Typically, MDSCs impair anti-tumor immune responses by blocking the proliferation and antitumor activities of effector CD8+ T cells, multiple pathways involved in this process, including elevated expression of arginase 1 (Arg1), secreting immunosuppressive cytokines such as IL-10, inducible nitric oxide synthase (iNOS) and ROS production. The gene discussed is CD8A; the disease is neoplasm.