On the road to tolerance--generation and migration of gut regulatory T cells.

The intestinal immune system potently supports the generation of induced Treg (iTreg) cells. Within intestinal lymphoid compartments iTreg cells receive homing cues, which direct these cells to the gut lamina propria where they expand and locally suppress immune responses. Yet iTreg cells are but one side of a coin, the other side of which comprises natural Treg (nTreg) cells generated in the thymus. nTreg cells, which act in concert with iTreg cells, also acquire a diversified pattern of homing receptors. Thus iTreg and nTreg cells can enter the gut, and draining lymph nodes to cooperatively ensure intestinal homeostasis.