DEMONSTRATION AND ISOLATION OF MURINE MELANOMA-ASSOCIATED ANTIGENIC SURFACE-PROTEINS

Melanomas are antigenic and induce the formation of antibodies in both syngeneic and xenogeneic species. The nature of melanoma-associated antigens remains problematic, however. We found that xenogeneic (goat) antiserum to the mouse (C57BL/6) B16 melanoma, following appropriate absorptions with nonmelanoma cells, showed specificity for melanoma-associated surface antigens of B16 and one other murine melanoma. The antibody to B16 did not react with histocompatibility antigens, mouse-specific xenoantigens, viral antigens or melanin. The IgG fraction of the goat antibody was cross-linked covalently to protein A-Sepharose using dimethylsuberimidate. This immunoadsorbent was used to isolate shed antigens from cultures in which B16 cells had been grown and from detergent extracts of biosynthetically labeled (3H-leucine) B16 cells. The immune-affinity purified antigen preparation contained two major components of apparent molecular weight 60,000 and 50,000 daltons as assessed by SDS-polyacrylamide gel electrophoresis. Immunization of rabbits with immune-affinity purified B16 antigens induced antibodies which bound specifically to B16 cells. © 1979.