Induction of Immune Tolerance to Dietary Antigens.

The intestinal immune system is continuously exposed to massive amounts of diverse antigens derived from both food and intestinal microbes. Immunological tolerance to these enteric antigens is critical for ensuring intestinal and systemic immune homeostasis. Oral tolerance is a specific type of peripheral tolerance induced by the exposure of antigen via the oral route, emphasizing the role of intestinal immune system for preventing unnecessary hypersensitivity reactions to innocuous dietary and microbial antigens. Here, we discuss how dietary antigens are recognized by intestinal immune systems and highlight the role of Foxp3(+) regulatory CD4(+) T cells (Tregs) in establishment of oral tolerance, the tolerogenic features of intestinal dendritic cells that induce development of Foxp3(+) Tregs, and the factors that promote development of the intestinal dendritic cells.