PDCD1 and melanoma: Flow cytometry of SLNs and regional LNs of patients with melanoma revealed a rise in exhausted programmed cell death protein 1 (PD1)+ and T cell immunoglobulin and mucin domain-containing protein 3 (TIM3)+ CD8 T cells and CD127−CD25+ regulatory T (Treg) cells with increasing DCCDgp100 (P < 0.0001 for CD8 T cells and P = 0.0066 for Treg cells, Pearson’s correlation; Fig. 4f).