Figure 2.

Parallel Regulatory Mechanisms for Induction of Mucosal Immunity and Tolerance

Intestinal ECs release immune regulatory factors, such as TSLP, RA, and TGF-β1, upon sensing antigens from the lumen. These immune mediators condition DCs to generate CD103⁺ DCs and TipDCs. Such regulatory DCs produce more immune regulatory factors, such as TGF-β1, RA, IL-10, and IL-27, which reinforce mucosal homeostasis and tolerance by promoting the development of IgA responses and regulatory T cell responses, including Treg and Tr1 responses. Treg and Tr1 cells suppress mucosal and systemic responses by T_h1 cells, T_h17 cells, and CTLs. Such a situation may represent a challenge for mucosal vaccines aimed at eliciting mucosal and systemic T cell-mediated immunity.