Shared antigenic determinant expressed on various mammalian melanoma cells.

The interspecies cross-reactive melanoma antigen recognized by a syngeneic monoclonal anti-B16 melanoma antibody (M2590) was characterized. The melanoma antigen with cross-species determinants was detected in culture supernates or NP-40 extracts of all melanoma cell lines of mouse, hamster and human origins tested, but not in those of other tumors or normal tissues. Physicochemical analyses using gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that the melanoma antigen was a macromolecular complex composed of acidic sialoglycoproteins with a molecular weight of 31,000 daltons. Moreover, the antigens from mouse and human melanoma were shown to have the same molecular weights. The carbohydrate nature of the cross-species determinant was also investigated by treatment with exoglycosidases or pronase; the results suggested that the epitope is composed of carbohydrate side chains with terminal sialic acid.