Ligand recognition during thymic development and gammadelta T cell function specification.

gammadelta T cells develop in the thymus before entering the periphery. Recent work suggests that thymic development does little to constrain gammadelta T cell antigen specificities, but instead determines their effector fate. When triggered through the T cell receptor, ligand-naïve gammadelta T cells produce IL-17, ligand-experienced cells make IFN-gamma and those that are strongly self-reactive make IL-4. Importantly, gammadelta T cells are able to make cytokines immediately upon TCR engagement. These characteristics allow gammadelta T cells to initiate an acute inflammatory response to pathogens and to host antigens revealed by injury. These advances warrant a fresh look at how gammadelta T cells may function in the immune system. 2010 Elsevier Ltd. All rights reserved.