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What are igg antibodies? What does an immunoglobulin G test show?

Cytomegalovirus is a herpetic type microorganism that is opportunistic and latently lives in the bodies of 90% of people. When the immune system is weakened, it begins to actively multiply and leads to the development of infection. To diagnose the disease, an enzyme immunoassay for cytomegalovirus IgM is predominantly used - determining the presence of antibodies to the infectious agent in the blood.

Indications for the study

As a rule, cytomegalovirus does not pose a danger to a person with normal immunity and is asymptomatic; Sometimes mild symptoms of general intoxication of the body appear, which do not lead to the development of complications. However, for pregnant women and people with immunodeficiency, acute infection can be dangerous.

An enzyme immunoassay for antibodies to CMV is performed if the following symptoms are observed:

  • increased body temperature;
  • rhinitis;
  • sore throat;
  • enlarged lymph nodes;
  • inflammation and swelling of the salivary glands, in which the virus is concentrated;
  • inflammation of the genital organs.

Most often, cytomegalovirus is difficult to distinguish from a common acute respiratory disease. It is worth noting that a pronounced manifestation of symptoms indicates a weakened immune system, so in this case you should additionally check for immunodeficiency.

The easiest way to distinguish cytomegalovirus from a cold is by the timing of the disease. Symptoms of acute respiratory infections disappear within a week; herpes infection can remain in acute form for 1–1.5 months.

Thus, the indications for prescribing the analysis are as follows:

  1. Pregnancy.
  2. Immunodeficiency (caused by HIV infection, taking immunosuppressants, or congenital).
  3. The presence of the above symptoms in a person with normal immunity (the disease must first be differentiated from the Epstein-Barr virus).
  4. Suspicion of CMV in a newborn child.

Given the possible asymptomatic course of the disease, during pregnancy the test should be performed not only in the presence of symptoms, but also for screening.

The immune system first responds to the entry of any foreign microorganisms into the blood by producing antibodies. Antibodies are immunoglobulins, large protein molecules with a complex structure that are able to bind to proteins that make up the shell of viruses and bacteria (they are called antigens). All immunoglobulins are divided into several classes (IgA, IgM, IgG, etc.), each of which performs its own function in the body’s natural defense system.

IgM class immunoglobulins are antibodies that are the first protective barrier against any infection. They are produced urgently when the CMV virus enters the body, do not have a specification and have a short lifespan - up to 4–5 months (although residual proteins that have a low coefficient of binding to antigens may remain 1–2 years after infection).

Thus, an analysis for IgM immunoglobulins allows you to determine:

  • primary infection with cytomegalovirus (in this case, the concentration of antibodies in the blood is maximum);
  • exacerbation of the disease - the concentration of IgM increases in response to a sharp increase in the number of viral microorganisms;
  • reinfection - infection with a new strain of the virus.

Based on the remnants of IgM molecules, over time, IgG immunoglobulins are formed, which have a specification - they “remember” the structure of a particular virus, persist throughout life and do not allow the infection to develop unless the overall strength of the immune system is reduced. Unlike IgM, IgG antibodies against different viruses have clear differences, so analysis for them gives a more accurate result - they can be used to determine which virus has infected the body, while analysis for IgM only provides confirmation of the presence of infection in a general sense.

IgG antibodies are very important in the fight against cytomegalovirus, since it is impossible to completely destroy it with the help of medications. After the exacerbation of the infection ends, a small number of microorganisms remain in the salivary glands, on the mucous membranes, and internal organs, which is why they can be detected in samples of biological fluids using polymerase chain reaction (PCR). The virus population is controlled precisely by IgG immunoglobulins, which prevent cytomegaly from becoming acute.

Decoding the results

Thus, enzyme immunoassay makes it possible to accurately determine not only the presence of cytomegalovirus, but also the period elapsed since infection. It is important to evaluate the presence of both major types of immunoglobulins, so IgM and IgG antibodies are considered together.

The results of the study are interpreted as follows:

IgM IgG Meaning
– – A person has never encountered cytomegalovirus, so the immune system is “not familiar” with it. Considering that almost all people are infected with it, the situation is very rare.
– + Normal for most people. This means that there was contact with the virus in the past, and the body has developed a permanent defense against it.
+ – Acute primary infection - the infection occurred recently, “fast” immunoglobulins were activated, but there is no permanent protection against CMV yet.
+ + Exacerbation of chronic infection. Both types of antibodies are activated when the body has encountered the virus previously and has developed permanent protection, but it does not cope with its task. Such indicators indicate a serious weakening of the immune system.

Particular attention should be paid to a positive IgM antibody result in pregnant women. If IgG immunoglobulins are present, there is nothing to worry about; acute infection poses a danger to the development of the fetus. Complications in this case occur in 75% of cases.

In addition to the actual presence of antibodies, enzyme immunoassay evaluates the avidity coefficient of proteins - their ability to bind to antigens, which decreases as they are destroyed.

The results of the avidity study are deciphered as follows:

  • >60% - immunity to cytomegalovirus is developed, infectious agents are present in the body, that is, the disease occurs in a chronic form;
  • 30–60% - relapse of the disease, an immune response to the activation of a virus that was previously in a latent form;
  • <30% - первичное инфицирование, острая форма заболевания;
  • 0% - no immunity, there was no CMV infection, there are no pathogens in the body.

It should be borne in mind that a person with a strong immune system does not need to worry about positive test results - cytomegalovirus does not require drug treatment, the body is quite capable of coping with the infection on its own. However, if the results indicate an acute phase of the disease, you should limit contact with healthy people, especially pregnant women, as there is a high probability of spreading the virus.

Positive IgM result during pregnancy

For women planning a pregnancy or already carrying a child, it is very important to know about a past infection with cytomegalovirus, as this can affect the development of the fetus. An enzyme immunoassay for antibodies comes to the rescue with this.

Test results during pregnancy are assessed differently. The safest option is positive IgG and negative IgM - there is nothing to worry about, since the woman has immunity against the virus, which will be passed on to the child, and there will be no complications. The risk is also small if positive IgM is detected - this indicates a secondary infection that the body is able to fight, and there will be no serious complications for the fetus.

If no antibodies of either class are detected, the pregnant woman should be very careful. It is important to follow measures to prevent infection with cytomegalovirus:

  • avoid sexual intercourse without using contraception;
  • avoid sharing saliva with other people - do not kiss, do not share dishes, toothbrushes, etc.;
  • maintain hygiene, especially when playing with children, who, if they are infected with cytomegalovirus, are almost always carriers of the virus, since their immunity is not yet fully formed;
  • See a doctor and get tested for IgM for any manifestations of cytomegalovirus.


It is important to remember that it is much easier to become infected with the virus during pregnancy due to the fact that a woman’s immunity naturally weakens during pregnancy. This is a mechanism of protection against rejection of the embryo by the body. Like other latent viruses, old cytomegalovirus can become active during pregnancy; this, however, only in 2% of cases leads to infection of the fetus.

If the result for IgM antibodies is positive and for IgG antibodies is negative, the situation is most dangerous during pregnancy. The virus can enter the fetus and infect it, after which the development of the infection may vary depending on the individual characteristics of the child. Sometimes the disease is asymptomatic, and permanent immunity against CMV develops after birth; in 10% of cases, the complication is various pathologies of the development of the nervous or excretory system.

Particularly dangerous is infection with cytomegalovirus during pregnancy of less than 12 weeks - an underdeveloped fetus cannot resist the disease, which leads to miscarriage in 15% of cases.

An IgM antibody test only helps determine the presence of the disease; The risk to the child is assessed through additional tests. Based on a number of factors, appropriate pregnancy management tactics are developed to help minimize the likelihood of complications and congenital defects in the child.

Positive result in a child

An embryo can become infected with cytomegalovirus in several ways:

  • through sperm during fertilization of the egg;
  • through the placenta;
  • through the amniotic membrane;
  • during childbirth.

If the mother has IgG antibodies, then the child will also have them until about 1 year of age - initially they are there, since during pregnancy the fetus shares a common circulatory system with the mother, then it is supplied with breast milk. As breastfeeding stops, the immune system weakens and the child becomes susceptible to infection from adults.

Positive IgM in a newborn indicates that the child was infected after birth, but the mother does not have antibodies to the infection. If CVM is suspected, not only an enzyme-linked immunosorbent assay is performed, but also PCR.

If the child’s body’s own defenses are not enough to fight the infection, complications may develop:

  • slowdown in physical development;
  • jaundice;
  • hypertrophy of internal organs;
  • various inflammations (pneumonia, hepatitis);
  • lesions of the central nervous system - mental retardation, hydrocephalus, encephalitis, problems with hearing and vision.

Thus, the child should be treated if IgM antibodies are detected in the absence of IgG immunoglobulins inherited from the mother. Otherwise, the body of a newborn with normal immunity will cope with the infection on its own. Exceptions are children with serious oncological or immunological diseases, the course of which may affect the functioning of the immune system.

What to do if the result is positive?

A person’s body with a healthy immune system is able to cope with the infection on its own, so if an immune response to cytomegalovirus infection is detected, nothing can be done. Treatment of a virus that does not manifest itself in any way will only lead to a weakening of the immune system. Medicines are prescribed only if the infectious agent begins to actively develop due to an insufficient response of the body.

Treatment is also not necessary during pregnancy if there are IgG antibodies. If only the IgM test is positive, medication is necessary, but it is intended to contain the acute infection and convert the cytomegalovirus into a latent form. It should be remembered that medications for CMV are also unsafe for the body, so they can only be used if prescribed by a doctor - self-medication will lead to various adverse consequences.


Thus, positive IgM indicates an active stage of CMV infection. It should be considered in conjunction with other test results. Particular attention to the test indications should be paid to pregnant women and people with weakened immune systems.

TORCH infections

A special place among human infectious diseases is occupied by the so-calledTORCH-infections. "ToRCH" is an abbreviation of the Latin names of four infections: Toxoplasmosis (Toxolasmosis), Rubella (Rubella), Cytomegalia (CMV), Herpes simplex (Their peculiarity lies in their widespread prevalence and the absence, as a rule, of a clearly defined clinical picture, in the predominance of latent forms of the disease, which can develop into acute or subacute forms against the background of secondary immunodeficiencies caused by both physiological (pregnancy) and pathological reasons. With primary infection and reactivation of latent infection during pregnancy, intrauterine infection may occur, leading to miscarriage, stillbirth, developmental defects, disability and even death of the child. In this regard, the role of timely laboratory diagnostics is important.TORCH-infections in women of childbearing age and pregnant women.

When is it appropriate to conduct research for TorCH infection:

    Planning and preparation for pregnancy;

    Monitoring the effectiveness of treatment;

    During pregnancy (over time) with established infection with one of the pathogens of TORCH infection;

    Specific inflammatory processes of the genitals, infertility of unknown origin;

    Miscarriage;

    History of congenital deformities;

    The birth of children with signs of intrauterine infection and congenital pneumonia.

    Low-grade fever of unknown etiology (unclear prolonged increase in body temperature to 37.5 WITH);

    Generalized enlargement of lymph nodes, hepatolienal syndrome (enlarged liver and spleen)

    Damage to the central nervous system (encephalitis, arachnoiditis, polyradiculo and polyneuropathy), eye damage of the uveitis type.

Algorithm for examining women planning pregnancy.

1. All subjects are tested for the presence of specific antibodies of class G (IgG).

2. In case of a positive result, there is no risk of intrauterine infection. Further testing is not advisable.

3. In case of a negative result, the woman is considered a risk group during pregnancy and is periodically (every 8-12 weeks) tested for the presence of specific antibodies of class M (IgM).

4. A positive result for IgM will indicate a primary infection and a high risk of vertical infection.

Examination during pregnancy

If a woman has not been examined before pregnancy and her serological status is unknown, then she should be periodically (every 8-12 weeks) examined for the presence of specific class M antibodies (IgM).

Newborn examination

The diagnosis of congenital, rubella, CMV or HVI is confirmed only by the presence of appropriate specific antibodies of class M (IgM).

It must be remembered that the risk of intrauterine infection is very high only during primary infection(50%). During the latent (hidden) period, and even during the period of reactivation of the infection, intrauterine infection unlikely(0.1-0.5%). Therefore, in order to assess how favorable the pregnancy will be It is important to establish not only the presence or absence of infection, but the stage at which it is located.Indicators of primary infection are specific antibodies of class M (IgM), which usually appear in the blood in the second week after infection and disappear after 2-3 months. IgM may also appear during exacerbations (but not always). They are replaced by class G (IgG) antibodies in the blood, which only increase in the first 2-3 months of the disease. For some time (6-12 months), the IgG titer remains stable, then decreases somewhat, but never completely disappears. In fact, IgG can only indicate that a person has already had (it is not known when) contact with the infection. At the same time, a single determination of the titer does not allow distinguishing primary infection from past infection or asymptomatic carriage. Determining the stage of infection requires comparison of antibody titers in patient blood samples collected at specified intervals. When using this approach, you may encounter the following difficulties:

    There are cases of an atypical course of the immune response, when IgM is present in the blood for a short time, or is not formed at all, or, on the contrary, trace amounts of IgM are detected in the blood up to one to two years after infection;

    the specificity of test systems for identifying species-specific IgM may not be absolute due to the presence of rheumatoid factor in the blood or nonspecific interaction of IgM with the immunosorbent;

    If the patient is not hospitalized, regular blood sampling may be difficult.

In this case, it is effective to use the method of determining the avidity-specific indexIgG.During the body’s immune response to the penetration of an infectious agent, the stimulated clone of lymphocytes begins to produce first specific IgM antibodies, and somewhat later specific IgG antibodies. IgG antibodies initially have low avidity, that is, they bind the antigen quite weakly. Then the development of the immune process gradually (this can be weeks or months) moves towards the synthesis by lymphocytes of high-avidity IgG antibodies, which bind more firmly to the corresponding antigens. The high avidity of specific IgG antibodies allows one to exclude recent primary infection. The results are given as a percentage of the so-calledavidity index( IA) .

The detection of antibodies in the test serum with a mavidity index below 40% (values ​​may differ from one manufacturer to another) indicates a fresh primary infection of the examined patient. A detected avidity index greater than 60% indicates that the serum contains high avidity antibodies, indicating a past infection. An antibody avidity index in the range of 41-60% indicates a late stage of primary infection (and the titerIgGlow), recent activation of the virus in the body or secondary infection. In the second and third cases, the concentrationIgGhigh.

Table1. Interpretation of the avidity index.

Result

Meaning

Interpretation

<40%

low-avidity

Confirms the fact of acute infection from 10 to 100 days ago

41-60%

transitional

Confirms the fact of acute infection from 101 to 160 days ago

>60%

highly avid

More than 161 days have passed since acute infection or exposure, antibodies are protective

ATTENTION! Calculation of the avidity index should be carried out for sera previously tested for the presence of species-specific antibodies of the class ( IgG ).

TOXOPLASMOSIS

Laboratory diagnosis of toxoplasmosis is based only on the determination of specific antibodies, since the Toxoplasma gondii antigen is present in the blood for a very short time. When the pathogen enters the human body, the primary immune response begins within 7-14 days - the production of IgM antibodies. The maximum level of IgM antibodies is reached by the 20th day from the onset of the disease. Their complete disappearance in most cases occurs within 3-4 months. During the same period, maximum values ​​of IgG antibodies are observed in the blood. After recovery, there is a gradual decrease in the titer of IgG antibodies to a certain level, which persists for life and indicates the presence of stable immunity.

When determining IgG and IgM antibodies to toxoplasmosis in blood serum, the following results are possible:

    +IgG, -IgM – indicates asymptomatic healthy carriage (up to 30% of the adult population). This combination of antibodies in the blood of pregnant women does not pose a threat to the fetus.

    -IgG, +IgM or +IgG, +IgM – primary infection, acute or subclinical course.During pregnancy, this situation indicates the possibility of intrauterine infection. In doubtful cases, the test must be repeated after 7-14 days to confirm seroconversion.

    – IgG, -IgM – no infection. Pregnant women with this result should be included in the risk group and examined every trimester.

RUBELLA

To establish a diagnosis, IgM antibodies are determined in the blood serum, the maximum titer of which is observed 2-3 weeks from the onset of the disease, and their complete disappearance occurs after 1-3 months. IgG antibodies are determined from the 7th day of the disease, and the maximum titer - on the 21st day. Then the titer decreases to a certain level, indicating stable immunity.

The following combinations of IgG and IgM antibodies in blood serum are possible:

    +IgG, -IgM – indicates a previous illness and stable immunity.Immunity is developed as a result of clinically expressed and asymptomatic forms. Recently, evidence has emerged that immunity after rubella is not as strong as previously thought, since adults sometimes get rubella (5% of cases), despite the fact that they had it in childhood. In this case, an increase in virus-neutralizing antibodies (IgG) is observed in the blood serum.

    -IgG, +IgM or +IgG, +IgM – primary infection, acute form or asymptomatic course, which is observed in 30% of cases. In this situation, there is a high risk of intrauterine infection. If infected in the first trimester, termination of pregnancy is recommended. In doubtful cases, the test should be repeated after 7-14 days to confirm seroconversion.

    -IgG, -IgM – lack of immunity. According to the latest data, 10-20% of women of childbearing age are not immune to the rubella virus. Therefore, it is necessary to examine women before pregnancy and, in the absence of immunity, recommend vaccination. Pregnant women who do not have IgG antibodies to the rubella virus are included in the risk group and are examined every trimester.

Cytomegalovirus infection (CMVI)

Laboratory diagnosis of CMV is based on the determination of specific antibodies in blood serum and other biological fluids, along with various methods for determining the antigen and DNA of the virus. The presence of specific IgG and IgM class antibodies in the blood depends on the form and stage of CMV.

Primary infection (active stage)

Latent form (inactive stage)

Active form

Persist.

Reactivation

Superinfo.

Clinical symptoms

IgG antibodies

IgM antibodies

Isolation of viral DNA

Risk of transmission from mother to fetus (in points)

The following combinations of IgG and IgM antibodies are possible for CMV infection:

    -IgG, -IgM – no infection. It is observed in 5-10% of the adult population. Pregnant women who do not have IgG antibodies to CMV are included in the risk group and are examined every trimester.

    ±IgG, +IgM – primary infection. Primary CMV infection, which occurs in pregnant women in 1-4% of cases, is accompanied by a greater risk of infection of the fetus than reactivated CMV infection.

    +IgG, ±IgM – persistent infection, reactivation. Can be considered as an indirect sign of viremia and exacerbation of infection. The risk of fetal infection is 0.5-2.5%. In most cases, CMV infection is asymptomatic, and the woman’s history contains information about adverse pregnancy outcomes: miscarriages, stillbirths, births of children with developmental defects.

    +IgG, -IgM – . It has been established that the presence of specific IgG antibodies against CMV in the patient’s blood indicates his infection rather than protection from infection. This situation does not pose an immediate danger to the fetus, but since a state of physiological immunodeficiency develops during pregnancy, both seropositive and seronegative women should be included in the risk group.

Herpes virus infection (HVI)

Laboratory diagnosis of HVI includes the determination of specific antibodies to the herpes simplex virus (HSV) in the blood serum along with the determination of the HSV antigen in blood cells, urine sediment, and saliva. When making a diagnosis, it is necessary to take into account laboratory data and clinical symptoms.

The following options are possible when determining specific antibodies to HSV:

    -IgG, -IgM – no infection. It is observed in 5-10% of the adult population. Pregnant women who do not have IgG antibodies to HSV are included in the risk group and are examined every trimester.

    ±IgG, +IgM – primary infection. Clinical symptoms are detected in 33% of cases. Transplacental transmission is possible. The risk of infection of a child during childbirth is 50-70%. HSV is transmitted through the placenta in 10 times less common than cytomegalovirus.

    +IgG, ±IgM – persistent infection, reactivation. As with CMV, it can be considered as an indirect sign of viremia and exacerbation of infection. In this case, during pregnancy the risk of infection of the fetus is 5%. In most cases, HPHI has an atypical course, and the woman’s history contains information about adverse pregnancy outcomes: miscarriages, stillbirths, births of children with developmental defects. Women with such a history should be examined before pregnancy.

    +IgG, -IgM – infection, remission state. It has been established that the presence of specific IgG antibodies to HSV, as with CMV, in the patient’s blood indicates his infection rather than protection from infection. This situation does not pose an immediate danger to the fetus, but since a state of physiological immunodeficiency develops during pregnancy, both seropositive and seronegative women should be included in the risk group (primary infection and exacerbation of GVI are possible). If necessary, both spouses are examined.

There are quite a lot of methods for studying human blood to diagnose and identify any diseases. can be prescribed either according to indications or without fail. The medical name for antibodies is immunoglobulins. Let's try to figure out what they are, why they are needed and how they work. Immunoglobulin is a serum that is produced by protective cells - lymphocytes in response to invasion of the body by a foreign microorganism. From the moment of birth, a person is constantly faced with a foreign environment, and his immune system must be on alert. Antibodies are the “soldiers” of immunity.

How are they produced?

When an antigen first enters the body, special cells of the immune system recognize it, “decode” it, after which the process of producing counteracting cells starts. This preparatory period takes several days, and after 7-10 days the amount of antibodies in the blood reaches its maximum.

The lifespan of antibodies in human blood varies. For example, after suffering from the flu, the presence of immunoglobulins is observed for a year to a year and a half, after an acute respiratory viral infection - for several months, after chickenpox - for life. The presence of antibodies in a person’s body does not mean protection from re-infection, it is protection from recurrent disease.

They are able to remember aggressive agents and upon their subsequent penetration, the production of antibodies occurs much faster, and the disease does not have time to develop.

Antibodies not only fight microorganisms (viruses, bacteria and others), but are also produced when exposed to allergens, and neutralize dead cells of one’s own tissues.

Classification

According to the worldwide classification, it is customary to distinguish five types of antibodies:

Detection of an increased concentration of immunoglobulins of one or another group in the blood can tell a lot about the processes occurring in the body, even if they do not yet show symptoms.

  1. For infectious diseases it is important:
    • attack, what infectious microorganism the person was exposed to;
    • whether the immune system is coping successfully or whether it requires help in the form of drug therapy;
    • at what stage is the disease, and is there a risk of it becoming chronic;
    • primary or re-infection has occurred.
  2. When planning a pregnancy, the necessary indicator is antibodies to the Rh protein, which determines the gestation and development of the fetus, as well as methods of pregnancy management.
  3. finds out to which antigen the body shows increased sensitivity, based on this, treatment is based.
  4. If cancer is suspected, this antibody test confirms or refutes these suspicions by the presence or absence of antibodies to malignant cells.

How is the analysis performed?

Can be done on any hand. To ensure the reliability of the research result, it is better to carry out preparation within two to three days:

  • stop taking medications, if these are life-sustaining drugs, you must inform your doctor about them;
  • exclude physical activity and the effects of physiotherapy;
  • dietary nutrition is introduced (exclusion of spicy, fried foods, alcohol, tonic drinks);
  • in the morning;
  • refrain from nicotine for two hours before the test;
  • Blood testing for antibodies is not given immediately after an infectious disease or a violent allergic reaction.

Decoding

Antibodies are tested for the three main immunoglobulins responsible for the formation and maintenance of immunity - IgA, IgM, IgG. Each of them has its own norms for different age groups. IgA, normal for children – 0.15 – 2.5; for adults – 0.4 – 3.5.

Promotion and relegation

An increase in antibodies in the adult body is observed when:

  • acute respiratory infections;
  • inflammation of the mucous membranes of the gastrointestinal tract and urinary tract;
  • liver diseases;
  • skin infections;
  • malignant lesions of the lymphatic system and the blood itself.

Antibody decline occurs:

  • chronic inflammatory processes;
  • immunodeficiency states;
  • renal failure;
  • taking immunosuppressants.

IgM, the norm in children is 0.7 – 1.5; for women – 0.7 – 2.9; for men – 0.5 – 2.5.

The decrease is observed:

  • condition after radiation therapy;
  • condition after removal of the spleen;
  • extensive burns.

IgG, norm for children – 7.0 – 13.0; for adults – 7.0 – 16.0.

The decrease is detected:

  • allergic manifestations;
  • conditions after removal of the spleen;
  • pathological conditions of the kidneys;
  • radiation exposure;
  • taking immunosuppressants.

A blood test for IgE is prescribed when allergic reactions are suspected and to identify the antigen.

Vaccination

One way to train the immune system is vaccination. The essence of this method is to introduce severely weakened or dead cells of an “enemy agent” into the body. In response to this, IgM antibodies are produced, which destroy these cells, and IgG, which remember the enemy himself and how to fight him. Repeated administration (re-vaccination) forms final lifelong immunity. As a result, the immune system is prepared to meet the real virus and responds quickly and efficiently.

Thanks to vaccination, the number of outbreaks of childhood infectious diseases (measles, polio, rubella) has noticeably decreased, and particularly dangerous infections such as smallpox and plague have been completely suppressed.

The debate about the need for mass immunization has been going on for many years. Both supporters and opponents of vaccination make strong arguments.

A striking example of the use of antibodies in diagnostics is the Mantoux test. To do this, a dose of tuberculin is injected intradermally into the person - these are not living microorganisms, but only a product of their vital activity, so it is not possible to become infected with tuberculosis when they are administered.

Antibodies of class M and class G react to tuberculin. Moreover, if there is immunity, that is, if a person is infected or has had this disease, the reaction will be more violent than usual. Therefore, it is assessed in dynamics, in comparison with previous results. The diagnostic accuracy ranges from 70 to 80%.

A positive result for antibodies does not necessarily indicate the development of the disease; it may be a hyperreaction to tuberculin, as to an allergen, or may indicate a well-developed immune system. If a positive result is detected, an additional examination is prescribed: chest x-ray and Pirquet's test.


During pregnancy

The most important thing is to identify antibodies to, it is equally important to know whether a pregnant woman has immunity to rubella or not.

The body of a Rh-negative woman is capable of rejecting a fetus that has Rh protein, perceiving it as a foreign microorganism. develops during the second and subsequent pregnancies, when the female body is already sensitized. The detection of positive antibodies to the Rh protein in a woman’s blood allows timely implementation of the necessary measures to maintain pregnancy and prevent fetal death.

Why is a rubella antibody test performed? This childhood infectious disease is dangerous not so much for the pregnant woman herself as for the unborn child. If neither IgM nor IgG are found in the blood, it means that the woman has no immunity, and in case of illness, the fetus will be affected by the virus in 70–90% of cases. If the mother has immunity, the disease does not pose a threat to the baby, even if the mother becomes infected.

If there are several cases of spontaneous abortion in the anamnesis, the woman is prescribed a test for antibodies to phospholipids. This pathology is caused by genetic predisposition and autoimmune diseases.

Antibody determination

When hospitalized in a hospital, testing for antibodies to blood-borne diseases is mandatory. This is important to prevent hospital-acquired infection of both other patients and medical personnel. These diseases include: viral and B, HIV infection. Immunoglobulins for them begin to be produced in the latent (hidden) stage, when no external manifestations are detected.

Indications for blood tests

It makes it possible to determine not only the presence or absence of this disease, but also the stage of development. Determination of antibodies to cytomegalovirus is important when planning pregnancy.

Allergy tests are the detection of immunoglobulins produced as a hypersensitive reaction to contact with an antigen. Moreover, there is an increase in IgE, which normally practically does not occur in childhood, but increases significantly in quantity over the years.

Blood testing for antibodies is used for diagnosis and monitoring of diseases of the thyroid gland, stomach and intestines, joint diseases, and autoimmune diseases. This method is widely used in the diagnosis of TORCH infections.

The question of the normal level of IgG immunoglobulins to cytomegalovirus in the blood serum worries most women planning pregnancy or already carrying a child, as well as many young mothers. The increased attention to the virus in recent years is explained by its widespread prevalence in the human population and the negative impact on fetal development when the expectant mother is infected during pregnancy. In addition, cytomegalovirus infection (CMVI) is often associated with the development of atypical pneumonia in children, delayed physical and mental development, visual and hearing impairment.

CMV infection is also of particular importance in organ transplantation and the treatment of immunocompromised patients.

Determining the level of IgG antibodies in the blood is the most common method for detecting cytomegalovirus infection and determining its status in the body. It is important to understand that the content of immunoglobulins G in blood serum is expressed in relative units, which may vary depending on the location of the laboratory performing the analysis and the equipment used.

Accordingly, the numerical expression of the norm may look different. The very presence of IgG in the body of adults is considered normal, since more than 90% of the world’s population are carriers of the virus. In this case, the production of antibodies indicates a normal response of the immune system to infection with the virus.

The detection of IgG antibodies in a patient’s blood has a certain diagnostic value: this in itself is not an indication for treatment, but only indicates the presence of immunity to infection. That is, the body has already encountered the virus at some point and produces (for life) the corresponding antibodies.

What is the norm

The amount of antibodies to cytomegalovirus is usually expressed as a titer. The titer is the highest dilution of the patient's blood serum at which a positive reaction is observed. As a rule, for immunological studies, serum dilutions are prepared in multiples of two (1:2, 1:4, and so on). The titer does not reflect the exact number of immunoglobulin molecules in the blood, but gives an idea of ​​their total activity. This significantly speeds up obtaining analysis results.

There is no standard for the titer value, since the amount of antibodies synthesized by an individual human body can vary depending on the general condition of the body, lifestyle, activity of the immune system, the presence or absence of chronic infections, and metabolic characteristics.

To interpret the results of an analysis for antibodies to cytomegalovirus, the concept of “diagnostic titer” is used. This is a certain dilution of blood serum, a positive result in which is considered an indicator of the presence of the virus in the body. For cytomegalovirus infection, the diagnostic titer is a dilution of 1:100.

Currently, the arsenal of immunological laboratories has several dozen test systems for determining antibodies to cytomegalovirus. They all have different sensitivity and consist of different components. The only thing that is common is the principle of the study - enzyme-linked immunosorbent assay (ELISA).

The ELISA results are recorded based on the degree of coloration (optical density) of the solution to which the patient’s serum is added. The optical density (OD) of the analyzed sample is compared with obviously positive and negative samples - controls.

As a rule, to speed up the study, each test system is configured to work with one dilution of blood serum specified in the instructions for the test system. This eliminates the need to prepare multiple dilutions, and the analysis procedure is shortened by several hours.

There is currently no uniform diagnostic titer for all laboratories. For each test system, the manufacturer indicates the so-called reference values ​​at which the result is considered positive or negative.

That is why in the forms of test results for antibodies to cytomegalovirus you can find the following: norm - 0.3, result - 0.8 (positive). In this case, the norm means the optical density of the control sample, which does not contain antibodies to the virus.

Details about immunoglobulins IgG and IgM

When cytomegalovirus enters the body, a nonspecific cellular component of immunity is initially activated - phagocytic cells (macrophages and neutrophils). They capture and neutralize the virus. The protein components of the virus envelope appear on the membranes of macrophages. This serves as a signal for a special group of T-lymphocytes - helpers, which secrete specific stimulators of B-lymphocytes. Under the influence of the stimulator, B lymphocytes begin active synthesis of immunoglobulins.

Immunoglobulins (antibodies) are soluble proteins that circulate in the blood and tissue intercellular fluid, and are also present on the surface of B lymphocytes. They provide the most effective and rapid protection against the proliferation of infectious agents in the body, are responsible for lifelong immunity to certain infections and are involved in the development of protective inflammatory and allergic reactions.

There are five classes of antibodies - IgA, IgM, IgG, IgD, IgE. They differ from each other in structure, molecular weight, strength of binding to antigens and types of immune reactions in which they take part. In antiviral protection against CMV infection, immunoglobulins of classes M and G are of greatest importance.

IgM is the first to be synthesized when the body is infected with a virus.. They appear in the blood within 1-2 weeks after the initial infection and persist from 8 to 20 weeks. The presence of these antibodies in the blood serum usually indicates a recent infection. Class M immunoglobulins can also appear during reactivation of an old infection, but in much smaller quantities. In this case, it is possible to distinguish a primary infection from a reactivated one by determining the avidity of antibodies, that is, the strength of their binding to viral particles.

IgG immunoglobulins appear in blood serum approximately a month after infection with cytomegalovirus. At the beginning of the immune response they have low avidity. 12-20 weeks after the onset of infection, avidity becomes high. IgG remains in the body for life and allows the immune system to quickly respond to increased virus activity.

The amount of immunoglobulins synthesized depends on the individual characteristics of the organism, so there are no normal values ​​for this indicator. In most people with normal immune system activity, the amount of IgG to cytomegalovirus increases rapidly during the first 4-6 weeks after primary infection or reactivation of the infection, then gradually decreases and remains at a constant level.

Decoding the analysis results

In order to independently decipher the results of the analysis for cytomegalovirus, it is necessary to compare the data obtained with the reference values ​​​​indicated in the response form. These indicators can be expressed in conventional units (a.u., IU), optical units (op.u.), optical density indicators (OD), units per milliliter or as a titer. Examples of results and their interpretation are given in the table.

Possible options for the results of determining IgG in blood serum and their interpretation:

Reference values ​​(norm)

Patient serum

Result

There is no virus

There is a virus

Negative index 1.0

There is a virus

Positive Control >1.2

There is a virus

There is a virus

OP syv: 0.5 – negative

0.5-1 – doubtful

>1 – positive

Doubtful

There is a virus

If the form does not indicate reference values ​​or normal indicators, the laboratory is required to provide a transcript. Otherwise, the attending physician will not be able to determine the presence or absence of infection.

High IgG titers do not indicate danger to the body. Determining only class G immunoglobulins gives an idea of ​​the body's possible contact with cytomegalovirus in the past, but does not allow one to determine the activity of the virus. Thus, if IgG is detected in the patient’s blood serum, this only indicates that they are carriers of the virus.

To determine the stage of infection, the level of IgG avidity must be assessed. Low-avidity antibodies always indicate a fresh primary infection, while high-avidity antibodies circulate in the blood of virus carriers throughout their lives. When a long-standing chronic infection is reactivated, high-avidity IgG is also detected.

A complete picture of the picture can be obtained by a combination of immunological and molecular biological diagnostic methods: ELISA for antibodies of classes M and G to cytomegalovirus, IgG avidity, polymerase chain reaction (PCR) for the presence of viral DNA in the blood, saliva and urine.

Norm of IgG antibodies to cytomegalovirus in pregnant women

Testing for the presence of IgG to cytomegalovirus is mandatory when examining pregnant women. It has been proven that primary infection of the expectant mother can lead to spontaneous abortion, the development of severe congenital anomalies in the fetus, or long-term complications of the infection.

In this regard, you should not neglect mandatory tests and take them within the required time frame. It is advisable to take a cytomegalovirus test before 10-12 weeks of pregnancy. If a re-examination is recommended, it must be completed strictly within the specified time frame.

The ideal option is to determine antibodies to cytomegalovirus when planning pregnancy and in each trimester. This makes it possible to exclude or timely detect primary infection or reactivation of an old infection during pregnancy.

If a woman did not have antibodies to cytomegalovirus before pregnancy, she is at risk. When infected with the virus during pregnancy, the probability of intrauterine infection of the fetus reaches 50%. It is recommended to limit contact with children under 6 years of age and carefully observe personal hygiene rules.

If class G antibodies with low avidity and/or IgM are detected before pregnancy, a diagnosis of “recent primary infection” is made. It is recommended to delay conception for 2-3 months due to the high probability of infection of the fetus.

If a woman does not have antibodies to cytomegalovirus before pregnancy, but IgG is detected in her blood during pregnancy, this also indicates a primary infection. It is recommended to consult an infectious disease specialist and carefully monitor the health of the newborn, since the possibility of congenital infection cannot be excluded.

In practice, they are most often limited to a single determination of IgG and IgM in the first trimester of pregnancy, when the risk to the fetus is greatest. An immunoglobulin M test is necessary to determine the timing of infection. If this is not possible, a determination of IgG avidity is required.

Detection of class G immunoglobulins alone does not provide a complete picture of the duration of infection and the activity of the infectious process. The most accurate results can be obtained by performing all three analysis options: determination of IgG, IgM and IgG avidity.

Interpretation of test results for determining antibodies to cytomegalovirus in pregnant women and prognosis for the child:

IgG avidity

Risk to the fetus

Recent primary infection

High probability of infection

Not determined

Not defined

Possible long-standing latent infection or late stage of recent primary infection

Not determined

Not determined

See above and/or definition of IgM

Reactivation of latent infection

+ (increase in titer during double examination)

Reactivation of latent infection

Low chance of infection

+ (no increase in titer during double examination)

Long-standing latent infection

Virtually absent

No previous contact with the virus or a test taken within 7-14 days after the initial infection

Not defined

Re-examination is required in 2-3 weeks

If questionable results are obtained or in the case of immunodeficiency conditions, it is recommended to confirm the diagnosis by PCR (polymerase chain reaction).

Possibility of superinfection in the presence of immunoglobulins G in the blood

As a rule, the immune system of adults and children over 5-6 years of age effectively suppresses the activity of cytomegalovirus in the body, and the infection occurs without clinical manifestations.

However, this virus is characterized by great genetic variability, which leads to frequent changes in the structure of its proteins. The human immune system is highly specific, that is, in response to the introduction of a virus, antibodies are formed that have an affinity for the specific structure of its components. With significant modification of viral proteins, the strength of the immune response is reduced, so in rare cases, carriers of cytomegalovirus may have a primary infection caused by a modified version of the virus.

It should be remembered that if the result is positive for cytomegalovirus, you should not immediately sound the alarm. An asymptomatic infection does not pose a threat to an adult organism and does not require treatment. Pregnant women and women planning pregnancy, as well as persons with clinical manifestations of CMV infection, need to consult an infectious disease specialist.

Doctor's explanations about IgG and IgM to cytomegalovirus

General information about the study

The first immunoglobulins produced at the beginning of the immune response to the entry of a foreign antigen into the body are antibodies of the IgM class. Their formation does not require the additional participation of T-helper lymphocytes, which are responsible for switching synthesis to other classes of immunoglobulins, which allows the body to quickly launch the humoral immune mechanisms of defense.

IgM predominantly circulates in the bloodstream and makes up 5-10% of all blood immunoglobulins. IgM is a pentamer - it consists of five subunits, each of which has two antigen-binding centers. The half-life of IgM in the body is 5 days. These antibodies bind to antigens, opsonize and enhance their phagocytosis, and activate the complement system along the classical pathway. IgM, due to its large molecular weight, is not able to penetrate the placenta from mother to fetus, therefore, its increased amount to a certain antigen indicates intrauterine infection of the fetus. IgM includes blood group isohemagglutinins (antiA and antiB), heterophilic antibodies and early rheumatoid factor.

Specific IgM are produced in response to exposure to a specific antigen. They begin to be synthesized upon initial contact with an infectious agent or foreign substance, several days earlier than the first IgG antibodies appear. The amount of IgM increases during the first weeks after infection and gradually decreases until it disappears completely. IgM is replaced by IgG, which provide long-term protection against infections.

Excessive production of immunoglobulin M may be associated with hyperstimulation of all plasma cell clones or a specific clone of IgM-producing B cells. This may accompany an active infectious process or certain types of immunoproliferative diseases (for example, myeloma, Waldenström's macroglobulinemia).

IgM deficiency can be primary (congenital), which is rare, or secondary (acquired), caused by various factors that deplete humoral immunity.

What is the research used for?

  • To assess humoral immunity.
  • For the diagnosis of immunodeficiency conditions.
  • For differential diagnosis of acute and chronic infections (with simultaneous determination of IgG levels).
  • For the diagnosis of intrauterine infections.
  • For the diagnosis of Waldenström macroglobulinemia.
  • To assess the immune system in autoimmune pathologies, blood diseases and neoplasms.
  • To assess the effectiveness of immunoglobulin preparations.

When is the study scheduled?

  • When examining children and adults who often suffer from infectious diseases.
  • When monitoring the treatment of Waldenström macroglobulinemia.
  • When examining patients with autoimmune pathology.
  • In a comprehensive study of the immune system.
  • For neoplasms of hematopoietic and lymphoid tissues.
  • When monitoring patients with immunodeficiencies.
  • Before using immunoglobulin preparations, as well as during and after it.