Immunoglobulins (Igs) are proteins contributing to immunity mechanisms. Immunity is specific to the lymphoid system, which consists of organs (spleen, thymus, bone marrow) and cells (lymphocytes). Immunoglobulins are secreted by B lymphocytes in the blood, and in this way are exported for the specific functions of humoral immunity.
Immunoglobulin A (IgA) represents approximately 10-15% of serum Igs, but a large amount of IgA is found in secretions (saliva, tears, bronchial secretions, nasal mucosa, etc.). However, the exact role of serum IgAs is not yet clear.