Otitis

Pseudoallergy manifestations and pathogenetic differences from true allergies. “Pseudo-allergy” or why the allergen analysis did not give results? Foods that provoke false allergic reactions

According to statistics, more than half of the entire population of the planet has to deal with such a problem when they have obvious manifestations of allergies, but when they take tests and tests for allergens, the results turn out to be negative (that is, the allergen is not detected). Why is this happening? Is the analysis result unreliable? The laboratory should not be blamed in such cases, since in most cases it is a pseudo-allergy, which occurs without the presence of antibodies and is accompanied by symptoms almost identical to those of a true allergy.

This article will answer many questions, and you will be able to find out why pseudo-allergies occur, how they manifest themselves, are identified and treated.

Pseudo-allergy (or false allergy) is a condition in which there is an increased sensitivity of the body to certain substances entering it from the outside and symptoms characteristic of a true allergic reaction occur. With this pathology, the immunological phenomena that develop with allergies do not occur, and inflammation becomes a consequence of impaired histamine metabolism, improper activation of complement, and others. pathological mechanisms. This means that the substance that provokes allergic reactions is not an antigen in pseudoallergy, and the synthesis of immunoglobulins inherent in a true allergic reaction does not occur.

Most often, pseudoallergic processes begin after ingesting various foods, medications or nutritional supplements. After they enter the body, inflammatory mediators immediately enter the bloodstream and cause manifestations similar to allergies. According to the observations of specialists, it is pseudo-allergy that is more common than true allergy. This reaction is detected in almost 70% of people (i.e., the vast majority have suffered such an illness at least once in their lives), and true allergies are found in no more than 1-10% of people of different ages.

Why does pseudoallergy develop?

Pseudo-allergy often develops when eating a large amount of histamine-releasing foods.

A pseudoallergic reaction is formed in cases where the body enters large number substances that provoke its launch. The more there are, the stronger manifestations. For example, after eating a handful of raspberries, no reaction occurs, but after eating a double dose, a rash appears on the body.

The development of a pseudoallergic reaction is provoked by three main factors:

histamine metabolism disorders;
violation of fatty acid metabolism;
inappropriate activation of complement.

Most often, manifestations of a pseudoallergic reaction are provoked by improper histamine metabolism during, excessive consumption eating histamine-containing foods, decreased histaminopexia or increased histamine liberation.

The active release of histamine is caused by the action on mast cells of so-called liberating substances, contained in large quantities in foods such as chocolate, nuts, citrus fruits, strawberries, seafood, eggs, canned foods, etc. In addition, intense histamine production can be caused by certain physical and chemical factors: action medicines, alkalis, acids, insolation or vibration.

Pseudoallergy is often observed in chronically occurring organ ailments. digestive tract, symptoms of which are acidity disorders and damage to the mucous membrane of the stomach and intestines. These factors contribute to easier access of liberators to mast cells located in the gastrointestinal tract, and histamine and other mediators that provoke inflammatory reactions are produced in excess.

Pseudoallergy can result from so-called reduced histaminopexy. This process is observed with dysbacteriosis, prolonged use of certain medications, intoxication and is accompanied by a violation of histamine inactivation.

Often pseudo-allergy is provoked by eating foods with elevated levels of tyramine and histamine:

different types of cheese;
chocolate;
semi-finished products;
sausages, ham and sausages;
canned fish and meat;
herring;
pickled cucumbers and tomatoes;
cocoa beans;
brewer's yeast, etc.

Also, pseudoallergic attacks can be caused by various food additives (dyes, flavors, thickeners, etc.). Such substances include:

sodium nitrite;
tartazine;
monosodium glutamate;
sulfides;
benzoates;
salicylates;
benzoic acid, etc.

Others common reasons pseudo-allergies can occur in those products that contain increased amount pesticides, heavy metals, nitrites, nitrates, microorganisms and toxins.

Medicines involved in the development of pseudoallergic reactions:

antibiotics;
X-ray contrast agents;
plasma replacement agents, etc.

In rarer clinical cases pseudoallergy is caused by improper activation of complement, which occurs in a number of immunodeficiency conditions (for example, with hereditary angioedema), or taking non-steroidal anti-inflammatory drugs that disrupt the metabolism of arachidonic acid.

How does pseudoallergy manifest?

The symptoms of pseudoallergy are similar to those of allergies. It often manifests itself as urticarial rashes similar to urticaria.

The symptoms of this pathology are in many ways similar to a true allergic reaction - the patient’s local or systemic vascular permeability is disrupted (it increases), inflammation and swelling develop, blood cells are damaged and the muscle layer of internal organs spasms.

The nature and severity of symptoms are determined by the predominant damage to one or another organ or system. As a rule, most often the patient develops signs of rashes similar to urticaria and swelling in the area of the face and neck (). Often the patient has signs of disturbances in the functioning of the digestive tract, manifested by vomiting, etc. Often pseudoallergy is accompanied by symptoms of damage to the heart, blood vessels and respiratory system: arrhythmias, fainting due to hypotension, rhinitis, cough, and suffocation.

The nature of the symptoms of pseudoallergy depends on the root cause of the development of the pathological reaction.

For example, with a sharp release of histamine, its level in the blood increases sharply and vegetative-vascular reactions occur. In such cases, the patient experiences the following symptoms:

feeling of heat throughout the body;
redness of the skin;
migraine-like headaches;
loss of appetite;
difficulty breathing;
loose stool;
rumbling in the stomach;
nausea.

If the pseudo-allergy is provoked by disturbances in the metabolism of arachidonic acid, then the patient develops complaints similar to the manifestations of bronchial asthma:

dyspnea;
feeling of lack of air;
attacks of suffocation;
cough.

Sometimes pseudoallergy manifests itself as anaphylactoid reactions, the symptoms of which resemble. However, in such cases, the prognosis for the outcome of the emerging condition is more favorable. This fact is explained by the fact that with pseudoallergy such severe conditions are not accompanied by pronounced disturbances in the circulatory system and predominantly only one organ or system is affected.

Diagnostics

To suspect the presence of a pseudo-allergy is possible by carefully studying the patient’s complaints, his life history and conducting tests that make it possible to exclude the presence of a true allergy.

The distinctive criteria for pseudoallergy are the following facts:

the appearance of signs after the first contact with a liberator substance (for example, a rash occurs after eating chocolate, strawberries, oranges, etc.);
the occurrence of relapses after repeated contact with him or another liberator;
the presence of a relationship between the severity of symptoms and the amount of irritant substance entering the body;
locality of the pathological reaction;
pathological process limited to one organ or system (for example, the patient exhibits only a skin rash or only signs of digestive disorders).

To confirm the diagnosis of “pseudoallergy”, studies must be performed to exclude the presence of a true allergy:

– with pseudoallergy there is no eosinophilia characteristic of true allergy;
negative;
the level of immunoglobulin E remains within normal limits;
There are no specific immunoglobulins in the blood.

If the patient is examined in a specialized allergology department, then the following methods are used to differentiate pseudo-allergy from a true allergic reaction:

indomethacin test - performed with aspirin bronchial asthma;
administration of histamine at twelve duodenum– carried out in case of intolerance food products;
elimination-provocative tests, etc.

Treatment

Skin allergy tests for pseudoallergy are negative, that is, the allergen is not detected.

All patients with pseudo-allergies are advised to stop contact with the liberator substance, which is the cause of the disease. For example, for a patient with aspirin deficiency, it is enough to stop taking aspirin and other non-steroidal anti-inflammatory drugs; for a patient with rashes, it is enough to stop eating chocolate, foods with tartazine dye, etc. In addition, to eliminate the manifestations, it is recommended to take antihistamines, which are able to stop the effect of histamine on target cells.

If the development of a pseudoallergic reaction is provoked by excessive release of histamine, then the patient must limit the inclusion of daily diet those products that contain this component. Additionally, such patients are prescribed medications based on sodium cromoglycate in high dosages.
For pseudoallergy, which is accompanied by skin manifestations in the form, patients are prescribed the administration of histamine drugs in increasing dosages. Pseudoallergic hereditary angioedema is eliminated with a C1 inhibitor, testosterone preparations and infusion.
If pseudoallergy is accompanied by organ disorders or diseases gastrointestinal tract(, etc.), then treatment is supplemented by following a diet and taking medications that can regulate acidity and have an enveloping effect, protecting the mucous membranes of the intestines and stomach. If signs of dysbiosis are detected, the microflora is corrected using probiotics and reducing the amount of carbohydrates in the menu.
If the basis of a pseudo-allergic reaction is a disturbance in the metabolism of arachidonic acid, then you should stop taking non-steroidal anti-inflammatory drugs that alter the breakdown of this substance. Such patients should not take tablets that have cachets yellow and eat foods containing tartazine. Patients should follow an elimination diet with the exclusion or significant limitation of foods containing salicylates (citrus fruits, black currants, tomatoes, apples, cherries, etc.).

At severe course For pseudo-allergies, glucocorticosteroids are prescribed.

Forecast

The success of treating pseudoallergy depends on the severity of its manifestations and the root causes that caused the launch of such a pathology. In mild cases, the disease is quickly eliminated and is not accompanied by complications.

Allergies, as a fashion trend, are firmly entrenched in our lives, but not everyone suspects that they are suffering from allergies. Characteristic skin rashes, itching and other allergy symptoms may actually be the result of a false allergy.

After all, if you look at it, an allergy is immune reaction the human body to a stimulus, which produces antibodies, so-called immunoglobulins E, for specific proteins. Too much of these substances in the body can develop allergies.

Features of pseudoallergy

With a false allergy (pseudo-allergy), immunoglobulins E are not produced and antibodies are not involved, therefore, in order to identify the essence of the disease, you need to test for the presence of an allergen. Pseudo-allergy occurs under the influence of liberating substances that release histamine and provoke allergy symptoms and also require treatment. Also, with a false allergy, the symptoms are more pronounced if a large dose of the substance enters the body; with a true allergy, there is no such dependence.

The causes of allergic processes can be: stressful situations, as well as a reaction to drug intolerance of the body to some component. Food pseudo-allergy occurs due to non-acceptance of any product.

It could be like food additives, preservatives, everything you can’t do without food industry and many foods can cause the release of histamine from cells, these include: canned food, sausages, chocolate, nuts, eggs, cheese, fish and seafood, fruits and berries.

Often medications lead to the development of pseudo-allergy, since they contain a high content of chemicals that cause an allergic reaction.

Symptoms of a false allergy are often similar or close to the symptoms of an allergy. This may include redness of the skin, itching, fever, nausea and vomiting, hives, headache and dizziness, gastrointestinal colic, diarrhea and constipation, difficulty breathing.

And the more often a reaction to a specific allergen occurs, the more likely the disease will transition from pseudo-allergy to allergy. Processes developing under the influence of false allergies can be systemic, local or localized and are expressed in the form of urticaria, Quincke's edema, chronic rhinitis, bronchial, anaphylactoid shock. What pseudo-allergy looks like, the photo is presented below.

In the photo: Nasal congestion due to pseudoallergy

Pseudoallergy: treatment

Since each patient has his own individual case illness, the first step is to identify the specific allergen, limit its exposure and treat the symptoms. For recovery, you should follow a strict diet excluding allergenic foods and take antihistamines.

Pseudoallergy in children

Manifests itself in the form of skin lesions (atropic dermatitis), dysbacteriosis. The spread begins on the face, and only then spreads to the body. Treatment of such symptoms is similar to that of adults, that is, identifying the allergen and excluding or protecting the child from the allergen.

True and false allergies

The release of histamine is due to cellular damage triggered by physical factors such as cold. Not many people suspect that they suffer from such an allergy, while having chronic diseases such as rhinitis, chronic sinusitis, conjunctivitis, urticaria, radiculitis, migraine - the body's reaction to an irritant - cold.

How a reaction to cold air can be expressed in the form of sinusitis or a cold. Indoors, nasal congestion disappears, but outdoors it returns. The treatment for this symptom is to apply allergy drops to the nose 10–15 minutes before expulsion.

If you have a long stay in the cold, rub your sinuses and do acupressure faces. And the most necessary thing is a warm room and a cup of tea. Urticaria is also a reaction to cold. It manifests itself in the form of extensive redness of the skin, itching and even blisters.

If the air outside is cold and damp, wet snow, fog during a thaw - unprotected areas of the body (face, popliteal area, hands and feet, inner surface hips).

A dry and warm room and warm clothing will help get rid of the symptoms. You also need to take antihistamines and stay warm. To prevent a repeat reaction, you need to dress appropriately in such weather.

Clothing must be windproof and waterproof. Also, make sure that there are fewer synthetic and woolen items in your wardrobe, as they increase the manifestation of allergies; clothing should be cotton or linen.

If in the autumn-winter period, in sunny weather, tears flow from the eyes, the eyes itch, hurt, and upon entering the room, they immediately dry out and as if nothing had happened - these are obvious symptoms of pseudo-allergic conjunctivitis. You should not rub your eyes, as you may cause an infection, which will lead to true conjunctivitis. It is better to use handkerchiefs made of unscented paper.

Help prevent eye symptoms from allergies and sunglasses in sunny or snowy weather. Apply drops before going outside. It is also advisable, if possible, to avoid makeup and contact lenses.

Another manifestation of a false allergy (pseudo-allergy) is the bronchospastic reflex, which causes a sharp narrowing of the airways. The result is a sore throat, coughing and shortness of breath. In warmth, such symptoms quickly disappear.

To prevent the development of symptoms in the cold, you should cover your nose and mouth to warm the air a little and breathe only through your mouth. You can also use an inhaler to dilate the bronchi before going outside.

Migraine can also be caused by a false allergy, especially if you do not wear hats during the cold season. If you suffer from migraines every time you go out into the cold, then it’s better not to take risks and buy a warm hat, otherwise you can get much sicker serious illness, such as trigeminal neuralgia.

Many may have already encountered false allergies. However, what kind of disease is this? Typical allergic reactions and pseudoallergy symptoms can be very similar in appearance. But the nature of the two different diseases is completely different. False allergies have causes that do not include allergens. In other words, pseudoallergy is devoid of an immunological phase.

In a true allergic reaction, the allergen substance and immunoglobulin E are exposed. In the process of such interaction, biologically produced active substances, which lead to an allergic reaction.

Basically, the body’s pseudo-allergic response manifests itself when eating or dosage forms intolerance. And this type of allergic reaction is more common than ordinary allergies.

Almost 70% of the adult population and 50% of children suffer from this disease. Typically the body reacts this way as a result of the release of histamine. The factors leading to this release are different. Liberator substances included in the composition of products can also act: canned food, chocolate, eggs, fish, sausage, seafood, fruits, berries, nuts, baked goods with yeast.

A false allergy can develop only when the body has received a sufficient portion of substances that cause such a reaction. A larger amount of ingested substances leads to a more pronounced allergic reaction. For example, for three days in a row a person ate one banana per day, and everything was fine; on the fourth day he ate two bananas - and the body reacted with a rash on the face. Or another situation: there is no reaction to half an orange, but an allergy begins to eat a whole orange.

Risk factors and symptoms of pseudoallergy

Distinctive feature pathological condition the presence of released histamine appears. When a person feels normal, histamine is present in a bound state. Various influences can serve as a stimulus for the release of this hormone. physical nature at the cellular level: temperature fluctuations, ultraviolet radiation and some others.

But still, the main factor in the development of pseudo-allergy are liberating substances. What are they? These include preservatives, dyes, and food additives. In this regard, you should pay close attention to what you purchase for preparing various dishes.

Liberator substances

preservatives: sulfides, benzoates (E211), ascorbic acid (E200);
flavor enhancers: monosodium glutamates (E621), calcium (E623), magnesium (E625);
food dyes: tetrazine (E102).

Many foods may contain heavy metals, nitrites, pesticides, toxins, etc. The body may also have an allergic response to them.

Manifestations of a pathological condition are very easy to notice. When the level of histamine in the blood increases, they come from the autonomic and vascular system. Outwardly they look like hives on skin, areas of redness. There are severe pain head, feeling of heat and itching, difficulty breathing.

Dizziness is a constant companion of false allergies. Some patients experience vomiting, constipation and diarrhea, and anorexia. Even treatment for such manifestations is not so effective and the disease can reappear. In the future, hypertensive and hypotensive crises may appear.

Treatment methods for pseudoallergy

Before starting treatment, the doctor is obliged to find out the truth of the development of food allergies and eliminate the situation with intolerance to the product, since preventive measures will differ. The difference is that food allergies lead to disturbances in the immune system. A false allergy causes gastrointestinal disorders and disorders endocrine system. In case of allergies, the reaction can last a long time, and in case of food intolerance, it disappears after treatment.

How do doctors accurately diagnose pseudoallergy? The severity of the body's reaction is determined by the quantitative content of acquired histamines. Most accurate diagnosis is established through a blood test to detect immunoglobulin E. Its level will be high if the reaction is true, but if it is false, it will remain within the normal range.

To eliminate similar pathology a person should be attentive to his diet. In addition to the balance of the food taken, it should exclude allergen content. Therefore, the primary task of treatment is to find a dangerous food product.

Treatment is carried out with antihistamines. Needs to be eliminated somatic illness, which caused the pseudo-reaction to occur. Also, the doctor’s recommendations regarding treatment include measures to normalize intestinal microflora, that is, sulfur preparations, pancreatic enzymes and cellulose are prescribed.

If you manage to sound the alarm in a timely manner, then you can expect recovery soon.

Following a diet is also very conducive to this.

The prefix “pseudo” comes from the Greek word for “false.” Pseudo-allergy (para-allergy, false allergy) is diagnosed much more often than true allergy. It accounts for up to 70% of all negative reactions to allergen irritants. Processes occur that are very similar to a real disease, but in reality they are not one. Most often, the problem appears when eating certain foods or taking medications.

General information about pseudoallergy

For appearance allergic signs The histamine compound is responsible. Histamine synthesis begins when the body comes into contact with an allergen irritant. Human immunity is provided by immunoglobulin proteins (antibodies). They bind to molecules that produce antibodies (antigens). A massive release of antibodies is defined as an “immune response.” When, as a result of the ligament, histamine is synthesized and a reaction occurs, the antigens begin to be classified as allergens. But it happens that the antibodies did not form a bond with the irritants, and the release of histamine still occurred. This is called pseudo-allergy.

With paraallergies, you can observe the same external signs as with true allergies, but allergic inflammatory processes are not present. Pseudo-allergy often develops as a result of chronic diseases of the intestines, stomach, impaired metabolism of fatty acids, liver diseases, malfunction of the pancreas, prolonged drug therapy, various intoxications.

Except extremely rare cases failure of histamine metabolism, the synthesis of histamine in excessive amounts is provoked by liberators. This is the name given to substances, foods, etc. that enhance (release) the release of this hormone.

Liberators

The most common liberators among products:

chocolate;
red fish, red caviar, seafood;
nuts;
strawberry;
eggs;
citrus;
red meat;
soft cheese;
red wine;
tomatoes;
canned food;
cow's milk;
wheat;
smoked meats

Here is the most main factor- quantity. For example, a person is not allergic to strawberries. If he enjoys a glass of berries, no negative reaction there won't be. But if he, as they say, “goes crazy” and eats a kilogram at once, a rash, indigestion, etc. may appear. The body simply does not have time to cope with excessive amounts of the liberator product. As a result, histamine is released and a false allergy appears. Similar phenomena can also occur if a person eats the same strawberries, albeit not in excessive amounts, but in increased quantities for several days in a row. In this case it's going fast accumulation of irritant.

Other liberators:

antibiotics;
analgesics;
ultraviolet rays;
radiopaque compounds;
too low or high temperature;
various chemicals;
nitrates, pesticides;
preservatives, artificial food colors, flavorings, flavorings.

Symptoms

Pseudoallergic reactions are very similar to true ones. However, the symptoms of a false allergy directly depend on the amount of the provoking substance and are usually localized in one of the body systems.

May be observed:

hyperemia (redness) of the skin and mucous membranes;
blisters, rash;
itching, peeling of the skin;
nasal congestion, runny nose;
lacrimation, swelling of the eyelids;
tissue swelling (small);
disruptions in the functions of the digestive system (nausea, diarrhea, vomiting);
headache.

Pseudoallergy in children most often manifests itself as a skin rash, diarrhea, and dysbacteriosis. The rash usually appears first on the face, then on the body. Headaches often begin, children become capricious and sleep poorly.

The difference between the symptoms of pseudoallergy and a real reaction:

There is no too rapid onset of the disease.
The symptoms are not so severe.
There are almost no cases of asphyxia (suffocation) or a sharp decrease in pressure.
There is no severe swelling.
More often there are disturbances in the gastrointestinal tract.
Headache occurs more often.

Diagnostics

Only a specialist can distinguish a false reaction from a true allergy, since the signs are almost identical. It is necessary to contact an allergist, therapist, or pediatrician (if the child is ill). Blood samples are taken from adults and children. The level of immunoglobulin E is checked - the most important indicator. With a pseudo-allergy it will be within the normal range, and with a true allergy it will be overestimated.

Allergy tests may also be performed. A tiny number of suspected allergens are injected into small scratches. In case of paraallergy, all skin tests will be negative, that is, no redness or swelling will occur in response to any irritant.

Treatment

Once delivered correct diagnosis, the doctor must determine what exactly started negative reaction. The patient (or his parents, when it comes to the baby) must remember what food he ate over the last 2-3 days, what medications he took, perhaps he was exposed to the Sun for too long, etc.

Diet

It will be necessary to exclude from the menu the food that caused the reaction. The ban on its use lasts at least three months. Then you can try eating a small portion of the product and see how the body reacts.

The diet is also optimized. Obviously harmful products (fast food, soda, canned food, smoked meats, etc.) are limited, as well as products with a high allergic index, which can act as a liberator. Need to eat more raw vegetables and fruits, dairy products, lean fish and meat, greens. It is advisable to boil, steam, or grill food.

At the same time, therapy is carried out aimed at treating chronic gastrointestinal pathologies and treating dysbiosis. A specialist can recommend enzymes for better digestion of food and products that protect the mucous membranes from irritating factors.

Drug therapy

Treatment of pseudoallergy is practically no different from the therapy recommended for the true form of the disease. It is necessary to remove the consequences of histamine release (itching, rash, hyperemia), remove toxins and adjust the body to normal operation.

The doctor may prescribe:

Antihistamines - Telfast, Aleron, Xyzal, Zyrtec, Erius, Loratadine, Cetrin, etc. Syrups and drops are usually prescribed to young children. Infants are prescribed drops for oral use - Fenistil, Zodak, Parlazin, Zyrtec. Tablets for children, taking into account the drug, are prescribed either from 6 or 12 years.
Remedies for itching and urticaria - Soventol, Fenistil-gel, Beloderm, Psilo-balm, Lorinden, etc.
Vasoconstrictor drugs that remove swelling of the mucous membranes - Naphthyzin, Irifrin, Vizin, Nazol, Metazon, etc.
Drugs that reduce inflammation of the mucous membranes - Cromohexal, Allergokrom, Kronasol, etc.
Sorbents that help quickly remove toxins from the body - Laktofiltrum, Polysorb, Carbosorb, Enterosgel, for small patients - Smecta.

Traditional methods

They must be combined with traditional therapy. Consultation with a specialist is advisable, since there is a risk that folk remedies can also cause allergies.

Pour 200 g of large oat flakes into 1 liter of boiling water and leave for 8-10 hours. Strain and drink little by little all day. Course – 2-3 weeks.
Mix 100 g of glycerin or olive oil with 1 tsp. dry sage powder. Apply once a day to areas of skin that are itchy and flaky.
Baths and compresses with a decoction of string, yarrow, chamomile, and mint help relieve itching and rashes.
1 tsp Steam chamomile flowers with a glass of boiling water and strain. Drink a third of a glass three times a day before meals.
2 tbsp. strings and 1 tbsp. hop cones pour 1 liter of boiling water, leave for 40 minutes. Use as a lotion for itching.

Prevention

You need to be careful about foods that can cause the release of histamine, and eat them in moderation. Often adults do not have the willpower to deny their child a few extra candies, and then they are forced to deal with allergy symptoms. In addition, you need to carefully read product labels, since there are products that do not seem to be provocateurs, but contain many preservatives and additives. If possible, it is advisable to take organic fruit and vegetable products grown without chemicals.

Para-allergies, unlike a real disease, can be completely avoided. Here a lot depends on the person himself. You just need to follow simple rules and take a closer look at your health.

Pseudoallergy(Greek pseudēs false + allergy; synonym paraallergy) is a pathological process similar in clinical manifestations to allergies, but does not have an immunological stage of development, while the next two stages are the release (formation) of mediators (pathochemical) and the stage clinical symptoms(pathophysiological) - with pseudoallergy and true allergy they coincide.

What is pseudoallergy?

Pseudoallergic processes include only those in the development of which the leading role is played by mediators inherent in the pathochemical stage of true allergic reactions. Therefore, many reactions that are clinically similar to them, but do not have allergy mediators in the pathochemical stage, are not included in this group. For example, lactase deficiency is clinically similar to an allergy, but the mechanism of development of diarrhea in it is associated with a violation of the breakdown of lactose, which undergoes fermentation to form acetic, lactic and other acids, which leads to a shift in the pH of the intestinal contents to the acidic side, the accumulation of water in the intestinal lumen and its irritation, increased peristalsis and diarrhea.

Pseudoallergic reactions most often occur with drug and food intolerance.
Many medications (non-narcotic analgesics, radiocontrast agents, plasma-substituting solutions, etc.) more often lead to the development of pseudo-allergies than allergies. The frequency of pseudoallergic reactions to drugs varies depending on the type of drug, route of administration and other conditions and, according to different authors, ranges from 0.01 to 30%. Even such an allergenic antibiotic as penicillin causes a significant number of pseudo-allergic reactions.

As for food intolerance, it is believed that for every case of food allergy there are approximately 8 cases of pseudo-allergy, and the cause of the latter can be either the food itself or numerous chemicals(dyes, preservatives, antioxidants, etc.) added to food products or accidentally introduced into them.
Most allergens can lead to the development of both allergic and pseudoallergic reactions. The difference lies in the frequency of occurrence of both for each specific allergen. Even atopic diseases, which are truly allergic, can sometimes develop according to the mechanism of pseudo-allergy, i.e. without the participation of the immune mechanism.

Causes of pseudoallergy:

There are three mechanisms in the causes of pseudoallergy; histamine, impaired activation of the complement system and a disorder of arachidonic acid metabolism. In each specific case of the development of a pseudoallergic reaction, one of these mechanisms plays a leading role. The essence of the histamine mechanism is that biological fluids the concentration of free histamine increases, which has a pathogenic effect through the H1 and H2 receptors of target cells.

Histamine receptors are present on various subpopulations of lymphocytes, mast cells (mast cells), basophils, endothelial cells of postcapillary venules, etc. End result The action of histamine is determined by the place of its formation, the number and ratio of H1 and H2 receptors on the surface of cells. In the lungs, histamine causes bronchial spasm, in the skin - dilation of venules and an increase in their permeability, which is manifested by hyperemia of the skin and the development of its edema, and with a systemic effect on the vascular system leads to hypotension. An increase in histamine concentration in pseudoallergy can occur in several ways.

Thus, the acting factors have a direct effect on mast cells or basophils and cause either their destruction, accompanied by the release of mediators, or, acting on these cells through the corresponding receptors, activate them and thereby cause the secretion of histamine and other mediators. In the first case, the active factors are designated as non-selective, or cytotoxic, in the second - as selective, or non-cytotoxic.

Often this difference in effect is associated with the concentration (dose) of the active factor: at large doses the factor can be non-selective, at low concentrations it can be selective. Of the physical factors, freezing, thawing, high temperature, ionizing radiation, in particular X-rays, and UV radiation have a cytotoxic effect.

Among chemical factors, detergents, strong alkalis and acids, and organic solvents have this effect. A selective effect is exerted by polymeric amines (for example, substance 48/80), certain antibiotics (polymyxin B), blood substitutes (dextrans), bee venom, X-ray contrast agents, waste products of worms, calcium ionophores, and from endogenously formed substances - cationic proteins of leukocytes, proteases (trypsin, chymotrypsin), some complement fragments (C4a, C3a, C5a). Many foods have a pronounced histamine-releasing effect, in particular fish, tomatoes, egg white, strawberries, wild strawberries, chocolate. These products, like many others, can cause not only pseudo-allergic reactions, they may include immune mechanism and thereby lead to the development of food allergies.

Another way to increase the concentration of histamine is to disrupt the mechanisms of its inactivation. There are several ways in the body to inactivate histamine: oxidation by diamine oxidase, methylation of the nitrogen in the ring, oxidation by monoamine oxidase or similar enzymes, methylation and acetylation of the amino group of the side chain, binding by blood plasma protein (histaminopexy) and glycoproteins.

The power of the inactivating mechanisms is so great that the introduction of 170-200 mg of histamine chloride (at a rate of up to 2.75 mg/kg) into the duodenum of a healthy adult through a probe causes after a few minutes only a slight sensation of flushing to the face, the level of histamine in the blood is practically does not increase. In individuals with an increased inactivating ability of histamine, the entry into the body of a much larger amount of it causes a pronounced clinical picture(head urticaria, diarrhea), which is accompanied by a significant increase in the concentration of histamine in the blood.

The third way to increase the concentration of histamine is nutritional, associated with eating foods that contain other amines in fairly significant quantities. Thus, fermented cheeses contain up to 130 mg of histamine per 100 g of product, salami-type sausages - 22.5 mg, other fermented products - up to 16 mg, canned food - 1-35 mg. Chocolate, Roquefort cheese, and canned fish contain significant amounts of tyramine. In addition, some types of intestinal dysbiosis, accompanied by the proliferation of intestinal microflora with decarboxylating activity, lead to increased formation of the corresponding amines (histamine, phenylethylamine, tyramine) from histidine, phenylalanine, and tyrosine.

The second mechanism of pseudoallergic reactions involves inappropriate enhancement of the classical or alternative pathway of complement activation, resulting in the formation of numerous peptides with anaphylatoxic activity. They cause the release of mediators from mast cells, basophilic platelets, neutrophils and lead to aggregation of leukocytes, increasing their adhesive properties, spasm smooth muscles and other effects, which creates a picture of an anaphylactic reaction up to severe shock (see. Anaphylactic shock).

Complement activation is caused by polyanions and especially strongly by complexes of polyanions with polycations. Thus, the heparin + protamine complex activates C1, the initial link of which is the binding of CIq. Polysaccharides and polyanions of a certain molecular weight are an active alternative pathway of the complement transformation cascade due to the binding of an inhibitor of the third component.

Proteases cause pronounced activation of complement. Thus, plasmin and trypsin activate CIS, C3 and factor B, kallikrein cleaves C3 to form C3b. Complement can be fixed to aggregated gamma globulin molecules and, as a result, be activated. Aggregation of protein molecules in the body is observed in cryopathies. Outside the body, this occurs during long-term storage of pasteurized plasma, solutions of human serum albumin, gamma globulin, especially placental. Intravenous administration Such drugs can cause pronounced activation of complement and lead to the development of pseudo-allergy.

X-ray contrast agents, in addition to their effect on mast cells and basophils, can activate complement. This is due to damage to vascular endothelial cells, which leads to the activation of Hageman factor with the subsequent formation of plasmin, which already activates C1. At the same time, the kallikrein-kinin system is activated. Dextrans can also activate complement. Similar processes are possible during hemodialysis.

The most striking picture of pseudoallergy is observed with a deficiency of the inhibitor of the first complement component - C1 inhibitor. Normally, its concentration in blood plasma is 18.0±5 mg%. C1 inhibitor deficiency is associated with a gene mutation (frequency about 1:100,000) and autosomal dominant inheritance, which manifests itself in heterozygotes for this defect. In most cases, deficiency of this inhibitor is associated with a violation of its synthesis in the liver, which leads to a sharp decrease in the concentration of C1 inhibitor in plasma.

However, in a number of cases, there is a lack of activity of the inhibitor at its normal level, when the inhibitor is structurally changed, or even when elevated level inhibitor complexed with albumin. Inhibitor deficiency, as well as its reduced activity, lead to the development of a pseudo-allergic form of Quincke's edema. Under the influence of various damaging influences (for example, tooth extraction), physical activity, emotional stress Hageman factor (blood coagulation factor XII) is activated.

The activated factor turns on the plasmin system with the formation of plasmin from plasminogen, which, in turn, triggers the initial link of the classical pathway of complement activation, starting with C1. Activation goes up to C3 and stops here, because C3 has its own inhibitor. However, on initial stage a kinin-like fragment is formed from C2, which causes an increase in vascular permeability and the development of edema.

The third mechanism for the development of pseudoallergy is associated with a violation of the metabolism of unsaturated fatty acids and, first of all, arachidonic acid. The latter is released from phospholipids (phosphoglycerides) of the cell membranes of neutrophils, macrophages, mast cells, platelets, etc. under the influence of external stimuli (damage by drugs, endotoxin, etc.). The molecular process of release is quite complex and involves at least two pathways.

Both of them begin with the activation of methyltransferase and end with the accumulation of calcium in the cytoplasm of cells, where it activates phospholipase A2, which cleaves arachidonic acid from phosphoglycerides. The released arachidonic acid is metabolized by the cycloxygenase and lipoxygenase pathways. In the first metabolic pathway, cyclic endoperoxides are first formed, which then turn into classical prostaglandins of groups E2, E2a and D2 (PGE2, PGF2a and PGD2, prostacyclin and thromboxanes. In the second pathway, monohydroperoxyfatty acids are formed under the influence of lipoxygenases.

The products formed by the action of 5-lipoxygenase have been well studied. First, 5-hydroperoxy-eicosatetraenoic acid is formed, which can be converted to the unstable epoxide leukotriene A4 (LTA4). The latter can undergo further transformations in two directions. One direction is enzymatic hydrolysis to leukotriene B4 (LTV4), the other is the addition of glutathione to form leukotriene C4 (LTS4). Subsequent deaminations convert LTS4 to LTD4 and LTE4.

Previously, when the chemical structure of these substances was not known, they were designated as “slow active substance anaphylaxis." The resulting metabolic products of arachidonic acid have a pronounced biological effect on the function of cells, tissues, organs and systems of the body, and also participate in numerous feedback mechanisms, inhibiting or enhancing the formation of both mediators of their own group and mediators of other origin. Eicosanoids are involved in the development of edema, inflammation, bronchospasm, etc.

It is believed that disorders of arachidonic acid metabolism are most clearly manifested in intolerance to non-narcotic analgesics. From this group of drugs greatest number reactions associated with taking acetylsalicylic acid. Usually, along with acetylsalicylic acid, patients are sensitive to other analgesics - derivatives of pyrazolone, para-aminophenol, non-steroidal anti-inflammatory drugs of various chemical groups.

It is believed that analgesics inhibit the activity of cycloxygenase and shift the balance towards the preferential formation of leukotrienes. However, there are other mechanisms of intolerance. Thus, some patients are simultaneously sensitive to tartrazine, which does not alter the formation of prostaglandins.

Cromolyn sodium (Intal), which blocks the release of mediators from mast cells, can also block reactions to acetylsalicylic acid, although it does not inhibit the biosynthesis of prostaglandins. Therefore, it has been suggested that mast cells may be target cells for analgesics. This is also confirmed by the fact that in patients the reaction to an analgesic is often accompanied by an increase in the content of histamine in the blood plasma and its excretion in the urine. The possibility of complement participation in reactions to analgesics has not yet been proven. Considerable attention is paid to elucidating the possibility of including immunological mechanisms in the implementation of the pathogenic effect of these drugs.

However, this assumption did not find convincing confirmation and the idea was formed that intolerance to acetylsalicylic acid and other analgesics refers to pseudo-allergy. Denial of possibility immunological mechanism, and primarily IgE-mediated, is based, according to a number of authors, on the following observations: 1) the majority of patients with acetylsalicylic acid intolerance do not have atopy, and they do not experience immediate skin reactions to either this drug or its conjugates; 2) sensitivity to the drug is not transmitted passively by blood serum; 3) in patients with hypersensitivity to acetylsalicylic acid, it is also observed to other chemically different analgesics.

Symptoms of pseudoallergy:

The symptoms of pseudoallergic diseases are similar or very close to the clinical picture of allergic diseases. It is based on the development of such pathological processes as increased vascular permeability, swelling, inflammation, spasm smooth muscle, destruction of blood cells. These processes can be local, organ and systemic. They manifest themselves in the form of year-round rhinitis, urticaria, Quincke's edema, periodic headaches, dysfunction of the gastrointestinal tract (flatulence, rumbling, abdominal pain, nausea, vomiting, diarrhea), bronchial asthma, serum sickness, anaphylactoid shock, as well as selective defeats individual organs(gastritis, enteritis, myocarditis, etc.).

Sometimes there is a combination of allergic and pseudoallergic mechanisms of disease development. This is most clearly manifested in the development of bronchial asthma, combined with intolerance to acetylsalicylic acid and other analgesics and called aspirin bronchial asthma. Its the most expressed form manifested by asthma itself, nasal polyposis and hypersensitivity to acetylsalicylic acid and is referred to as the aspirin, or asthmatic, triad.

The combination of asthma with increased sensitivity to acetylsalicylic acid is detected, according to many authors, in 10-20% of patients with atonic or infectious-infective forms of bronchial asthma; Isolated aspirin asthma occurs in no more than 3% of cases. It is important that: 1) hypersensitivity to acetylsalicylic acid is an acquired condition and persists without taking drugs of this group; 2) these drugs cause the development of pathological processes in the upper and (or) lower respiratory tract; 3) some patients may experience symptoms affecting only the nose and (or) eye area at one time and the full asthmatic classic triad at another.

Diagnosis of pseudoallergy:

Taking into account the fact that the symptoms of allergic and pseudoallergic diseases often coincide, and the approaches to their treatment differ, there is a need to differentiate them. Sometimes a conclusion about the pseudo-allergic nature of the reaction is made on the basis of knowledge of the properties of the allergen causing the reaction. For example, it is known that analgesics disrupt the metabolism of arachidonic acid, and radiocontrast agents directly cause the release of histamine from basophils and mast cells.

More often, it is necessary to use the entire arsenal of specific allergological diagnostic methods. Their negative results, together with medical history and clinical data, allow us to draw a conclusion about the non-immunological nature of the disease. In table Table 1 shows some general differential diagnostic signs of allergic and pseudoallergic reactions, and table. 2 - differential diagnosis two forms of Quincke's edema.

Depending on the nature of the disease and the body system involved in the pathological process, special diagnostic methods carried out in specialized institutions. For food intolerance, use a test with the introduction of duodenum histamine. For urticaria, determining the fluorescence of lymphocytes with a 3-methoxy-benzanthrone probe, an elimination test, and determining total bilirubin in blood serum against the background of an elimination test.

In case of anaphylactoid reactions to medication, a test is performed to determine the release of histamine from blood leukocytes after adding the test drug to them in vitro. In bronchial asthma, the addition of indomethacin in vitro to a suspension of blood leukocytes leads to the production of leukotrienes and hyperproduction of PGE2a with a high PGF2a / PGE2 ratio only in patients with aspirin-induced asthma.

Treatment of pseudoallergy:

Treatment of patients in the acute period is etiotropic and pathogenetic. The etiotropic focus of treatment is to prevent, stop and eliminate, as far as possible, the action of the factor that caused the disease. In case of drug pseudoallergy, stopping the drug is effective. If you are intolerant to acetylsalicylic acid, it is not recommended to use pyrazolone derivatives, non-steroidal anti-inflammatory drugs, food coloring tartrazine and all yellow wafers, since they contain tartrazine. In case of food pseudo-allergy, it is necessary to identify the causative foods or additives to them and exclude them from the diet.

Pathogenetic therapy is aimed at blocking the pathochemical stage of development of pseudoallergy. With the histamine mechanism, treatment is based on the conditions leading to an increase in histamine concentration. However, in all cases of an increase in its concentration, antihistamines are indicated that block the effect of histamine on target cells. If this increase is associated with food intake, then correction is carried out diet, limiting or eliminating foods that have a histamine-releasing effect or contain it and other amines in large quantities.

Avoid products that cause irritation and recommend oatmeal, congee etc. or medications that have an enveloping effect. Limit excess consumption of carbohydrates if they lead to activation of intestinal microflora with decarboxylating activity. One of the most important reasons development of pseudo-allergy is dysbacteriosis. Therefore, in all cases of dysbiosis, its correction is necessary. Histamine release promoted by foods may be blocked by mouth cromolyn sodium in a large dose - 0.15-0.2 g 1 hour before meals.

In cases of decreased activity of histamine inactivation mechanisms, long-term subcutaneous administration of histamine solution in increasing doses is recommended. This method of treatment is especially effective in the pseudoallergic form. chronic urticaria. The complementary mechanism of P.'s development is usually accompanied by activation of proteolytic systems. Therefore, the use of proteolysis inhibitors is pathogenetically justified.

Treatment of pseudoallergic angioedema, which is based on a deficiency of the C1 inhibitor, includes the administration of the C1 inhibitor directly or fresh plasma and fresh frozen plasma containing it, and the plasmin inhibitor epsilon-aminocaproic acid, and then testosterone preparations that stimulate the synthesis of the C1 inhibitor. The main thing in the treatment of patients with impaired metabolism of arachidonic acid is to prevent the entry into the body of acetylsalicylic acid and, as a rule, the entire group of non-narcotic analgesics that change its metabolism.

At the same time, avoid eating yellow wafers and products containing tartrazine. It is necessary to recommend patients an elimination diet with the exclusion of products containing salicylates as preservatives or in their natural form (citrus fruits, apples, peaches, apricots, black currants, cherries, gooseberries, tomatoes, potatoes, cucumbers, etc.). Since it is difficult to exclude many of these vegetables, fruits and berries from the diet, and taking into account the fact that sensitivity to salicylates in different patients is very different, we can recommend not a complete exclusion, but a limitation of one degree or another of the use of these products.

Increased sensitivity to salicylates is also accompanied by increased histamine release. Therefore in acute condition Antihistamines and cromolyn sodium can be prescribed. For asthma patients, cromolyn sodium is prescribed by injection, and for food pseudo-allergy - orally. In severe cases, patients are given corticosteroids, which inhibit phospholipase activity and thereby block the release of arachidonic acid.

The prescription of calcium antagonists is also pathogenetically justified, since activation of phospholipase A2 occurs due to an increase in the content of free calcium in the cells. Patients with aspirin-induced asthma are given a course of hyposensitization with increasing doses of acetylsalicylic acid. In case clinical manifestations pseudo-allergies (pathophysiological stage, appropriate symptomatic treatment is prescribed.

Forecast:

The prognosis is determined by the nature of the pathogenetic mechanisms of pseudoallergy and the severity of the resulting disorders. It is favorable in mild cases when excluding factors causing development pseudo-allergies, dangerous in the development of anaphylactoid shock. In case of food pseudo-allergy, which develops against the background of a disease of the digestive system, the prognosis is determined by the success of treatment of the underlying disease.

Prevention:

Prevention comes down to eliminating factors that cause the development of pseudo-allergy. Polypharmacy should be avoided when treating a patient. Before prescribing a drug, it is necessary to ask the patient about tolerance of this medicine and groups of related drugs. If a pseudo-allergy is suspected, it is usually replaced provocative drug to a drug from another group.

Before the administration of radiocontrast agents, it is recommended to prescribe antihistamines, and patients who have a history of reactions to these drugs are prescribed a prophylactic short-term course of treatment with corticosteroids. Prevention of food pseudoallergy comes down to selecting an appropriate elimination diet and treating the underlying disease of the digestive system.