Thymic maturation determines γδ T cell function, but not their antigen specificities

γδ T cells contribute uniquely to host immune defense, but how they do so remains unclear. Recent work suggests that thymic selection does little to constrain γδ T cell antigen specificities, but instead determines their effector fate. When triggered through the T cell receptor, ligand-experienced cells make IFNγ, whereas ligand-naïve γδ T cells produce IL-17, a major initiator of inflammation. These advances warrant a fresh look at how γδ T cells may function in the immune system.