Secretory IgA (sIgA) is a predominant immunoglobulin found in mucosal secretions, playing a critical role in the immune defense of mucosal surfaces. It is a dimeric form of immunoglobulin A (IgA) that is combined with a secretory component, which protects it from enzymatic degradation. sIgA is crucial in maintaining the balance between protection and tolerance in the mucous membranes of the respiratory, gastrointestinal, and urogenital tracts.
