Allergies in children

Allergies in children develop according to the same mechanism as in adults, and the reasons for their occurrence are the same.

The beginning of the twentieth century was full of discoveries in various fields of science and technology. Medicine was not left aside. One day, an Austrian pediatrician made a unique observation, which showed that the same substances cause a violent reaction of the body in most people. Thus, a whole group called "allergens" appeared, and a term denoting the body's reaction to the action of allergens - allergy. The name of the pediatrician who gave rise to a whole medical field - allergology - is Clement von Pirquet.

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What causes allergies in children?

Scientists' opinions, to this day, have strong differences on issues concerning the true causes of allergies in general and in children in particular. There are several mechanisms for the development of allergic reactions that are associated with disorders in individual body systems. These include:

• immune disorders;
• imbalance of intestinal microflora;
• increased amount of allergens in the contact area.

Allergies in children are often associated with all three causes, which begin to act sequentially, or, in other words, one cause becomes a platform for the addition of another. Thus, an imbalance in the intestinal microflora leads to the development of dysbacteriosis, and it, in turn, strikes at the immune system. The immune system, weakening, is unable to cope with the influx of harmful chemical or biological allergens from the environment. The child is surrounded by pets, strong fragrances, including the parents' perfumes, which can also become the very root cause. Constant exposure to an unspecified allergen leads to painful manifestations. The intestines cannot cope with food allergens, and medicinal allergens destroy the already weak intestinal flora.

Thus, we get a vicious circle, which can only be broken by carefully identifying the allergen and gradually selecting the correct treatment methods.

Allergic disorders of varying severity (from skin reactions to anaphylactic shock) and localization (atopic dermatitis, conjunctivitis, rhinitis, bronchial asthma, etc.) develop as a result of contact with exogenous allergens - genetically alien substances. When they first enter the body, they cause sensitization (usually with hyperproduction of specific IgE antibodies that are fixed on mast cells). The majority of allergens are proteins (usually the molecular weight of allergens is 10,000 - 20,000), but they can also be haptens - low-molecular substances that become immunogenic only after forming a complex with tissue or plasma carrier proteins.

Main groups of exogenous allergens

1. Aeroallergens are allergens found in the air in significant quantities:
   • pollen allergens (trees, grasses, weeds);
   • house dust allergens (house dust allergen complex, house dust mite allergens, cockroach allergens);
   • fungal allergens (outdoor, indoor);
   • epithelium and other animal allergens.
2. Food allergens.
3. Drug allergens.
4. Allergens from stinging insect venom.
5. Industrial chemicals and biological substances.

A more detailed description of allergens is given in the sections on individual nosological forms of allergic diseases.

The classification of R. Gell and P. Coombs (RRA Gell and P G. H. Coombs) implies the division of allergic reactions into 4 types. It should be emphasized that such division into types of allergy is based on the predominant form of immune response. In reality, there is a close connection between them and often a combination.

The German school of immunologists suggests distinguishing type V allergy, in which antibodies to cellular receptors (e.g., hormones) have a stimulating or blocking effect on the function of these target cells. They also suggested separately considering type VI (or IIa), in which cytolysis, carried out with the participation of specific antibodies (not activating complement), is mediated through FcR of non-specific killer cells. This is the so-called ADCC - antibody-dependent cellular cytotoxicity, with the help of which the body frees itself from virus-infected cells and bacterial agents that do not die inside phagocytes (e.g., gram-negative cocci).

Pathogenesis of allergies in children

The allergic process goes through the following stages:

1. immunological: interaction of the antigen with homocytotropic antibodies of the IgE or IgG4 classes fixed on the mast cell (type I - immediate hypersensitivity reactions); a specific region of the antibody with the antigen of the target cell membrane (type II - cytotoxic damage); non-specific fixation of the CIC on a cell that has FcR and C3R (type III - immune complex diseases, vasculitis) or a specific T-cell receptor of the killer cell with the antigen of the target cell membrane (IV T and P - delayed-type hypersensitivity - DTH). Thus, cell involvement is a common feature of the allergic form of the immune response:
2. pathochemical - release and synthesis of chemical mediators of allergy;
3. pathophysiological - clinical manifestations.

"Early phase" of anaphylaxis. In the pathochemical stage, the stage of release and formation of primary and secondary mediators is distinguished.

The key mechanism of local and general manifestations of type I allergy is degranulation of mast cells with the release of preformed primary mediators transported and synthesized by this cell. Among the mediators, the first in time (already in the 3rd minute) to be released are histamine, platelet-activating factor (PAF), eosinophil chemotactic factor (ECF), and prostaglandin D.

Then, within half an hour, leukotrienes (slowly reacting substance of anaphylaxis - MPC-A), thromboxane A2, endoperoxides, and also active forms of kinins are released, activating factor XII of blood coagulation, i.e. the coagulation cascade. At the same time, a whole spectrum of enzymes, as well as cytokines, are released from mast cells. This is the so-called "early phase" of anaphylaxis.

The "late phase" is observed after 6-12 hours (only at high concentrations of antigens) and has a pronounced inflammatory component mediated by mediators of activated eosinophils, polymorphonuclear granulocytes, platelets and macrophages. In this phase, there is an increase in vascular permeability, migration of leukocytes along the surface of the endothelium ("rolling effect") due to their interaction with adhesion molecules, fixation of cells on the vascular endothelium at the site of the reaction and migration of cells into tissues. In this case, erythematous infiltrates are formed on the skin, and obstruction in the lungs is caused by changes in the bronchial mucosa.

The trigger for inflammation in type II (antibody-mediated cytotoxic) and type III (immune complex-mediated, Arthus type, "immune complex diseases") allergies is activation of the complement system. The components of the complement system, activated in these cases by the classical pathway, have a range of effects: chemotactic, anaphylatotoxic C3d, C1a (non-specific degranulation of mast cells), opsonizing C1b, activating the release of granules by neutrophils - C5a, cytolytic - "membrane attack complex" - C6, C7, C9. The morphological characteristics of complement deposits in reactions of types II and III are different.

Primary mediators of type IV allergy - lymphokines (cytokines) are released from specific T-lymphocytes and have the following effects: chemotactic, blast-transforming, as well as cytolytic and regulatory.

Secondary mediators of allergy of all types of allergic reactions are common. As stated above, these are mediators of inflammation, hemostasis, hematopoiesis: biologically active substances of blood leukocytes, platelets, endotheliocytes; cascade activated proteolytic systems of plasma (coagulation system, plasmin, kinin, complement), metabolites of arachidonic acid, active forms of oxygen, NO, proinflammatory cytokines, chemoattractants, growth factors, neuropeptides (such as substance P). It is necessary to remember that in the process of activation of cascade systems of plasma new biologically active substances C3a, C5a-anaphylatoxins are formed, causing direct degranulation of mast cell; bradykinin - vasoactive peptide, active proteases, increasing permeability of vascular wall, and many others.

Clinical manifestations of allergic diseases are an integrative result of the action of primary and secondary mediators with the predominance of individual groups of substances depending on the type of allergy. The neuroendocrine system takes part in the regulation of allergic inflammation through a system of transmitters, neuropeptides, and tissue hormones. Homeostatic control is carried out with the participation of the adrenergic, cholinergic, and non-adrenergic-non-cholinergic nervous system.

Allergens causing IgE-mediated allergic reactions are thymus-dependent, i.e. they require mandatory participation of T-helpers to induce an immune response. Type II helpers (Th2) via IL4 stimulate B-lymphocytes to synthesize specific IgE antibodies; via IL-3 they ensure maturation and involvement of mast cells in inflammation; via IL-4, -5 - eosinophils, and via colony-stimulating factor - macrophages. Thus, type II T-helpers, mast cells and eosinophils with the help of cytokines (IL-4, -5, -13) and membrane-bound molecules (gr39) with the participation of IgE antibodies create a network of mutually directed positive signals (vicious circle) that maintain allergic inflammation (type I allergy).

What is considered an allergen?

The list of substances capable of causing allergic reactions in the body is great. For ease of identification, study and elimination, it is customary to conditionally distinguish allergens by their nature, which can be:

• food;
• chemical;
• medicinal;
• biological.

The most common are dust allergens, including small mites, which are found in large quantities in layers of house dust, plant pollen, microorganisms and substances contained in the fur of pets, and food. In recent years, numerous cases have been identified where allergies in children developed in response to mold fungi. Mold patches, which form in household conditions in rooms with high humidity, on food products, are becoming one of the strongest allergens.

An allergen can be absolutely any substance, drug or food component, which at first glance seems completely harmless. As a rule, symptoms appear immediately after interaction with the cause of the allergy.

Type classification of allergies

The classification of allergy types originates from the classification of allergens into groups, depending on the nature of their origin. Let's consider the most common types of allergies, including:

• food;
• seasonal;
• cold;
• atopic dermatitis.

Food allergies in children

Allergies in children, especially infants, are directly related to the food that enters their body and the food that the mother eats. During errors in the diet that nursing women allow, the child often experiences rashes on the cheeks, diaper rash and redness in all large folds of the body: groin, popliteal, elbow folds, neck, armpits. Intestinal problems quickly join in. Frequent diarrhea, which is watery in nature, abdominal pain, accompanied by constant crying of the child and pulling the knees to the chest. If the necessary measures are taken, the redness on the cheeks can develop into small ulcers that merge, forming a solid crust, when the skin is stretched, small cracks appear on it, causing severe pain to the child. Diaper rash strongly "corrodes" the skin, also leading to the formation of open ulcers. All this is a reaction to a food allergen.

If the baby's diet consists entirely of mother's milk and, in this case, the first signs of an allergic reaction appear, you should immediately analyze those products that make up the mother's diet. It is best to exclude, for a short time, absolutely everything that can in any way be considered an allergen. Make up a diet so that its basis consists of porridge, low-fat chicken broths, cottage cheese, dried fruit compotes, vegetable oils (sunflower, olive, soy). It is better to drink only clean water. When switching to such a strict diet, allergies in children should go away within the first day. If the symptoms do not disappear, it should be assumed that there is a reaction to milk protein, which is the main component of any milk. In this case, you should seek help from specialists as soon as possible - a pediatrician or an allergist.

Allergies to milk formulas are more common than to mother's milk. When switching from one feeding method to another, allergies in children appear quite often. This is due to the fact that a new protein enters the body. In cases where an allergy to a certain type of formula is detected, you should not experiment and leave it in the child's diet, it is better to choose a milk formula from another company, and be sure to pay attention to the components included in its composition. It is very likely that the composition will contain a vitamin supplement, which is also an allergen. In any case, as soon as an allergic reaction to food appears, you should contact a pediatrician to choose the best option for eliminating the causes and all undesirable consequences associated with it.

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Seasonal Allergies in Children

When one season changes to another, many adults begin to experience allergic reactions to certain irritants. Seasonal allergies in children occur not only in the spring, when the flowering season begins, but also in the summer, when the first pollen forms, in the fall, when late grasses bloom, and even in the winter - the body can also respond to very low temperatures with allergic reactions. Allergies in children can also be considered seasonal manifestations. Therefore, special attention should be paid to the appearance of symptoms such as redness of the eyes and increased lacrimation, persistent runny nose, swelling of the mucous membranes, especially the larynx, redness of the skin with abundant rashes on them. If these symptoms appear from time to time, with relapses at a certain time of year, it is safe to assume that these are signs of seasonal allergies.

Seasonal allergies in children, which occur from spring to autumn, are also called "hay fever" because of its connection with the beginning of flowering of many grasses, which are subsequently used to make hay.

Cold allergy in children

Cold allergy in children begins in the same way as any other type: reddening of the skin with severe itching, the appearance of a rash and swelling in certain areas of the skin. Later, spasm of the respiratory tract joins in. As soon as the child is exposed to low temperatures, breathing immediately becomes difficult. This is a clear sign of an allergy to cold. It is very difficult to determine the exact diagnosis on your own and isolate the root cause at home. Bronchospasms can be the cause of not only an allergic reaction to low temperatures, but also be a sign of the onset of an acute inflammatory process. Consulting a doctor and constantly monitoring changes in symptoms in response to the measures taken is what needs to be done at the very beginning.

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Atopic dermatitis

You can often see, especially on products intended for children, but with packaging designed for adults, a photo of a toddler with bright red cheeks. The color of the cheeks in the photo is so bright that many adults find them touching and take them for a sign of the baby's good health. However, any specialist - a doctor will say that such hyperemia of the cheeks is not a sign of good health, but a symptom of a skin allergic reaction. Allergies in children, manifested repeatedly and turning into a chronic stage, are called atopic dermatitis. It is its manifestation that are red cheeks in babies, upon close examination of which you can see that the redness is not the only thing on the cheeks, they are completely covered with a rash.

Atopic dermatitis is called differently, often diagnosed as "diathesis", but this is a more general name for a number of allergic diseases, the main manifestation of which is a skin reaction. Allergies in children, proceeding according to the principle of atopic dermatitis, develop from infancy and can proceed until adolescence. There are four stages of atopic dermatitis, which follow one after another, in stages:

• infant (0 to 2 years);
• children (up to 13 years);
• teenage (13-15 years);
• adult (15-18 years old).

Each of these stages has its own differences and mechanism of progression. The fact that these stages occur gradually, following one another, does not mean at all that it is impossible to cure atopic dermatitis at each stage. A child's body can "outgrow" this disease at any stage, and it will stop recurring. To do this, you should take timely treatment and preventive measures and follow a strict diet and adhere to all the rules of personal hygiene, not deviate from all the recommendations of a pediatrician and allergist.

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Diathesis

Allergies in children, manifested in skin reactions, are usually called by one word in everyday life: "diathesis". In fact, diathesis is just a form of allergy, a certain predisposition of the child's body to respond to allergens. Diathesis is not only rashes on the skin and its redness, it is also diaper rash that occurs constantly, and seborrheic areas on the scalp, and many other symptoms. Diathesis only plays the role of a harbinger of the possible development of many diseases, for example:

• eczema;
• dermatitis of various etiologies;
• neurodermatitis;
• psoriasis.

Diathesis has a food origin, more often associated with violations in the mother's diet than in the errors of the baby's own diet. Abuse of certain types of products during pregnancy can with a high degree of probability guarantee the appearance of diathesis in the child after birth. The category of products at risk for diathesis includes eggs, nuts, honey and oranges. During pregnancy, you need to be more careful in consuming these products.

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Allergies in children: diagnostics

Allergies in children are, unfortunately, quite common. In recent years, more and more children have been suffering from this affliction. The reason for this is environmental errors in the environment and, as sad as it may be, the low level of health indicators of future parents.

It is quite easy to make a diagnosis based on symptoms, approximate reasons for their appearance and the nature of their course. To establish a predisposition to certain allergens, it is necessary to do special tests, the adequacy and necessity of which will be indicated by an allergist. It is imperative to start the fight against allergies with a visit to this doctor. Only he can prescribe the correct list of all really necessary tests. It often happens that parents independently make a choice in favor of certain allergy tests, many of which are completely unnecessary and not indicative for a child, due to insufficient age or do not reflect the essence of a given reason.

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Treatment of allergies in children

An allergist prescribes all necessary allergological tests, analyses and, based on the data obtained, the most adequate treatment is selected. Most often, it consists of the following areas:

• Blockade of the release of mediators from mast cells (membrane stabilization).
• Blockade of the synthesis of biologically active substances, active O2 radicals, cytokines, NO; inhibition of the entry of Ca into the cell and its accumulation in the cytoplasm due to increased synthesis of cAMP.
• Blockade of H1-histamine receptors.
• Effect on the functional activity of biogenic amine antagonists.
• Increased elimination of allergens from the intestines and through the kidneys.
• Specific immunotherapy (obsolete names: hyposensitization, desensitization).
• Maximum exclusion of the allergen's effect on the child's body;
• Taking antihistamines that relieve the symptoms of the allergy itself;
• Selection of a diet and strict adherence to it;
• Removal of associated symptoms and treatment of secondary diseases;
• General strengthening procedures and activities.

It is always necessary to remember that allergies in children are the body's defense against foreign elements. With an allergic reaction, the fragile child's body signals that it has received substances that it cannot cope with. Attentive parents pay attention to all the unexpectedly appearing red spots, rashes and irritations, and begin to sound the alarm, and quite rightly so. The sooner the cause of allergic reactions is eliminated, the faster the child's body will restore the impaired functions.

Allergies in children should be perceived, first of all, not as a dangerous disease, but as help from the child's body, which it provides to the surrounding adults in the search for and elimination of causes that are harmful to it.