Antitumor activity of macrophages in lung cancer patients with special reference to location of macrophages.

Antitumor activity of macrophages from the peripheral blood, pleural cavity, and alveoli of 35 patients with primary lung cancer was examined. Cytostatic activities of peripheral blood monocytes and alveolar macrophages from either tumor-bearing or non-tumor-bearing segments declined in association with metastasis to regional lymph nodes, an increase in tumor size, and the development of pleural invasion. However, no such correlation could be observed between the cytostatic activity of pleural cavity macrophages and the degree of pleural invasion. The cytostatic activity of pleural cavity macrophages was found to be suppressed when the pleural invasion extended beyond the visceral pleura to the neighboring lobe or chest wall. On the other hand, the cytostatic activity of pleural cavity macrophages was markedly augmented when pleural invasion was limited to within the visceral pleura, although it was low in patients with no visceral pleural invasion. These results suggest that the pleural cavity is isolated from sites of systemic immunological response and that systemic immunological response does not strongly affect pleural cavity macrophages.