Beyond antibodies: Emerging roles of B cells in gastrointestinal inflammation and disease.

B cells play a crucial role in maintaining immune homeostasis at mucosal surfaces, including those of the gastrointestinal (GI) tract. Perturbed humoral immunity and antibody-mediated functions of B cells are well described in patients with chronic GI inflammatory diseases. However, our understanding of antibody-independent B cell functions such as antigen presentation, immunoregulatory cytokine production and tissue remodeling are more limited. Comprehensively defining the immunobiology of B cells beyond humoral immunity during GI inflammation will improve our ability to develop effective, targeted treatments that modulate B cell pro- versus anti-inflammatory activity in the clinical management of GI inflammatory diseases. In this review, we discuss the emerging roles of B cells using antibody-independent mechanisms to maintain intestinal homeostasis, and how this evolves to B cells becoming active players in immunopathology underlying GI inflammatory conditions and specific GI cancers.