The secretory immune system.

Several features distinguish mucosal from systemic immunity, depending on the anatomical and functional characteristics of the organs involved. Secretory IgA immunoglobulins are the main effectors of the mucosal immune system and their protective aspects are well documented. Serum IgA have received less attention but are equally important, since they control and remove in a non-phlogistic way antigens crossing the mucosal barriers.