PDCD1 and neoplasm: For instance, PD1 and TIM3 can differentially modulate the anti-tumor activity of specific subsets of murine γδ T cells, namely Vγ6+ and Vγ4+ cells, which produce IL-17A.550 In human, the exhaustion of intratumoral γδ T cells correlates with the expression of various immune checkpoints such as PD1, TIGIT, TIM3, CTLA4, and CD39.551,552 As for BTLA, it negatively regulates human Vδ2 T cell proliferation553 and curbs γδ T cell numbers and sustains normal frequencies of γδ T cell subsets.