Immunoglobulin E in the blood

The mechanism of atopic allergic reactions is closely connected with immunoglobulins E (reactants). They have the ability to fast fixation on skin cells, mucous membranes, mast cells and basophils, therefore in free form immunoglobulin E is present in blood plasma in negligible quantities. The half-life of immunoglobulin E is 3 days in the blood serum and 14 days on the membranes of mast cells and basophils. In case of repeated contact with the antigen (allergen), the interaction of reactive antibodies and antigens 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. Immunoglobulin E causes Type I hypersensitivity of immediate type - the most common type of allergic reactions. In addition to participating in allergic reactions of type I, immunoglobulin E also participates in protective anthelmintic immunity.

Reference values (norm) of the concentration of total immunoglobulin E in serum

Age	Concentration, kE / l
1-3 months	0-2
3-6 months	3-10
1 year	8-20
5 years	10-50
15 years	15-60
Adults	20-100

Increased concentration of immunoglobulin E is more often detected in children with allergies and sensitization to a large number of allergens. The frequency of detection of an increased level of immunoglobulin E is higher in patients with hypersensitivity to food and pollen allergens than in children with hypersensitivity to house dust and mold.

Major diseases and conditions, accompanied by an increase in the concentration of total immunoglobulin E in serum

Diseases and conditions	Possible reasons
Allergic diseases caused by IgE antibodies	Allergens:
Atopic diseases:
allergic rhinitis;	pollen;
atopic bronchial asthma;	dust;
atopic dermatitis;	food;
allergic gastroenteropathy	medicinal;
Anaphylactic Diseases:	chemical substances;
systemic anaphylaxis;	metals;
urticaria and angioedema	foreign protein
Allergic bronchopulmonary aspergillosis	Unknown
Helminthiases	IgE-AT
Hyper-IgE syndrome (Job's syndrome)	Defect of T-suppressors
Selective IgA deficiency	Defect of T-suppressors
Wiskott-Aldrich Syndrome	Unknown
Thymic aplasia (Syndrome Di-Georgie)	Unknown
IgE myeloma	B-cell neoplasia
The "graft versus host" reaction	Defect of T-suppressors

[3], [6], [7], [8]

Increase of immunoglobulin E

In adults, determining the concentration of immunoglobulin E in serum is less diagnostic than in children. Elevated levels of immunoglobulin E are detected only in 50% of patients with atopic bronchial asthma. The highest values of the concentration of immunoglobulin E 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 immunoglobulin E can be within the normal range.

Allergic bronchopulmonary aspergillosis is accompanied by a significant increase in the content of immunoglobulin E 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 immunoglobulin E in patients with active lung disease makes it possible to exclude the diagnosis of aspergillosis.

Determination of immunoglobulin E is important for the diagnosis of a rare disease - hyper-IgE-syndrome. It is characterized by an increase in the concentration of immunoglobulin E 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.

When evaluating the results of determining the total immunoglobulin E, it should be borne in mind that approximately 30% of patients with atopic diseases have a concentration of immunoglobulin E in normal.

When is immunoglobulin E downgraded?

Reduction of the content of immunoglobulin E in the blood is detected with ataxia-telangiectasia due to a defect of T cells.

The concentration of total immunoglobulin E in the blood serum under certain pathological conditions

Pathological conditions	Concentration, kE / l
Allergic rhinitis	120-1000
Atopic bronchial asthma	120-1200
Atopic dermatitis	80-14,000
Allergic bronchopulmonary aspergillosis:
Remission;	80-1000
Exacerbation	1000-8000
IgE-myeloma	15 000 and more

When diagnosing an allergy, it is not enough to ascertain the increase in the concentration of total immunoglobulin E in the blood. To search for a causative allergen, it is necessary to identify specific antibodies of the immunoglobulin E class. Currently, laboratories are able to determine the allergen-specific immunoglobulin E in serum to more than 600 allergens most often causing allergic reactions in humans. Nevertheless, the detection of an allergen-specific IgE (to any allergen or antigen) does not yet prove that it is this allergen that is responsible for the clinical symptomatology. Interpretation of the results of studies should be carried out only after comparison with the clinical picture and data of a detailed allergological anamnesis. The absence of specific immunoglobulin E in the blood serum does not exclude the possibility of participation in the pathogenesis of the disease of the IgE-dependent mechanism, since local synthesis of immunoglobulin E and sensitization of mast cells can occur even in the absence of specific immunoglobulins E in the blood (for example, in allergic rhinitis). Antibodies of other classes specific for this allergen, especially the class of immunoglobulin G, can cause false negative results.