Epithelial and mucosal gamma delta T cells.

Although they constitute a small part of the circulating lymphocyte population, gammadelta T cells are found in high abundance on mucosal and epithelial surfaces. These gammadelta T cells are activated in response to stress to the surrounding tissue and perform a number of functions depending upon the location and type of stress that has occurred. Roles elucidated recently for gammadelta T cells include modulation of epithelial homeostasis through insulin-like growth factor-1 and keratinocyte growth factor, lysis of cytomegalovirus-infected cells, and recruitment of inflammatory cells to sites of tissue damage. Recent advances have provided an understanding of the development of mucosal and skin gammadelta T cells and their roles in restoring and maintaining tissue integrity.