PDCD1 and neoplasm: Secrete IL-10 and TGF-β to inhibits the activity of CD4+ T cells and B cells, reduce the release of inflammatory cytokines through the CTLA-4 and PD-1 pathways, directly induce target cells death via the Fas/Fasl and perforin/granzyme B pathways,thereby enhancing the anti-tumor effect [8]