Immunoglobulin A in the blood

Immunoglobulin A includes two types of specific proteins: serum and secretory. Immunoglobulin A in the blood serum is in the form of a monomer (90% IgA ₁ ), it is included in the fraction of β-globulins and accounts for up to 15% of Ig of blood serum. Secretory IgA is found in secrets (milk, saliva, tear fluid, secrets of the intestinal and respiratory tract) and exists only in the form of a dimer (IgA ₁ and IgA ₂ ). Antibodies of the class of immunoglobulins A are synthesized mainly by lymphocytes of the mucous membranes in response to local effects of antigens, protect the mucous membranes from pathogenic microorganisms, potential allergens and autoantigens. By binding to microorganisms, IgA AT inhibits their adhesion to the surface of the epithelial cells and prevents penetration into the internal environment of the organism, thus preventing the development of local inflammatory processes. Local synthesis of immunoglobulin A causes local immunity. Penetrating into the internal environment of the body, Immunoglobulin A inactivates bacteria and viruses, activates complement on an alternative pathway. The half-life of immunoglobulin A is 6-7 days.

In humans, serum immunoglobulin A is less than 50% of the total pool of this Ig.

Reference values of the content of immunoglobulin A in serum

Age	Concentration, g / l
Children:
1-3 months	0.06-0.58
4-6 months	0.1-0.96
7-12 months	0.36-1.65
2-3 years	0.45-1.35
4-5 years	0.52-2.2
6-7 years	0.65-2.4
10-11 years old	0.91-2.55
12-13 years old	1.08-3.25
Adults	0.9-4.5

[1], [2]