Natural killer sensitivity of tumor cells isolated from primary and metastatic lesions of four Bomirski melanoma variants.

Natural killer (NK) sensitivity of melanoma cells isolated from primary and metastatic lesions of four Bomirski melanoma variants was compared. The hamster melanomas differed in their growth rate and metastatic pattern. We found that during tumor growth of all the variants tested, NK sensitivity of melanoma cells at the metastasis formation stage was significantly lower in both primary and metastatic tumors than in cells isolated from primary tumors at transplantation. In the case of Ma, Ab and Ab-455, NK sensitivity of primary tumor cells was higher than that of the cells isolated from metastatic deposits. These data obtained from a spontaneous metastasis tumor model argue for the role of NK cells in preventing metastatic spread of Bomirski melanomas studied.