Genetic requirements for the development and differentiation of interleukin-17-producing γδ T cells.

Most effector T cells are generated in the periphery following an encounter with a foreign antigen and exposure to soluble and membrane-bound mediators. There are, however, some T cell subsets, such as γδ T cells and natural killer T cells, that acquire their effector potential in the thymus before their emigration to the periphery. This developmental preprogramming enables these cells to differentiate rapidly into cytokine-producing effectors during the host immune response. This review focuses on murine interleukin (IL)-17-producing γδ T (γδ-17) cells, which have been shown, through their early production of IL-17, to have a critical role in multiple infectious and autoimmune diseases. Specifically, we discuss what is currently known about the genetic requirements for their generation and compare it with what is known about that of the more extensively studied IL-17-producing helper T (Thl7) cells. Based on this comparison, we propose a model for murine γδ-17 development and differentiation.