The macrophage content of tumors is unrelated to levels of NK cell-mediated resistance.

Three malignant tumors (3LL carcinoma, mFS6 sarcoma, and B16 F1 melanoma) were transplanted in mice with congenital (beige) or acquired (anti-asialo GM1-treated) defects of natural killer cell (NK) activity. The macrophage content of the neoplastic tissues was not influenced by host NK activity levels. These data suggest that NK cell-mediated resistance does not play an appreciable role in the regulation of the levels of tumor-associated macrophages in established malignancy.