A 3-TIERED VIEW OF THE ROLE OF IGA IN MUCOSAL DEFENSE

Mucosal IgA has generally been viewed as an immune barrier to prevent the adherence and absorption of antigens. Recent studies employing pol arized epithelial monolayers have suggested two additional functions f or mucosal IgA. One is to neutralize intracellular microbial pathogens , such as viruses, directly within epithelial cells. The second is to bind antigens in the mucosal lamina propria and excrete them through t he adjacent epithelium into the lumen, thereby ridding the body of loc ally formed immune complexes and decreasing their access to the system ic circulation.