Total IgE in serum
With IgE( reactive), the mechanism of atopic allergic reactions is closely related. They have the ability to fast fixation on skin cells, mucous membranes, mast cells and basophils, therefore in free form IgE is present in blood plasma in negligible quantities. The half-life of IgE is 3 days in serum and 14 days on membranes of mast cells and basophils. Upon repeated contact with the Arg( allergen), the interaction of the reactive AT and Ar occurs on the surface of basophils and mast cells, which leads to degranulation, release of vasoactive factors( histamine, serotonin, heparin, etc.) and the development of clinical manifestations of anaphylaxis. IgE determines the type I immediate type of hypersensitivity - the most common type of allergic reactions. In addition to participating in allergic reactions of type I, IgE also participates in protective anthelmintic immunity. The reference values of the total IgE in the blood serum are given in the table.
Table Reference concentration values of total IgE in blood serum
Table Reference concentration values of total IgE in serum
Determination of total IgE in serum is used to diagnose atopic allergic diseases.).
Elevated concentrations of IgE are more often detected in children with allergies and sensitization to a large number of allergens. The incidence of elevated IgE levels is higher in patients with hypersensitivity to food and pollen allergens than in children with hypersensitivity to house dust and mold.
Table Major diseases and conditions accompanied by an increase in the concentration of total IgE in the blood serum
Table Major diseases and conditions accompanied by an increase in the concentration of total IgE in the blood serum
In adults, the determination of IgE concentration in serum is less diagnostic than in children. Elevated levels of IgE are detected only in 50% of patients with atopic bronchial asthma. The highest values of IgE concentration in the blood are noted when hypersensitivity to a large number of allergens in combination with bronchial asthma, atopic dermatitis and allergic rhinitis. When hypersensitivity to a single allergen, the concentration of IgE can be within normal limits.
Allergic bronchopulmonary aspergillosis is accompanied by a significant increase in IgE in the blood. Its concentration is increased in almost every patient with allergic aspergillosis in the period of acute pulmonary infiltration. The normal level of IgE in patients with active lung disease makes it possible to exclude the diagnosis of aspergillosis.
The definition of IgE is important for the diagnosis of a rare disease - hyper-IgE-syndrome. It is characterized by an increase in the concentration of IgE in the blood to 2000-50 000 kE / l, eosinophilia, pronounced urticaria and hyperemia on inhaled allergens, pollen, food, bacterial and fungal allergens. Bronchial asthma for this syndrome is uncharacteristic.
In Table.the ranges of total IgE in the blood serum( in adults) are given for some pathological conditions.
When assessing the results of the determination of total IgE, it should be borne in mind that approximately 30% of patients with atopic diseases have Ig concentration in normal.
A decrease in IgE in the blood is detected with ataxia-telangiectasia due to a defect in T cells.
Table Concentration of total IgE in serum in some pathological conditions [Totolyan AA, 1998]
Table Concentration of total IgE in serum in some pathological conditions [Totolyan AA, 1998]
When diagnosing an allergy, it is not sufficient to state a risethe concentration of total IgE in the blood. To search for a causative allergen, it is necessary to identify specific ATE class IgE.Currently, laboratories are able to detect allergen-specific IgE in serum to more than 600 allergens most often causing allergic reactions in humans. Nevertheless, the detection of an allergen-specific IgE( to some allergen or Ar) does not yet prove that this allergen is responsible for the clinical symptomatology. Interpretation of the results of studies should be carried out only after comparison with the clinical picture and the details of the detailed allergic-
histological history. The absence of specific IgE in the blood serum does not exclude the possibility of participation in the pathogenesis of the disease of the IgE-dependent mechanism, since local IgE synthesis and mast cell sensitization may occur in the absence of specific IgE in the blood( for example, in allergic rhinitis).AT of other classes, specific for this allergen, especially IgG, can cause false negative results.