Expression and modulation of a retrovirus-associated antigen by murine melanoma cells.

The antigen recognized by the monoclonal antibody MM2-9B6 is specific for melanomas originating in C57BL/6 mice. It is expressed by three melanomas of independent origin and not by normal or fetal tissues, by a wide variety of other nonmelanoma tumors in C57BL/6 mice, or even by melanomas syngeneic to other strains of mice. We have demonstrated that the expression of the relevant antigen is dependent on the replication and budding of a B-tropic ecotropic murine retrovirus. The relationship between the expression of this virus and carcinogenic progression may yield important insights into the cascade of events leading to neoplastic transformation.