Immunoglobulin A (IgA, saliva)

Why this test? 

Assessment of the immune system state

In what cases is it prescribed?

Recurrent infections. 

Autoimmune diseases. 

Allergic diseases.

Testing preparation

Saliva for research is collected in a special container. 

The time of saliva collection must be specified in advance with your doctor. 

There should be no blood in the saliva: do not conduct the examination during the active phase or exacerbation of oral cavity diseases, do not brush your teeth with a brush or dental floss before the examination, do not consume drinks or food at least 30 minutes before the testing. 

It is necessary to remove lipstick and lip balm before the testing. 

1-2 hours before taking saliva for research, the patient should be in a calm state, not smoke.

Test information 

The main type of immunoglobulins (antibodies) involved in local immunity. S IgA has an additional secretory component-S, which is synthesized by the epithelial cells of the mucous membranes and attaches to the Ig A molecule at the time of its passage through the epithelial cells. The S-component increases the resistance of the molecule to the action of proteolytic enzymes. S Ig A is contained in secretions (milk, saliva, lacrimal fluid, secretions of the intestinal and respiratory tracts, in bile, in vaginal secretions, amniotic fluid).

Protects mucous membranes from pathogenic microorganisms, potential allergens and autoantigens. By binding to antigens, it inhibits their adhesion to the surface of epithelial cells and prevents their penetration into the internal environment of the body. IgA deficiency leads to recurrent infections, autoimmune disorders, and allergies. 

The half-life of antibodies of this class is 4-5 days. One of the immunoglobulins that plays an important role in the health of the respiratory tract and the protection of the lungs from diseases is secretory immunoglobulin A (sIgA). It is a dimer consisting of two monomers covalently linked to the secretory component, which protects it from destruction. 

This immunoglobulin lives only 5 days. Therefore, for its constant replenishment in the body, differentiation of B-lymphocytes into plasma cells takes place every day, since it is they who synthesize sIgA. In this regard, the surrounding cells produce cytokines, which contribute to the transition of B-lymphocytes into plasma cells and the beginning of the synthesis of sIgA. Thus, sIgA is responsible for local protection, and its regulatory role in combination with local synthesis, transport, and secretion distinguishes mucosal immunity from systemic immunity. 

This immunoglobulin is not able to bind complement or cause its activation. However, it performs various protective functions by interacting with various receptors of the immune system, which protects the mucous surfaces of the body from the penetration of microorganisms into the tissues. sIgA can bind toxins and, together with lysozyme, exhibits bactericidal and antiviral activity. It acts as an agglutinator of microorganisms and a neutralizer of toxins, inhibiting the binding of viruses and bacteria to the surface of mucous membranes, and thus inhibiting replication.