Immunoglobulin A (IgA, serum)
Why this test?
To assess local humoral immunity.
For diagnosis of immunodeficiency states.
To diagnose the causes of relapses of bacterial, viral, fungal and parasitic infections.
For diagnosing the state of the immune system in autoimmune pathologies, blood diseases and neoplasms.
In what cases is it prescribed?
When examining children and adults prone to frequent recurrent respiratory, intestinal and/or urogenital infections.
When monitoring the treatment of IgA-type myeloma.
When examining patients with systemic connective tissue diseases (autoimmune pathology).
In a comprehensive study of the state of the immune system.
In neoplasms of hematopoietic and lymphoid tissues.
When monitoring patients with immunodeficiencies.
Class A immunoglobulins are glycoproteins that are synthesized mainly by plasma cells of mucous membranes in response to local exposure to an antigen. In the human body, IgA exists in two forms - serum and secretory. Their half-life is 6-7 days.
Secretory IgA has a dimeric structure and is resistant to the influence of enzymes due to its structural features. Secretory IgA is found in tears, sweat, saliva, milk and colostrum, bronchial secretions, and the gastrointestinal tract and protects mucous membranes from infectious agents. 80-90% of IgA circulating in the blood consist of the serum monomeric form of this Antibody class. IgA are included in the gamma-globulins and make up 10-15% of all blood immunoglobulins. Antibodies of the IgA class are an important factor in the local protection of mucous membranes. They bind to microorganisms and prevent their penetration from the outer surfaces into deep tissues, enhance the phagocytosis of antigens by activating complement via an alternative pathway. A sufficient level of IgA in the body prevents the development of IgE-dependent allergic reactions. IgA do not penetrate the placenta, but enter the child's body with mother's milk during feeding. Selective IgA deficiency is one of the most common immunodeficiencies in the population. Frequency - 1 case per 400-700 people.
This pathology is often asymptomatic. IgA deficiency can manifest as allergic diseases, recurrent respiratory or gastrointestinal infections, and is often associated with autoimmune pathology (diabetes mellitus, systemic lupus erythematosus, rheumatoid arthritis, pernicious anemia). IgA deficiency is sometimes combined with an insufficient level of IgG-2 and IgG-4, which leads to more pronounced clinical signs of immunodeficiency.