IgA antibodies are produced by plasma cells located in the mucosal linings of the body. These plasma cells reside mainly in the lamina propria, a layer of loose connective tissue found beneath the epithelium in mucosal linings. Once produced, IgA can exist in two forms: serum IgA and secretory IgA (sIgA). The latter is transported across the mucosal epithelium to the luminal side, where it serves as the first line of defense against pathogens.
