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

gamma delta 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 gamma delta T cell antigen specificities, but instead determines their effector fate. When triggered through the T cell receptor, ligand-experienced cells make IFN gamma, whereas ligand-naive gamma delta T cells produce IL-17, a major initiator of inflammation. These advances warrant a fresh look at how gamma delta T cells may function in the immune system.