Chapter 16 – The Mucosal Immune System: Host–Bacteria Interaction and Regulation of Immunoglobulin A Synthesis

Adaptive coevolution of mammals and bacteria has led to the establishment of complex commensal communities on mucosal surfaces. Despite having available a wealth of immune sensing and effector mechanisms capable of triggering inflammation, the intestinal mucosa establishes an intimate dialogue with microbes to generate a state of hyporesponsiveness against commensals and active readiness against pathogens. A key component of this homeostatic balance is immunoglobulin A, a noninflammatory antibody isotype produced by mucosal B cells through class switching. Here we discuss the function of immunoglobulin A and the mechanisms by which intestinal B cells undergo immunoglobulin A diversification and production to establish a symbiotic relationship with commensal bacteria.