Monocyte dysfunction in human cancer

: General immunobiologic studies in cancer patients have stressed measurements of lymphocyte function and have commonly ignored the monocyte-macrophage system. A preliminary study of peripheral blood monocyte-macrophage function was undertaken in a group of 90 cancer patients (18 breast, 32 colon, 13 head and neck, 9 lung, and 18 melanoma) and 70 controls. Studies included enumeration of extractible monocytes (EM), quantitation of differentiation into macrophages (macrophage precursor test: MP), evaluation of antibody-dependent cellular cytotoxicity (ADCC), and spontaneous cellular cytotoxicity (SCC) as measured with human erythrocytes, and measurements of monocyte and serum lysozyme activity. Breast cancer patients had normal profiles. Colon cancer patients showed the most profound abnormalities with decreased EM and MP and increased ADCC and SCC. Patients with Stage I and Stage II melanoma had normal profiles, whereas those with advanced melanoma had significantly decreased MP. This defect was restored in two patients by BCG immunotherapy. Head and neck cancer and benign breast disease patients had decreased EM, whereas patients with lung cancer had increased EM. Monocyte lysozyme production was unchanged in the cancer patients compared to controls. Serum lysozyme levels, however, were significantly increased in patients with cancers of the colon, head and neck, and lung. Although patients with localized breast cancer and melanoma had normal levels, these were increased in both patient groups with advanced disease. It would appear that the source of the increased serum lysozyme is probably not the peripheral blood monocytes, but could have originated in the intra-tumoral or tissue-bound macrophages which were not examined. Selected assays of peripheral blood monocyte function were deranged in certain types of cancer patients but were fully normal in others, and did not show consistent correlations with tumor type or stage. Tissue-bound or intra-tumoral macrophages might provide a more fruitful area for study in these disease categories.