Earlier, we have found a depletion of effector NK cells in syngeneic B16 tumor bearing Cd47−/− mice, which was associated with elevated B16 tumor growth in these mice.29 Previous studies treating immunocompetent and T cell-deficient mice bearing immunogenic syngeneic tumors with a CD47-blocking antibody or antisense morpholino combined with tumor irradiation observed tumor regression only in immunocompetent mice but not when CD8+ T cells were depleted.19,21 These data indicate that an CD8+ T-cell response is required for the antitumor activity of therapeutic CD47 blockade. This evidence concerns the gene CD8A and neoplasm.