Role of tumor-associated macrophages in lung cancer.

The percentage of tumor-associated macrophages recovered (TAMR) and antitumoral activity of tumor-associated macrophages (TAM) were examined in 77 patients with resectable primary lung cancer. TAM was obtained by plastic adherence following trypsinization. TAMR increased from Stage I to Stage II and decreased in Stage III. It also increased in N1 as compared with N0 and N2 but was unrelated to tumor size. However, the cytostatic activity of TAM declined with advance in stage of the disease and an increase of tumor size, but it was relatively unaffected by the presence of metastasis to regional lymph nodes. There was no correlation between TAMR and the recurrence rate; however, cytostatic activity of TAM was correlated significantly with the prognosis of totally resected cases. TAMR and cytostatic activity of TAM tended to be lower in palliatively resected cases. These results suggest that the assessment of the antitumor activity of TAM, but not merely TAMR, may give prognostic information for lung cancer patients.