Immunoglobulin A (IgA) is a type of antibody that plays a critical role in the immune function of mucous membranes. It is predominantly found in areas of the body such as the gastrointestinal tract, respiratory tract, and urogenital tract. IgA exists in two forms: serum IgA, which circulates in the blood, and secretory IgA, found in secretions like saliva, tears, and breast milk.
