.

1. Complete blood count with determination of the number of neutrophils.

2. Determination of phagocytic number, or phagocytic activity. To do this, neutrophils are removed from a blood sample and observed as they carry out the process of phagocytosis. They are offered staphylococci, pieces of latex, and Candida fungi as “victims.” The number of phagocytosed neutrophils is divided by their total number, and the desired indicator of phagocytosis is obtained.

3. Calculation of the phagocytic index. As is known, each phagocyte can destroy several harmful objects throughout its life. When calculating the phagocytic index, laboratory assistants count how many bacteria were captured by one phagocyte. Based on the “gluttony” of phagocytes, a conclusion is drawn about how well the body’s defense is carried out.

4. Determination of the opsonophagocytic index. Opsonins are substances that enhance phagocytosis: the phagocyte membrane responds better to the presence of harmful particles in the body, and the process of their absorption is more active if there are a lot of opsonins in the blood. The opsonophagocytic index is determined by the ratio of the phagocytic index of the patient's serum and the same index of normal serum. The higher the index, the better the phagocytosis.

5. Determination of the speed of movement of phagocytes to harmful particles that have entered the body is carried out by a special reaction of inhibition of leukocyte migration.

There are other tests that can determine the capabilities of phagocytosis. We will not bore readers with details, we will only say that obtaining information about the quality of phagocytosis is possible, and for this you should contact an immunologist who will tell you what specific studies need to be done.

If there is reason to believe that you have a weak immune system, or if you know this for sure based on the results of the tests, you should start taking medications that will have a beneficial effect on the effectiveness of phagocytosis. The best of them today is the immunomodulator Transfer Factor. Its educational effect on the immune system, which is realized due to the presence of information molecules in the product, allows you to normalize all processes occurring in the immune system. Taking Transfer Factor is a necessary measure to improve the quality of all parts of the immune system, and therefore the key to maintaining and strengthening health in general.

Immunogram indicators - phagocytes, antistreptolysin O (ASLO)

Immunogram analysis is done to diagnose immunodeficiency.

The presence of immunodeficiency can be assumed if there is a significant decrease in immunogram parameters.

A slight fluctuation in the values ​​of indicators can be caused by various physiological reasons and is not a significant diagnostic sign.

Immunogram prices If you need more information, call!

Phagocytes

Phagocytes play a very important role in the natural or nonspecific immunity of the body.

The following types of leukocytes are capable of phagocytosis: monocytes, neutrophils, basophils and eosinophils. They can capture and digest large cells - bacteria, viruses, fungi, and remove their own dead tissue cells and old red blood cells. They can move from the blood to the tissues and perform their functions. During various inflammatory processes and allergic reactions, the number of these cells increases. To assess the activity of phagocytes, the following indicators are used:

• Phagocytic number - shows the number of particles that can absorb 1 phagocyte (normally a cell can absorb 5-10 microbial bodies),
• Phagocytic capacity of blood,
• Phagocytosis activity – reflects the percentage of phagocytes that can actively capture particles,
• Number of active phagocytes,
• Phagocytosis completion index (must be greater than 1).

To carry out such an analysis, special NST tests are used - spontaneous and stimulated.

The factors of natural immunity also include the complement system - these are complex active compounds called components, these include cytokines, interferons, interleukins.

Indicators of humoral immunity:

Phagocytosis activity (VF, %)

Intensity of phagocytosis (PF)

NST - spontaneous test, %

NST - stimulated test, %

A decrease in phagocyte activity may be a sign that phagocytes are not coping well with their function of neutralizing foreign particles.

Test for antistreptolysin O (ASLO)

With streptococcal infections caused by group A beta-hemolytic streptococcus, microbes that enter the body secrete a specific enzyme, streptolysin, which damages tissues and causes inflammation. In response, the body produces antistreptolysin O - these are antibodies to streptolysin. Antistreptolysin O - ASLO increases in the following diseases:

• Rheumatism,
• Rheumatoid arthritis,
• Glomerulonephritis,
• Tonsillitis,
• Pharyngitis,
• Chronic diseases of the tonsils,
• Scarlet fever,
• Erysipelas.

What organisms are capable of phagocytosis?

Answers and explanations

Platelets, or blood platelets, are mainly responsible for blood clotting, stopping bleeding, and forming blood clots. But, in addition to this, they also have phagocytic properties. Platelets can form pseudopods and destroy some harmful components that enter the body.

It turns out that the cellular lining of blood vessels also poses a danger to bacteria and other “invaders” that have entered the body. In the blood, monocytes and neutrophils fight foreign objects, in the tissues macrophages and other phagocytes wait for them, and even in the walls of blood vessels, being between the blood and tissues, “enemies” cannot “feel safe.” Truly, the body’s defense capabilities are extremely great. With an increase in the content of histamine in the blood and tissues, which occurs during inflammation, the phagocytic ability of endothelial cells, almost imperceptible before, increases several times!

Under this collective name all tissue cells are united: connective tissue, skin, subcutaneous tissue, organ parenchyma, and so on. No one could have imagined this before, but it turns out that under certain conditions, many histiocytes are able to change their “life priorities” and also acquire the ability to phagocytose! Damage, inflammation and other pathological processes awaken in them this ability, which is normally absent.

Phagocytosis and cytokines:

So, phagocytosis is a comprehensive process. Under normal conditions, it is carried out by phagocytes specially designed for this, but critical situations can force even those cells for which such a function is not in character. When the body is in real danger, there is simply no other way out. It’s like in war, when not only men take weapons in their hands, but also everyone who is able to hold it.

During the process of phagocytosis, cells produce cytokines. These are so-called signaling molecules, with the help of which phagocytes transmit information to other components of the immune system. The most important of the cytokines are transfer factors, or transfer factors - protein chains, which can be called the most valuable source of immune information in the body.

In order for phagocytosis and other processes in the immune system to proceed safely and fully, you can use the drug Transfer Factor, the active substance of which is represented by transfer factors. With each tablet of the product, the human body receives a portion of invaluable information about the proper functioning of the immune system, received and accumulated by many generations of living beings.

When taking Transfer Factor, the processes of phagocytosis are normalized, the response of the immune system to the penetration of pathogens is accelerated, and the activity of cells that protect us from aggressors increases. In addition, by normalizing the immune system, the functions of all organs are improved. This allows you to increase your overall level of health and, if necessary, help the body fight almost any disease.

Cells capable of phagocytosis include

Polymorphonuclear leukocytes (neutrophils, eosinophils, basophils)

Fixed macrophages (alveolar, peritoneal, Kupffer, dendritic cells, Langerhans

2. What type of immunity provides protection for mucous membranes communicating with the external environment. and skin from penetration of the pathogen into the body: specific local immunity

3. The central organs of the immune system include:

Bursa of Fabricius and its analogue in humans (Peyre's patches)

4. What cells produce antibodies:

B. Plasma cells

5. Haptens are:

Simple organic compounds with low molecular weight (peptides, disaccharides, NK, lipids, etc.)

Unable to induce antibody formation

Capable of specifically interacting with those antibodies in the induction of which they participated (after attaching to a protein and transforming into full-fledged antigens)

6. Penetration of the pathogen through the mucous membrane is prevented by class immunoglobulins:

7. The function of adhesins in bacteria is performed by: cell wall structures (fimbriae, outer membrane proteins, LPS)

U Gr(-): associated with pili, capsule, capsule-like membrane, outer membrane proteins

U Gr(+): teichoic and lipoteichoic acids of the cell wall

8. Delayed hypersensitivity is caused by:

Sensitized T-lymphocyte cells (lymphocytes that have undergone immunological “training” in the thymus)

9. Cells that carry out a specific immune response include:

10. Components required for the agglutination reaction:

microbial cells, latex particles (agglutinogens)

11. The components for staging the precipitation reaction are:

A. Cell suspension

B. Antigen solution (hapten in physiological solution)

B. Heated microbial cell culture

D. Immune serum or test serum of the patient

12. What components are necessary for the complement fixation reaction:

patient's blood serum

13 Components required for the immune lysis reaction:

D. Saline solution

14. In a healthy person, the number of T-lymphocytes in the peripheral blood is:

15. Drugs used for emergency prevention and treatment:

16. The method for quantitative assessment of human peripheral blood T-lymphocytes is the reaction:

B. Complement fixation

B. Spontaneous rosette formation with sheep erythrocytes (E-ROC)

G. Rosette formations with mouse erythrocytes

D. Rosette formations with erythrocytes treated with antibodies and complement (EAS-ROK )

17. When mouse erythrocytes are mixed with human peripheral blood lymphocytes, “E-rosettes” are formed with those cells that are:

B. Undifferentiated lymphocytes

18. To perform the latex agglutination reaction, you must use all of the following ingredients, except:

A. Patient’s blood serum diluted 1:25

B. Phosphate-buffered saline (saline)

D. Antigenic latex diagnosticum

19. What type of reactions does the test using latex diagnosticum include:

20. How does a positive latex agglutination reaction manifest itself when placed in plates for immunological reactions:

A. Formation of flocs

B. Antigen dissolution

B. Turbidity of the medium

D. Formation of a thin film at the bottom of the plate well with an uneven edge (“umbrella” shape)

D. Rim in the center at the bottom of the hole in the form of a “button”

21.For what purpose is the Mancini immunodiffusion reaction used:

A. Detection of whole bacterial cells

B. Determination of polysaccharide – bacterial antigen

B. Quantitative determination of immunoglobulin classes

D. Determination of the activity of phagocytic cells

22. To determine the amount of immunoglobulins in blood serum, use the following test:

B. enzymatic immunity

B. radioimmune test

G. radial immunodiffusion according to Mancini

23. What are the names of the antibodies involved in the Mancini immunodiffusion reaction:

A. Antibacterial antibodies

B. Antivirus AT

B. Complement-fixing antibodies

D. Anti-immunoglobulin antibodies

24. What form of infection are diseases associated with the entry of a pathogen from the environment:

A. a disease caused by a single pathogen

B. a disease that develops due to infection with several types of pathogens

B. a disease that developed against the background of another disease

A. blood is a mechanical carrier of the microbe, but it does not multiply in the blood

B. the pathogen multiplies in the blood

B. the pathogen enters the blood from purulent foci

27. After recovery from typhoid fever, the pathogen is released from the body for a long time. What form of infection are these cases:

A. Chronic infection

B. Latent infection

B. Asymptomatic infection

28. The main properties of bacterial exotoxins are:

A. Firmly associated with the body of bacteria

D. Easily released into the environment

H. Under the influence of formalin they can turn into toxoid

I. Cause the formation of antitoxins

K. Antitoxins are not formed

29. The invasive properties of pathogenic bacteria are due to:

A. the ability to secrete saccharolytic enzymes

B. the presence of the enzyme hyalorunidase

B. release of distribution factors (fibrinolysin, etc.)

D. loss of cell wall

D. ability to form capsules

H. presence of the col gene

30. According to the biochemical structure, antibodies are:

31. If an infectious disease is transmitted to a person from a sick animal, it is called:

32. Basic properties and signs of a full-fledged antigen:

A. is a protein

B. is a low molecular weight polysaccharide

G. is a high molecular weight compound

D. causes the formation of antibodies in the body

E. does not cause the formation of antibodies in the body

Z. insoluble in body fluids

I. is able to react with a specific antibody

K. is not able to react with a specific antibody

33. Nonspecific resistance of a macroorganism includes all of the following factors, except:

B. gastric juice

E. temperature reaction

G. mucous membranes

Z. lymph nodes

K. complement system

34. After the vaccine is administered, the following type of immunity is developed:

G. acquired artificial active

35. Which of the following agglutination reactions are used to identify the type of microorganism:

B. extensive Gruber agglutination reaction

B. indicative agglutination reaction on glass

G. latex agglutination reaction

D. passive hemagglutination reaction with O-diagnosticum erythrocytes

36. Which of the following reactions is used to obtain adsorbed and monoreceptor agglutinating sera:

A. indicative agglutination reaction on glass

B. indirect hemagglutination reaction

B. extensive Gruber agglutination reaction

D. adsorption reaction of agglutinins according to Castellani

D. precipitation reaction

E. expanded Widal agglutination reaction

37. The necessary ingredients for staging any agglutination reaction are:

A. distilled water

B. saline solution

G. antigen (suspension of microbes)

E. red blood cell suspension

H. suspension of phagocytes

38.For what purpose are precipitation reactions used:

A. detection of agglutinins in the patient’s blood serum

B. detection of microorganism toxins

B. detection of blood type

D. detection of precipitins in blood serum

D. retrospective diagnosis of the disease

E. definition of food adulteration

G. determination of toxin strength

H. quantitative determination of classes of serum immunoglobulins

39. The necessary ingredients for staging an indirect hemagglutination reaction are:

A. distilled water

B. patient’s blood serum

B. saline solution

G. erythrocyte diagnosticum

D. monoreceptor agglutinating serum

E. unadsorbed agglutinating serum

H. red blood cell suspension

40. The main properties and characteristics of precipitinogen-hapten are:

A. is a whole microbial cell

B. is an extract from a microbial cell

V. is a toxin of microorganisms

D. is an inferior antigen

E. soluble in saline solution

G. causes the production of antibodies when introduced into the macroorganism

I. reacts with the antibody

41. Time to take into account the ring precipitation reaction:

42. Which of the following immune reactions is used to determine the toxigenicity of a microorganism culture:

A. Widal agglutination reaction

B. ring precipitation reaction

B. Gruber agglutination reaction

D. phagocytosis reaction

E. gel precipitation reaction

G. neutralization reaction

H. lysis reaction

I. hemagglutination reaction

K. flocculation reaction

43. The necessary ingredients for staging the hemolysis reaction are:

A. hemolytic serum

B. pure culture of bacteria

B. antibacterial immune serum

D. saline solution

G. bacterial toxins

44.For what purpose are bacteriolysis reactions used:

A. detection of antibodies in the patient’s blood serum

B. detection of microorganism toxins

B. identification of pure culture of microorganisms

D. determination of toxoid strength

45.For what purpose is RSK used:

A. determination of antibodies in the patient’s blood serum

B. identification of a pure culture of a microorganism

46. ​​Signs of a positive bacteriolysis reaction are:

E. dissolution of bacteria

47. Signs of positive RSC are:

A. turbidity of the liquid in a test tube

B. immobilization of bacteria (loss of mobility)

B. formation of varnish blood

D. appearance of a cloudy ring

D. the liquid in the test tube is transparent, there is a sediment of red blood cells at the bottom

E. the liquid is transparent, there are bacterial flakes at the bottom

48. For active immunization the following are used:

B. immune serum

49. What bacteriological preparations are prepared from bacterial toxins:

50. What ingredients are needed to prepare a killed vaccine:

Highly virulent and highly immunogenic strain of microorganism (whole killed bacterial cells)

Heating at t=56-58C for 1 hour

Exposure to ultraviolet rays

51. Which of the following bacterial preparations are used to treat infectious diseases:

A. live vaccine

G. antitoxic serum

H. agglutinating serum

K. precipitating serum

52. For what immune reactions are diagnosticums used:

Expanded agglutination reaction of the Vidal type

Passive or indirect hemagglutination reactions (IRHA)

53. Duration of the protective effect of immune sera introduced into the human body: 2-4 weeks

54. Methods of introducing the vaccine into the body:

through the mucous membranes of the respiratory tract using artificial aerosols of live or killed vaccines

55. Main properties of bacterial endotoxins:

A. are proteins(cell wall of Gr(-) bacteria)

B. consist of lipopolysaccharide complexes

G. are easily released from bacteria into the environment

I. are capable of turning into toxoid under the influence of formalin and temperature

K. causes the formation of antitoxins

56. The occurrence of an infectious disease depends on:

A. forms of bacteria

B. reactivity of the microorganism

B. Gram staining ability

D. degree of pathogenicity of the bacterium

E. portal of entry infection

G. state of the cardiovascular system of the microorganism

Z. environmental conditions (atmospheric pressure, humidity, solar radiation, temperature, etc.)

57. MHC (major histocompatibility complex) antigens are located on the membranes:

A. nucleated cells of different microorganism tissues (leukocytes, macrophages, histiocytes, etc.)

B. only leukocytes

58. The ability of bacteria to secrete exotoxins is due to:

A. form of bacteria

B. ability to form capsules

59. The main properties of pathogenic bacteria are:

A. the ability to cause an infectious process

B. ability to form spores

B. specificity of action on the macroorganism

E. ability to form toxins

H. ability to form sugars

I. ability to form capsules

60. Methods for assessing a person’s immune status are:

A. agglutination reaction

B. ring precipitation reaction

G. radial immunodiffusion according to Mancini

D. immunofluorescence test with monoclonal antibodies to identify T-helper and T-suppressor cells

E. complement fixation reaction

G. method of spontaneous rosette formation with sheep erythrocytes (E-ROK)

61. Immunological tolerance is:

A. ability to produce antibodies

B. the ability to cause proliferation of a specific cell clone

B. lack of immunological response to antigen

62. Inactivated blood serum:

Serum subjected to heat treatment at 56C for 30 minutes, which led to the destruction of complement

63. Cells that suppress the immune response and participate in the phenomenon of immunotolerance are:

B. lymphocytes T-suppressors

D. lymphocytes T-effectors

D. lymphocytes T killers

64. The functions of T-helper cells are:

Necessary for the transformation of B lymphocytes into antibody-forming cells and memory cells

Recognize cells that have MHC class 2 antigens (macrophages, B lymphocytes)

Regulates the immune response

65. Mechanism of precipitation reaction:

A. formation of an immune complex on cells

B. toxin inactivation

B. formation of a visible complex when an antigen solution is added to serum

D. Glow of the antigen-antibody complex in ultraviolet rays

66. The division of lymphocytes into T and B populations is due to:

A. the presence of certain receptors on the surface of cells

B. site of proliferation and differentiation of lymphocytes (bone marrow, thymus)

B. the ability to produce immunoglobulins

D. presence of the HGA complex

D. the ability to phagocytose antigen

67. Aggression enzymes include:

Protease (destroys antibodies)

Coagulase (clotts blood plasma)

Hemolysin (destroys the membranes of red blood cells)

Fibrinolysin (dissolution of fibrin clot)

Lecithinase (acts on lecithin)

68. Class immunoglobulins pass through the placenta:

69.Protection against diphtheria, botulism, and tetanus is determined by immunity:

70. The reaction of indirect hemagglutination involves:

A. erythrocyte antigens participate in the reaction

B. the reaction involves antigens sorbed on erythrocytes

B. the reaction involves receptors for adhesins of the pathogen

A. blood is a mechanical carrier of the pathogen

B. the pathogen multiplies in the blood

B. the pathogen enters the blood from purulent foci

72. Intradermal test to detect antitoxic immunity:

The Schick test with diphtheria toxin is positive if there are no antibodies in the body that can neutralize the toxin

73. Mancini’s immunodiffusion reaction refers to a type reaction:

A. agglutination reaction

B. lysis reaction

B. precipitation reaction

D. ELISA (enzyme-linked immunosorbent assay)

E. phagocytosis reaction

G. RIF (immunofluorescence reaction)

74. Reinfection is:

A. a disease that develops after recovery from repeated infection with the same pathogen

B. a disease that developed during infection with the same pathogen before recovery

B. return of clinical manifestations

75. The visible result of a positive Mancini reaction is:

A. formation of agglutinins

B. turbidity of the medium

B. cell dissolution

D. formation of precipitation rings in the gel

76. Human resistance to the causative agent of chicken cholera determines immunity:

77. Immunity is maintained only in the presence of a pathogen:

78. The latex agglutination reaction cannot be used for the following purposes:

A. identification of the pathogen

B. determination of immunoglobulin classes

B. detection of antibodies

79. Rosette formation reaction with sheep erythrocytes (E-ROC) is considered

positive if one lymphocyte adsorbs:

A. one sheep red blood cell

B. complement fraction

B. more than 2 sheep red blood cells (more than 10)

G. bacterial antigen

80. Incomplete phagocytosis is observed in diseases:

K. anthrax

81. Specific and nonspecific factors of humoral immunity are:

82. When sheep erythrocytes are mixed with human peripheral blood lymphocytes, E-rosettes are formed only with those cells that are:

83. The results of the latex agglutination reaction are recorded in:

A. in milliliters

B. in millimeters

84. Precipitation reactions include:

B. flocculation reaction (according to Korotyaev)

B. phenomenon of Isaev Pfeiffer

G. precipitation reaction in gel

D. agglutination reaction

E. bacteriolysis reaction

G. hemolysis reaction

H. Ascoli ring-reception reaction

I. Mantoux reaction

K. radial immunodiffusion reaction according to Mancini

85. Main features and properties of hapten:

A. is a protein

B. is a polysaccharide

G. has a colloidal structure

D. is a high molecular weight compound

E. when introduced into the body, it causes the formation of antibodies

G. when introduced into the body does not cause the formation of antibodies

Z. soluble in body fluids

I. is able to react with specific antibodies

K. is not able to react with specific antibodies

86. Main features and properties of antibodies:

A. are polysaccharides

B. are albumins

V. are immunoglobulins

G. are formed in response to the introduction of a full-fledged antigen into the body

D. are formed in the body in response to the introduction of hapten

E. are capable of interacting with a full-fledged antigen

G. are capable of interacting with hapten

87. Necessary components for staging a detailed Gruber-type agglutination reaction:

A. patient’s blood serum

B. saline solution

B. pure culture of bacteria

D. known immune serum, non-adsorbed

D. red blood cell suspension

H. known immune serum, adsorbed

I. monoreceptor serum

88. Signs of a positive Gruber reaction:

89. Necessary ingredients for performing a detailed Widal agglutination reaction:

Diagnosticum (suspension of killed bacteria)

Patient's blood serum

90. Antibodies that enhance phagocytosis:

D. complement-fixing antibodies

91. Components of the ring precipitation reaction:

A. saline solution

B. precipitating serum

B. suspension of red blood cells

D. pure culture of bacteria

H. bacterial toxins

92. To detect agglutinins in the patient’s blood serum, the following are used:

A. extensive Gruber agglutination reaction

B. bacteriolysis reaction

B. extended Vidal agglutination reaction

D. precipitation reaction

D. passive hemagglutination reaction with erythrocyte diagonisticum

E. indicative agglutination reaction on glass

93. Lysis reactions are:

A. precipitation reaction

B. Isaev-Pfeiffer phenomenon

B. Mantoux reaction

G. Gruber agglutination reaction

E. Widal agglutination reaction

94. Signs of a positive ring precipitation reaction:

A. turbidity of the liquid in a test tube

B. loss of bacterial motility

B. appearance of sediment at the bottom of the test tube

D. appearance of a cloudy ring

D. formation of varnish blood

E. the appearance of white lines of turbidity in the agar ("uson")

95. Time for final accounting of the Grubber agglutination reaction:

96. To set up the bacteriolysis reaction it is necessary:

B. distilled water

D. saline solution

D. red blood cell suspension

E. pure culture of bacteria

G. suspension of phagocytes

I. bacterial toxins

K. monoreceptor agglutinating serum

97. For the prevention of infectious diseases the following are used:

E. antitoxic serum

K. agglutinating serum

98. After an illness, the following type of immunity is developed:

B. acquired natural active

B. acquired artificial active

G. acquired natural passive

D. acquired artificial passive

99. After the administration of immune serum, the following type of immunity is formed:

B. acquired natural active

B. acquired natural passive

G. acquired artificial active

D. acquired artificial passive

100. Time for final recording of the results of the lysis reaction performed in a test tube:

101.Number of phases of the complement fixation reaction (CRR):

D. more than ten

102. Signs of a positive hemolysis reaction:

A. precipitation of red blood cells

B. formation of varnish blood

B. agglutination of red blood cells

D. appearance of a cloudy ring

D. turbidity of the liquid in a test tube

103. For passive immunization the following are used:

B. antitoxic serum

104. The ingredients necessary for staging the RSC are:

A. distilled water

B. saline solution

D. patient's blood serum

E. bacterial toxins

I. hemolytic serum

105. For the diagnosis of infectious diseases the following are used:

B. antitoxic serum

G. agglutinating serum

I. precipitating serum

106. Bacteriological preparations are prepared from microbial cells and their toxins:

B. antitoxic immune serum

B. antimicrobial immune serum

107. Antitoxic serums are the following:

D. against gas gangrene

K. against tick-borne encephalitis

108. Select the correct sequence of the listed stages of bacterial phagocytosis:

1A. approach of the phagocyte to the bacterium

2B. adsorption of bacteria on phagocyte

3B. engulfment of bacteria by phagocyte

4G. phagosome formation

5D. fusion of phagosome with mesosome and formation of phagolysosome

6E. intracellular inactivation of a microbe

7J. enzymatic digestion of bacteria and removal of remaining elements

109. Select the correct sequence of stages of interaction (intercellular cooperation) in the humoral immune response in the case of the introduction of a thymus-independent antigen:

4A. Formation of clones of plasma cells producing antibodies

1B. Capture, intracellular gene disintegration

3B. Antigen recognition by B lymphocytes

2G. Presentation of disintegrated antigen on the macrophage surface

110. An antigen is a substance with the following properties:

Immunogenicity (tolerogenicity), determined by foreignness

111. Number of immunoglobulin classes in humans: five

112. IgG in the blood serum of a healthy adult makes up the total content of immunoglobulins: 75-80%

113. During electrophoresis of human blood serum, Ig migrates to the zone of: γ-globulins

114. In immediate allergic reactions, the following is of greatest importance:

Production of antibodies of different classes

115. The receptor for sheep erythrocytes is present on the membrane of: T-lymphocyte

116. B-lymphocytes form rosettes with:

mouse erythrocytes treated with antibodies and complement

117. What factors should be taken into account when assessing immune status:

The frequency of infectious diseases and the nature of their course

Severity of temperature reaction

Presence of foci of chronic infection

118. “Zero” lymphocytes and their number in the human body are:

lymphocytes that have not undergone differentiation, which are precursor cells, their number is 10-20%

119. Immunity is:

A system of biological protection of the internal environment of a multicellular organism (maintaining homeostasis) from genetically foreign substances of exogenous and endogenous nature

120. Antigens are:

Any substances contained in microorganisms and other cells or secreted by them, which carry signs of foreign information and, when introduced into the body, cause the development of specific immune reactions (all known antigens are of colloidal nature) + proteins. polysaccharides, phospholipids. nucleic acids

121. Immunogenicity is:

Ability to induce an immune response

122. Haptens are:

Simple chemical compounds of low molecular weight (disaccharides, lipids, peptides, nucleic acids)

Not immunogenic

Have a high level of specificity for immune response products

123. The main class of human immunoglobulins that are cytophilic and provide an immediate hypersensitivity reaction is: IgE

124. During the primary immune response, the synthesis of antibodies begins with a class of immunoglobulins:

125. During a secondary immune response, antibody synthesis begins with a class of immunoglobulins:

126. The main cells of the human body that provide the pathochemical phase of the immediate hypersensitivity reaction, releasing histamine and other mediators, are:

Basophils and mast cells

127. Delayed hypersensitivity reactions involve:

T helper cells, T suppressor cells, macrophages and memory cells

128. The maturation and accumulation of which mammalian peripheral blood cells never occurs in the bone marrow:

129. Find correspondence between the type of hypersensitivity and the mechanism of implementation:

1.Anaphylactic reaction– production of IgE antibodies upon initial contact with an allergen, antibodies are fixed on the surface of basophils and mast cells, upon repeated exposure to the allergen, mediators are released - histamine, seratonin, etc.

2. Cytotoxic reactions– IgG, IgM, IgA antibodies are involved, fixed on various cells, the AG-AT complex activates the complement system along the classical pathway, trace. cell cytolysis.

3.Immunocomplex reactions– formation of IC (soluble antigen associated with antibody + complement), complexes are fixed on immunocompetent cells and deposited in tissues.

4. Cell-mediated reactions– the antigen interacts with pre-sensitized immunocompetent cells, these cells begin to produce mediators, causing inflammation (DTH)

130. Find correspondence between the pathway of complement activation and the mechanism of implementation:

1. Alternative path– due to polysaccharides, lipopolysaccharides of bacteria, viruses (AG without the participation of antibodies), the C3b component binds, with the help of the properdin protein this complex activates the C5 component, then the formation of MAC => lysis of microbial cells

2.Classic way– due to the Ag-At complex (complexes of IgM, IgG with antigens, binding of component C1, cleavage of components C2 and C4, formation of C3 convertase, formation of component C5

3.Lectin pathway– due to mannan-binding lectin (MBL), activation of protease, cleavage of components C2-C4, classic version. Paths

131. Antigen processing is:

The phenomenon of recognition of a foreign antigen by the capture, cleavage and binding of antigen peptides with molecules of the major histocompatibility complex class 2 and their presentation on the cell surface

132. Find correspondence between the properties of the antigen and the development of the immune response:

133. Find correspondence between the type of lymphocytes, their quantity, properties and the way of their differentiation:

1. T-helpers, C D 4-lymphocytes – APC is activated, together with the MHC class 2 molecule, division of the population into Th1 and Th2 (differing in interleukins), form memory cells, and Th1 can turn into cytotoxic cells, differentiation in the thymus, 45-55%

2.C D 8 - lymphocytes - cytotoxic effect, activated by class 1 MHC molecule, can play the role of suppressor cells, form memory cells, destroy target cells (“lethal blow”), 22-24%

3.B lymphocyte - differentiation in the bone marrow, the receptor receives only one receptor, can, after interaction with the antigen, go into the T-dependent pathway (due to IL-2 T-helper, the formation of memory cells and other classes of immunoglobulins) or T-independent (only IgM are formed) .10-15%

134. The main role of cytokines:

Regulator of intercellular interactions (mediator)

135. Cells involved in presenting antigen to T lymphocytes are:

136. To produce antibodies, B lymphocytes receive help from:

137. T lymphocytes recognize antigens that are presented in association with molecules:

Major histocompatibility complex on the surface of antigen presenting cells)

138. Antibodies of the IgE class are produced: during allergic reactions, by plasma cells in the bronchial and peritoneal lymph nodes, in the mucous membrane of the gastrointestinal tract

139. The phagocytic reaction is performed:

140. Neutrophil leukocytes have the following functions:

Capable of phagocytosis

Secrete a wide range of biologically active substances (IL-8 causes degranulation)

Associated with the regulation of tissue metabolism and the cascade of inflammatory reactions

141. The following occurs in the thymus: maturation and differentiation of T-lymphocytes

142. The major histocompatibility complex (MHC) is responsible for:

A. are markers of the individuality of their body

B. are formed when the cells of the body are damaged by any agents (infectious) and mark cells that must be destroyed by T-killers

V. participate in immunoregulation, represent antigenic determinants on the membrane of macrophages and interact with T helper cells

143. Antibody formation occurs in: plasma cells

Pass through the placenta

Opsonization of corpuscular antigens

Complement binding and activation via the classical pathway

Bacteriolysis and neutralization of toxigens

Agglutination and precipitation of antigens

145. Primary immunodeficiencies develop as a result of:

Defects in genes (such as mutations) that control the immune system

146. Cytokines include:

interleukins (1,2,3,4, etc.)

tumor necrosis factors

147. Find correspondence between various cytokines and their main properties:

1. Hematopoietins- cell growth factors (ID provides growth stimulation, differentiation and activation of T-.B-lymphocytes,N.K.-cells, etc.) and colony-stimulating factors

2.Interferons– antiviral activity

3.Tumor necrosis factors– lyses some tumors, stimulates antibody formation and mononuclear cell activity

4.Chemokines -attract leukocytes, monocytes, lymphocytes to the site of inflammation

148. Cells that synthesize cytokines are:

thymic stromal cells

149. Allergens are:

1.full antigens of protein nature:

food products (eggs, milk, nuts, shellfish); poisons of bees, wasps; hormones; animal serum; enzyme preparations (streptokinase, etc.); latex; components of house dust (mites, mushrooms, etc.); pollen of grasses and trees; vaccine components

150. Find correspondence between the level of tests characterizing a person’s immune status and the main indicators of the immune system:

1st level- screening (leukocyte formula, determination of phagocytosis activity by the intensity of chemotaxis, determination of immunoglobulin classes, counting the number of B-lymphocytes in the blood, determination of the total number of lymphocytes and the percentage of mature T-lymphocytes)

2nd level – quantities. determination of T-helpers/inducers and T-killers/suppressors, determination of the expression of adhesion molecules on the surface membrane of neutrophils, assessment of the proliferative activity of lymphocytes for the main mitogens, determination of proteins of the complement system, determination of acute phase proteins, subclasses of immunoglobulins, determination of the presence of autoantibodies, performing skin tests

151. Find correspondence between the form of the infectious process and its characteristics:

By origin: exogenous– the pathogenic agent comes from outside

endogenous– the cause of infection is a representative of the opportunistic microflora of the macroorganism itself

autoinfection– when pathogens are introduced from one biotope of a macroorganism to another

By duration: acute, subacute and chronic (the pathogen persists for a long time)

By distribution: focal (localized) and generalized (spread through the lymphatic tract or hematogenously): bacteremia, sepsis and septicopyemia

According to the site of infection: community-acquired, hospital-acquired, natural-focal

152. Select the correct sequence of periods in the development of an infectious disease:

3.period of pronounced clinical symptoms (acute period)

4. period of convalescence (recovery) - possible bacterial carriage

153. Find correspondences between the type of bacterial toxin and their properties:

1.cytotoxins– block protein synthesis at the subcellular level

2. membrane toxins– increase surface permeability. membranes of erythrocytes and leukocytes

3.functional blockers- distortion of nerve impulse transmission, increased vascular permeability

4.exfoliatins and erythrogenins

154. Allergens contain:

155. Incubation period is: the time from the moment a microbe enters the body until the first signs of disease appear, which is associated with reproduction, accumulation of microbes and toxin

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The protective role of mobile blood cells and tissues was first discovered by I. I. Mechnikov in 1883. He called these cells phagocytes and formulated the basic principles of the phagocytic theory of immunity. Phagocytosis- absorption of large macromolecular complexes or corpuscles and bacteria by the phagocyte. Phagocyte cells: neutrophils and monocytes/macrophages. Eosinophils can also phagocytose (they are most effective in anthelmintic immunity). The process of phagocytosis is enhanced by opsonins that envelop the object of phagocytosis. Monocytes make up 5-10%, and neutrophils 60-70% of blood leukocytes. Entering the tissue, monocytes form a population of tissue macrophages: Kupffer cells (or stellate reticuloendotheliocytes of the liver), microglia of the central nervous system, osteoclasts of bone tissue, alveolar and interstitial macrophages).

Process of phagocytosis. Phagocytes move directionally to the object of phagocytosis, reacting to chemoattractants: microbial substances, activated complement components (C5a, C3a) and cytokines.
The phagocyte plasmalemma envelops bacteria or other corpuscles and its own damaged cells. Then the object of phagocytosis is surrounded by the plasmalemma and the membrane vesicle (phagosome) is immersed in the cytoplasm of the phagocyte. The phagosome membrane merges with the lysosome and the phagocytosed microbe is destroyed, the pH acidifies to 4.5; Lysosome enzymes are activated. The phagocytosed microbe is destroyed under the action of lysosome enzymes, cationic defensin proteins, cathepsin G, lysozyme and other factors. During an oxidative (respiratory) explosion, toxic antimicrobial forms of oxygen are formed in the phagocyte - hydrogen peroxide H 2 O 2, superoxidation O 2 -, hydroxyl radical OH -, singlet oxygen. In addition, nitric oxide and the NO - radical have an antimicrobial effect.
Macrophages perform a protective function even before interacting with other immunocompetent cells (nonspecific resistance). Macrophage activation occurs after the destruction of the phagocytosed microbe, its processing (processing) and presentation (presentation) of the antigen to T-lymphocytes. In the final stage of the immune response, T lymphocytes release cytokines that activate macrophages (acquired immunity). Activated macrophages, together with antibodies and activated complement (C3b), carry out more effective phagocytosis (immune phagocytosis), destroying phagocytosed microbes.

Phagocytosis can be complete, ending with the death of the captured microbe, or incomplete, in which the microbes do not die. An example of incomplete phagocytosis is the phagocytosis of gonococci, tubercle bacilli and Leishmania.

All phagocytic cells of the body, according to I. I. Mechnikov, are divided into macrophages and microphages. Microphages include polymorphonuclear blood granulocytes: neutrophils, eosinophils and basophils. Macrophages of various tissues of the body (connective tissue, liver, lungs, etc.), together with blood monocytes and their bone marrow precursors (promonocytes and monoblasts), are combined into a special system of mononuclear phagocytes (MPF). The SMF is phylogenetically more ancient than the immune system. It is formed quite early in ontogenesis and has certain age-related characteristics.

Microphages and macrophages have a common myeloid origin - from a pluripotent stem cell, which is a single precursor of granulo- and monocytopoiesis. Peripheral blood contains more granulocytes (60 to 70% of all blood leukocytes) than monocytes (1 to 6%). At the same time, the duration of circulation of monocytes in the blood is much longer (half-life 22 hours) than that of short-lived granulocytes (half-life 6.5 hours). Unlike blood granulocytes, which are mature cells, monocytes, leaving the bloodstream, mature into tissue macrophages in the appropriate microenvironment. The extravascular pool of mononuclear phagocytes is tens of times greater than their number in the blood. The liver, spleen, and lungs are especially rich in them.

All phagocytic cells are characterized by common basic functions, similarity of structures and metabolic processes. The outer plasma membrane of all phagocytes is an actively functioning structure. It is characterized by pronounced folding and carries many specific receptors and antigenic markers, which are constantly updated. Phagocytes are equipped with a highly developed lysosomal apparatus, which contains a rich arsenal of enzymes. The active participation of lysosomes in the functions of phagocytes is ensured by the ability of their membranes to merge with the membranes of phagosomes or with the outer membrane. In the latter case, cell degranulation occurs and concomitant secretion of lysosomal enzymes into the extracellular space.

Phagocytes have three functions:

1 - protective, associated with cleansing the body of infectious agents, tissue decay products, etc.;

2 - presenting, consisting in the presentation of antigenic epitopes on the phagocyte membrane;

3 - secretory, associated with the secretion of lysosomal enzymes and other biologically active substances - monokines, which play an important role in immunogenesis.

Fig 1. Functions of a macrophage.

In accordance with the listed functions, the following sequential stages of phagocytosis are distinguished.

1. Chemotaxis - targeted movement of phagocytes in the direction of a chemical gradient of chemoattractants in the environment. The ability for chemotaxis is associated with the presence on the membrane of specific receptors for chemoattractants, which can be bacterial components, degradation products of body tissues, activated fractions of the complement system - C5a, C3a, lymphocyte products - lymphokines.

2. Adhesion (attachment) is also mediated by the corresponding receptors, but can proceed in accordance with the laws of nonspecific physicochemical interaction. Adhesion immediately precedes endocytosis (uptake).

3. Endocytosis is the main physiological function of the so-called professional phagocytes. There are phagocytosis - in relation to particles with a diameter of at least 0.1 microns and pinocytosis - in relation to smaller particles and molecules. Phagocytic cells are capable of capturing inert particles of coal, carmine, latex, flowing around them with pseudopodia without the participation of specific receptors. At the same time, phagocytosis of many bacteria, yeast-like fungi of the genus Candida and other microorganisms is mediated by special mannose fucose receptors of phagocytes, which recognize the carbohydrate components of the surface structures of microorganisms. The most effective is receptor-mediated phagocytosis for the Fc fragment of immunoglobulins and for the C3 fraction of complement. This phagocytosis is called immune, since it occurs with the participation of specific antibodies and the activated complement system, which opsonize the microorganism. This makes the cell highly susceptible to engulfment by phagocytes and leads to subsequent intracellular death and degradation. As a result of endocytosis, a phagocytic vacuole is formed - a phagosome. It should be emphasized that the endocytosis of microorganisms largely depends on their pathogenicity. Only avirulent or low-virulent bacteria (non-capsular strains of pneumococcus, strains of streptococcus lacking hyaluronic acid and M-protein) are directly phagocytosed. Most bacteria endowed with aggressive factors (staphylococci - A-protein, E. coli - expressed capsular antigen, salmonella - Vi-antigen, etc.) are phagocytosed only after they are opsonized by complement and/or antibodies.

The presentation, or representing, function of macrophages is to fix antigenic epitopes of microorganisms on the outer membrane. In this form, they are presented by macrophages for their specific recognition by cells of the immune system - T-lymphocytes.

The secretory function consists of the secretion of biologically active substances - monokines - by mononuclear phagocytes. These include substances that have a regulating effect on the proliferation, differentiation and functions of phagocytes, lymphocytes, fibroblasts and other cells. A special place among them is occupied by interleukin-1 (IL-1), which is secreted by macrophages. It activates many functions of T lymphocytes, including the production of the lymphokine interleukin-2 (IL-2). IL-1 and IL-2 are cellular mediators involved in the regulation of immunogenesis and various forms of immune response. At the same time, IL-1 has the properties of an endogenous pyrogen, since it induces fever by acting on the nuclei of the anterior hypothalamus. Macrophages produce and secrete such important regulatory factors as prostaglandins, leukotrienes, cyclic nucleotides with a wide spectrum of biological activity.

Along with this, phagocytes synthesize and secrete a number of products with predominantly effector activity: antibacterial, antiviral and cytotoxic. These include oxygen radicals (O 2, H 2 O 2), complement components, lysozyme and other lysosomal enzymes, interferon. Due to these factors, phagocytes can kill bacteria not only in phagolysosomes, but also outside cells, in the immediate microenvironment. These secretory products can also mediate the cytotoxic effect of phagocytes on various target cells in cell-mediated immune reactions, for example, in a delayed-type hypersensitivity reaction (DTH), in homograft rejection, and in antitumor immunity.

The considered functions of phagocytic cells ensure their active participation in maintaining homeostasis of the body, in the processes of inflammation and regeneration, in nonspecific anti-infective defense, as well as in immunogenesis and specific cellular immunity reactions (SCT). The early involvement of phagocytic cells (first granulocytes, then macrophages) in the response to any infection or any damage is explained by the fact that microorganisms, their components, tissue necrosis products, blood serum proteins, substances secreted by other cells are chemoattractants for phagocytes. At the site of inflammation, the functions of phagocytes are activated. Macrophages replace microphages. In cases where the inflammatory reaction with the participation of phagocytes is not enough to cleanse the body of pathogens, then the secretory products of macrophages ensure the involvement of lymphocytes and the induction of a specific immune response.

Complement system. The complement system is a multicomponent self-assembled system of serum proteins that plays an important role in maintaining homeostasis. It is capable of being activated during the process of self-assembly, i.e., the sequential attachment of individual proteins, which are called components or complement fractions, to the resulting complex. Nine such factions are known. They are produced by liver cells, mononuclear phagocytes and are contained in the blood serum in an inactive state. The process of complement activation can be triggered (initiated) in two different ways, called classical and alternative.

When complement is activated in the classical way, the initiating factor is the antigen-antibody complex (immune complex). Moreover, antibodies of only two classes IgG and IgM in the composition of immune complexes can initiate complement activation due to the presence in the structure of their Fc fragments of sites that bind the C1 fraction of complement. When C1 joins the antigen-antibody complex, an enzyme (C1-esterase) is formed, under the action of which an enzymatically active complex (C4b, C2a) is formed, called C3-convertase. This enzyme breaks down S3 into S3 and S3b. When subfraction C3b interacts with C4 and C2, a peptidase is formed that acts on C5. If the initiating immune complex is associated with the cell membrane, then the self-assembled complex C1, C4, C2, C3 ensures the fixation of the activated fraction C5, and then C6 and C7, on it. The last three components jointly contribute to the fixation of C8 and C9. In this case, two sets of complement fractions - C5a, C6, C7, C8 and C9 - constitute a membrane attack complex, after which it attaches to the cell membrane, the cell is lysed due to irreversible damage to the structure of its membrane. In the event that complement activation along the classical pathway occurs with the participation of the erythrocyte-antierythrocyte Ig immune complex, hemolysis of erythrocytes occurs; if the immune complex consists of a bacterium and an antibacterial Ig, lysis of the bacteria occurs (bacteriolysis).

Thus, when activating complement in the classical way, the key components are C1 and C3, the cleavage product of which C3b activates the terminal components of the membrane attack complex (C5 - C9).

There is a possibility of activation of S3 with the formation of S3b with the participation of S3 convertase of the alternative pathway, i.e., bypassing the first three components: C1, C4 and C2. The peculiarity of the alternative pathway of complement activation is that initiation can occur without the participation of the antigen-antibody complex due to polysaccharides of bacterial origin - lipopolysaccharide (LPS) of the cell wall of gram-negative bacteria, surface structures of viruses, immune complexes including IgA and IgE.

dependent and oxygen-independent mechanisms of bactericidal activity. Opsonins. Methods

studying the phagocytic activity of cells.

Phagocytosis is a process in which blood cells specially designed for this purpose and

body tissues (phagocytes) capture and digest solid particles.

Carried out by two types of cells: granular cells circulating in the blood

leukocytes (granulocytes) and tissue macrophages.

Stages of phagocytosis:

1. Chemotaxis. In the phagocytosis reaction, a more important role belongs to the positive

chemotaxis. Products secreted act as chemoattractants

microorganisms and activated cells at the site of inflammation (cytokines, leukotriene

B4, histamine), as well as breakdown products of complement components (C3a, C5a),

proteolytic fragments of blood coagulation and fibrinolysis factors (thrombin,

fibrin), neuropeptides, fragments of immunoglobulins, etc. However, “professional”

Chemotaxins are cytokines from the chemokine group. Before other cells reach the site of inflammation

Neutrophils migrate, macrophages arrive much later. Speed

chemotactic movement for neutrophils and macrophages is comparable, differences in

arrival times are probably associated with different rates of activation.

2. Adhesion phagocytes to the object. Caused by the presence of phagocytes on the surface

receptors for molecules present on the surface of an object (its own or

contacted him). During phagocytosis of bacteria or old cells of the host body

recognition of terminal saccharide groups occurs - glucose, galactose, fucose,

mannose, etc., which are presented on the surface of phagocytosed cells.

Recognition is carried out by lectin-like receptors of the corresponding

specificity, primarily mannose binding protein and selectins,

present on the surface of phagocytes. In cases where the objects of phagocytosis

are not living cells, but pieces of coal, asbestos, glass, metal, etc., phagocytes

first make the absorption object acceptable for the reaction,

enveloping it with its own products, including components of the intercellular

matrix they produce. Although phagocytes are capable of absorbing various types of

“unprepared” objects, the phagocytic process reaches its greatest intensity

during opsonization, i.e. fixation on the surface of objects of opsonins to which phagocytes

there are specific receptors - for the Fc fragment of antibodies, components of the system

complement, fibronectin, etc.

3. Activation membranes. At this stage, the object is prepared for immersion.

Protein kinase C is activated and calcium ions are released from intracellular stores.

Sol-gel transitions in the system of cellular colloids and actino-

myosin rearrangements.

4. Dive. The object is enveloped.

5. Phagosome formation. Closing the membrane, immersing an object with part of the membrane

phagocyte inside the cell.

6. Phagolysosome formation. Fusion of the phagosome with lysosomes, resulting in

optimal conditions are formed for bacteriolysis and breakdown of the killed cell.

The mechanisms of bringing the phagosome and lysosomes closer together are unclear; there is probably an active

movement of lysosomes to phagosomes.

7. Killing and splitting. The role of the cell wall of the cell being digested is great. Basic

substances involved in bacteriolysis: hydrogen peroxide, products of nitrogen metabolism,

lysozyme, etc. The process of destruction of bacterial cells is completed due to the activity

proteases, nucleases, lipases and other enzymes whose activity is optimal at low

pH values.

8. Release of degradation products.

Phagocytosis can be:

Completed (killing and digestion were successful);

Incomplete (for a number of pathogens, phagocytosis is a necessary step in their life cycle, for example, in mycobacteria and gonococci).

Oxygen-dependent microbicidal activity is realized through the formation of a significant amount of products with toxic effects that damage microorganisms and surrounding structures. NLDP oxidase (flavoprotedo-cytochrome reductase) of the plasma membrane and cytochrome b are responsible for their formation; in the presence of quinones, this complex transforms 02 into the superoxide anion (02-). The latter exhibits a pronounced damaging effect, and is also quickly transformed into hydrogen peroxide according to the scheme: 202 + H20 = H202 + O2 (process

catalyzes the enzyme superoxide dismutase).

Opsonins are proteins that enhance phagocytosis: IgG, acute phase proteins (C-reactive protein,

mannan-binding lectin); lipopolysaccharide-binding protein, complement components - C3b, C4b; surfactant proteins of the lungs SP-A, SP-D.

Methods for studying the phagocytic activity of cells.

To assess the phagocytic activity of peripheral blood leukocytes, 0.25 ml of a microbial culture suspension with a concentration of 2 billion microbes in 1 ml is added to citrated blood taken from a finger in a volume of 0.2 ml.

The mixture is incubated for 30 minutes at 37°C, centrifuged at 1500 rpm for 5-6 minutes, and the supernatant is removed. A thin silvery layer of leukocytes is carefully sucked out, smears are prepared, dried, fixed, and painted with Romanovsky-Giemsa paint. The preparations are dried and microscopically examined.

The count of absorbed microbes is carried out in 200 neutrophils (50 monocytes). The intensity of the reaction is assessed using the following indicators:

1. Phagocytic indicator (phagocytic activity) - the percentage of phagocytes from the number of counted cells.

2. Phagocytic number (phagocytic index) - the average number of microbes absorbed by one active phagocyte.

To determine the digestive ability of peripheral blood leukocytes, a mixture of the taken blood and a suspension of the microorganism is prepared and kept in a thermostat at 37°C for 2 hours. Preparation of smears is similar. During microscopy of the preparation, viable microbial cells are increased in size, while digested ones are less intensely colored and smaller in size. To assess the digestive function, the indicator of phagocytosis completion is used - the ratio of the number of digested microbes to the total number of absorbed microbes, expressed as a percentage.

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