Gammadelta T cells play an essential role in several forms of tolerance.

Gammadelta T cells were discovered in the mid-1980s, but the antigens they recognize and the biological functions they mediate are poorly understood. Although gammadelta T cells have the capacity to augment immunity to certain infections and kill certain tumor cells, they are generally not required for development of antibody responses, for graft rejection, or for development of autoimmune diseases. Nevertheless, gammadelta T cells accumulate at sites of inflammation induced by infection, tumor growth, and autoimmune lesions, where they have been shown to reduce the inflammatory reaction and tissue damage. In this review, we summarize the evidence that gammadelta T cells play an important role in the induction of various forms of tolerance.