IL2 and hepatocellular carcinoma: Peripheral blood and CD11c+ tumor-infiltrating myeloid cells express PD-1 in HCC in both humans and mice, which repressed IL-2 and IFN-γ as well as antigen-specific CD8 T cell proliferation under in vitro and in vivo settings, respectively; suggesting that immune surveillance against tumors is strongly regulated by PD-1 expression on DCs [49].