Intrathymic programming of effector fates in three molecularly distinct γδ T cell subtypes

γδ T cells function in the early phase of immune responses. Although innate γδ T cells have primarily been studied as one homogenous population, they can be functionally classified into effector subsets based on the production of signature cytokines, analogous to adaptive T helper subsets. Unlike adaptive T cells, however, γδ T effector function correlates with genomically encoded TCR chains, suggesting that clonal TCR selection is not the primary determinant of γδ effector differentiation. A high resolution transcriptome analysis of all emergent γδ thymocyte subsets segregated based on TCRγ/δ chain usage indicates the existence of three separate subtypes of γδ effectors in the thymus. The immature γδ subsets are distinguished by unique transcription factor modules that program effector function.