Immunogenicity of 2 murine B16 melanoma variants with high metastatic potential

The expression of tumor-associated transplantation antigens (TATA) by two metastatic variants, isolated from B16 melanoma in vivo, was examined. The first, YB16 melanoma (amelanotic), was selectioned after a successive s. c. transplantations of B16 melanoma cells on the coisogenic Yellow AY/a mutant mice of C57BL/6J mice. The second, MB16 melanoma, characterized by a variable pigmentation, was obtained from a s. c. transplantation of YB16 melanoma cells on C57BL/6J mice. The comparison of TATA expressed by the two variants and the B16 melanoma, made between different modes of inducing tumor-rejection activity, revealed that i) these two variants failed to induce an autologous antitumor response, ii) they were resistant to crossed immunization with an immunogenic preparations of B16 melanoma and iii) only MB16 melanoma preparations reduced significantly the tumoral incidence of B16 melanoma cells. These data leads us to suggest i) that the s. c. transplantation of B16 melanoma cells on Yellow AY/a mice resulted in the selection of nonimmunogenic, amelanotic and metastatic cell population of YB16 melanoma and ii) the existence of an epigenetic regulation of melanogenesis and expression of TATA in MB16 melanoma cells carried on C57BL/6J mice.