MDSCs accumulate in tumor and peripheral lymphoid organs in tumor-bearing hosts and impact effector cell function thru multiple mechanisms that include [74]—(i) inhibiting CD4+ and CD8+ T-cell proliferation and activation; (ii) altering macrophage to a type 2 phenotype; (iii) inhibiting the cytotoxicity of NK cells; and (iv) inducing Treg cells to escalate immunosuppression. This evidence concerns the gene CD8A and neoplasm.