[Relation between immunogenicity and differentiation of metastasis in an experimental murine melanoma]

The graft into the footpad of Jackson mice of B16 melanoma cells which are only slightly pigmented, induces the simultaneous appearance of achromatic and well-pigmented metastatics. We have analysed histologically both types of metastases from the 8th to the 20th day after the resection of the primary tumor. The percentages of mitoses are higher in the achromatic metastases than in the pigmented ones. Both are infiltrated by lymphocytes and by a small number of macrophages and polymorphonuclears. A statistical analysis demonstrates however that the percentage of lymphocytes is not related to the importance of the metastase pigmentation. The discussion is devoted to the relations between the infiltration by lymphocytes, the immunogenicity and the differentiation of the tumor.