Surface antigens of human melanoma cells defined by monoclonal antibodies. I. Biochemical characterization of two antigens found on cell lines and fresh tumors of diverse tissue origin.

Monoclonal antibodies were produced against melanoma cell lines derived from patients presently disease free. Based on tissue distribution of binding, the antibodies obtained could be used to classify melanoma surface antigens into groupings similar to those obtained from studies of autologous and xenogeneic antibodies. Three antibodies (21.43, 15.75 and 15.95) reacted with the immunizing tumor but not with peripheral blood lymphocytes or a lymphoblastoid cell line derived from the tumor donor. When tested on a broader cell panel, antibody 21.43 reacted only with melanoma lines, while antibodies 15.75 and 15.95 reacted with carcinoma cell lines as well as with the majority of melanoma cell lines. Antibody 15.95 precipitated a 49000 dalton glycoprotein from both melanoma and carcinoma cells. Antibody 15.75 precipitated a 74000 dalton glycoprotein from the surface of melanoma and carcinoma cell lines which is also found on freshly isolated tumor cells from melanoma and carcinoma metastases in vivo.