CD274 and neoplasm: Mechanisms exploited by tumor cells to inhibit CD8 T-cell-mediated immunity include the disruption of antigen presentation, downregulation of human leukocyte antigenmolecules, and induction of co-inhibitory molecules such as programmed death ligand (PD-L)-1 (B7 homolog 1 (B7-H1); CD274) and -2 (PD-L2; B7-DC; CD273).