Immunoglobulin E in the blood

The mechanism of atopic allergic reactions is closely related to immunoglobulins E (reagins). They have the ability to quickly fix on the cells of the skin, mucous membranes, mast cells and basophils, therefore, in free form, immunoglobulin E is present in the 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. Upon repeated contact with the antigen (allergen), the interaction of reagin 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 immediate hypersensitivity - the most common type of allergic reactions. In addition to participating in type I allergic reactions, immunoglobulin E also takes part in protective antihelminthic immunity.

Reference values (norm) of total immunoglobulin E concentration in blood 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

Elevated immunoglobulin E concentrations are more often detected in children with allergies and sensitization to a large number of allergens. The frequency of detection of elevated immunoglobulin E levels is higher in sick children with hypersensitivity to food and pollen allergens than in children with hypersensitivity to house dust and mold.

Main diseases and conditions accompanied by an increase in the concentration of total immunoglobulin E in the blood 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:	chemicals;
systemic anaphylaxis;	metals;
urticaria and angioedema	foreign protein
Allergic bronchopulmonary aspergillosis	Unknown
Helminthiasis	IgE-AT
Hyper-IgE syndrome (Job's syndrome)	T-suppressor defect
Selective IgA deficiency	T-suppressor defect
Wiskott-Aldrich syndrome	Unknown
Thymic aplasia (DiGeorge syndrome)	Unknown
IgE myeloma	B-cell neoplasia
Graft versus host disease	T-suppressor defect

[ 1 ], [ 2 ], [ 3 ], [ 4 ]

Increased immunoglobulin E

In adults, determination of the concentration of immunoglobulin E in the blood serum has less diagnostic value than in children. Elevated levels of immunoglobulin E are detected only in 50% of patients with atopic bronchial asthma. The highest values of immunoglobulin E concentration in the blood are noted in hypersensitivity to a large number of allergens in combination with bronchial asthma, atopic dermatitis and allergic rhinitis. In hypersensitivity to one allergen, the concentration of immunoglobulin E may 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 during the period of acute pulmonary infiltration. Normal levels of immunoglobulin E in patients with active lung disease allow us 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, severe urticaria and hyperemia to inhaled allergens, pollen, food, bacterial and fungal allergens. Bronchial asthma is not typical for this syndrome.

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

When is immunoglobulin E low?

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

Concentration of total immunoglobulin E in blood serum in some 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 above

When diagnosing an allergy, it is not enough to establish an increased concentration of total immunoglobulin E in the blood. To search for the causative allergen, it is necessary to detect specific antibodies of the immunoglobulin E class. Currently, laboratories are able to determine allergen-specific immunoglobulin E in the serum to more than 600 allergens that most often cause allergic reactions in humans. However, even the detection of allergen-specific IgE (to any allergen or antigen) does not prove that this allergen is responsible for the clinical symptoms. The interpretation of test results should be carried out only after comparing them with the clinical picture and detailed allergy history. The absence of specific immunoglobulin E in the blood serum does not exclude the possibility of the participation of an IgE-dependent mechanism in the pathogenesis of the disease, 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 to a given allergen, especially the immunoglobulin G class, may cause false negative results.