MODULATION BY MHC CLASS-I ANTIGENS OF THE BIOLOGY OF MELANOMA-CELLS -NONIMMUNOLOGICAL MECHANISMS

Many human as well as experimental tumours, including melanoma, expres s reduced levels of major histocompatibility complex (MHC) Class I ant igens. Decreased MHC Class I antigen expression may be selected during neoplastic progression because it allows tumour cells to escape killi ng by cytotoxic T lymphocytes. Furthermore, the regulatory role of MHC Class I antigens in the proliferation of T cells suggests that abnorm alities in MHC Class I antigen expression may play a role in the disor dered proliferation of malignant cells and in their metastatic potenti al by non-immunological mechanisms. This paper reviews some of the ava ilable evidence supporting the concept of non-immune functions of MHC Class I antigens in the biology of malignant cells, with emphasis on e xperimental models for metastatic melanoma.