http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2906674/ Ligand recognition during thymic development and γδ T cell function specification Christina Meyer,a Xun Zeng,a,b and Yueh-hsiu Chiena, Abstract γδ T cells develop in the thymus before entering the periphery. Recent work suggests that thymic development does little to constrain γδ T cell antigen specificities, but instead determines their effector fate. When triggered through the T cell receptor, ligand-naïve γδ T cells produce IL-17, ligand-experienced cells make IFN-γ and those that are strongly self-reactive make IL-4. Importantly, γδ T cells are able to make cytokines immediately upon TCR engagement. These characteristics allow γδ 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 γδ T cells may function in the immune system.