Figure 3.

Proposed model of regulatory B-cell-mediated immunoregulation in mucosal homeostasis. Regulatory B cells from mucosal-associated lymphoid tissue induce the expansion of protective CD8⁺ T cells in the intestine by presenting antigenic peptides from enteric microbiota or self-stress responses in an immunogenic setting. These expanded CD8⁺ T cells are cytolytic and play a role of monitoring immune responses in the intestine by directly targeting and killing activated CD4⁺ T cells. If validated, this concept would establish mechanistic links between bacterial commensalism, featured intestinal mucosal immune system, and the biology of IBD susceptibility.