Protective Activities of Mucosal Antibodies

Abstract Extensive studies of mucosal antibodies actively induced by immunization and infection or passively administered to nonimmunized subjects have convincingly demonstrated the essential role of antibodies in the prevention of mucosally acquired infections. Mucosal antibodies display their protective functions by several mechanisms, depending on their levels and antigen specificity in various external secretions; Ig isotype association, which differs in the intestinal versus genitourinary tract; molecular form, such as monomeric and polymeric Ig; and highly variable glycosylation patterns. The inhibition of antigen uptake, antibody and glycan-mediated interference with microbial attachment to epithelial cell receptors, intraluminal aggregation of bacteria, and the ability to neutralize biologically active antigens such as viruses and bacterial products represent the major protective mechanism of mucosal antibodies. The ability to induce antibodies of desired specificity and relevant effector functions in diverse external secretions, with a focus on the dominant secretory IgA isotype with its advantageous protective potential, is the most important goal in the generation of mucosal vaccines.