The role of epithelial cells in immune regulation in the gut

A variety of mechanisms contribute to the ability of the gut to either reac t or remain tolerant to antigens present in the intestinal lumen. Intestina l epithelial cells can control the uptake, transmission and presentation of luminal antigens through an astonishingly diverse set of pathways. Antigen s can moss the epithelial barrier via non-specific pinocytotic, specific re ceptor mediated or intracellular/paracellular bypass pathways. The differen tial processing and presentation by a variety of restriction elements may r esult in the activation of functionally distinct target cell populations wh ich have the capacity to regulate the predominant trend of immune unrespons iveness within the gut.