CD8A and neoplasm: As a subset of effector T cells able to recognize tumor antigens and exhibit antitumor capability, tumor-reactive T cells have been found in several patient’s own tissues, such as tumor-infiltrating lymphocytes (TILs) in tumor lesions, PD-1+ lymphocytes in peripheral blood, CD8+ T cells in regional lymph nodes, and CD8+ T cells in the spleen [16,53–55].