Implication of macrophage no and cytokine secretion in the cytotoxicity of transplantable melanomas as regards the progression of these tumors.

We studied the connection between the secretion of TNF-alpha, IL-6, OSM and NO by hamster peritoneal macrophages (animals bearing two forms of hamster transplantable melanomas of common origin but differing in growth rates, levels of differentiation and immunogenicity) and the cytotoxic effect of these macrophages on the cells of those two melanoma lines. The melanotic melanoma, the native form of melanoma, evoked an increase of cytokine secretion, especially of TNF-alpha, while the amelanotic melanoma line caused an increase of macrophage cytotoxic activity and of NO release. These observations seem to reveal that the biological features of transplantable melanomas and their progression influenced changes in the cytotoxic activity of peritoneal macrophages by changing the effector mechanism of this phenomenon.