PDCD1 and neoplasm: Several proinflammatory cytokines, including TNF-α, IL-β, IL-6, and IL-23, are produced by TAMs in the tumor stroma of HCC and induce the expansion of IL-17-producing CD4+ Th17 cells that suppress antitumor immunity by overexpressing PD-1, CTLA-4, and glucocorticoid-induced TNF receptor family-regulated protein (GITR) [72].