Natural Killer Cells and Other Effector Cells, and Their Roles in Resistance against Cancer

Abstract

The role of the immune system in resistance against tumor growth has been the subject of intense interest during the last 10–15 years. To a large extent, attention was focused on this issue by the convincing documentation that some tumors in mice had tumor-associated antigens that could be recognized by the host and could thereby induce specific resistance against progressive tumor growth (Gross, 1943; Foley, 1953; Prehn and Main, 1957; Klein et al., 1960). In addition to such tumor-associated transplantation antigens, early workers in tumor immunology looked for and described tumor-specific antigens, i.e., antigens on tumor cells that appeared to be qualitatively different from those on normal cells. Such antigens were reported to be present on a variety of human tumors (for reviews see Herberman and Mclntire, 1979; Herberman, 1979) as well as on tumors of experimental animals. A further impetus to the field was provided by the development of in vitro assays for detecting humoral and cell-mediated immune responses to tumor-associated cell surface antigens. Considerable reactivity was detected in tumor-bearing or tumor-immune individuals, which was often assumed to be directed against the tumor-associated transplantation antigens (reviewed by Herberman, 1974, 1979). These findings led to extensive efforts at immunotherapy and immunodiagnosis of cancer, based on the expectation that these immunologic approaches would rapidly lead to major advances in the clinical management of patients with cancer.