Tumor progression in human malignant melanoma: five stages defined by their antigenic phenotypes.

The antigenic profile of melanocytic cells in the course of local and systemic tumor progression of human malignant melanoma was investigated by the reactivity of a panel of monoclonal antibodies (MAbs) in frozen sections of histologically defined melanocytic lesions. Specific antigenic phenotypes made it possible to distinguish 5 groups of lesions which could be ranked in relation to each other due to the sequential acquisition or loss of progression markers. On this basis, a scheme of antigenic changes which accompany the stepwise transformation of normal skin melanocytes into highly malignant metastatic melanoma cells is proposed. The steps of tumor progression identified solely by phenotyping with MAbs were in complete concordance with the concept of melanoma progression derived from histological, statistical and clinical analyses. Furthermore, our finding that the expression of gp89 as well as HLA-DR antigens can be induced by interferon-gamma in vitro provides evidence that immune interferon may play a role in the regulation of genes leading to phenotypic changes in progressing melanoma cells.