Immune regulation in the intestine: a balancing act between effector and regulatory T cell responses.

The immune system in the intestine must respond rapidly to invading pathogens without mounting sustained effector cell responses to the indigenous commensal bacteria. Results from this laboratory using the T cell transfer model of colitis suggest that specialized populations of regulatory T cells control the immune response in the intestine. Regulatory T (Tr) cell activity is enriched within the naturally arising CD4(+) CD25(+) Tr subset that has been shown to prevent a number of inflammatory diseases. CD4(+) CD25(+) Tr cells control intestinal inflammation induced by both innate and adaptive immune responses via IL-10- and TGF-beta-dependent mechanisms. Recent results have shown that CD4(+) CD25(+) Tr cells can cure established colitis, suggesting their utility for the treatment of inflammatory bowel disease.