Structure and function of human effusion macrophages from patients with malignant and benign disease. 2. In vitro cytostatic and cytolytic effect on human tumour cell lines.

Human effusion macrophages isolated from the pleural or ascitic effusions of 14 patients with malignant or benign disease usually inhibited methyl-3H-thymidine incorporation in an adherent human tumour cell line (NHIK 3025) when the macrophages were challenged with target cells immediately after isolation. The cytostatic activity disappeared when the macrophages were cultured for 18 hours in vitro before target cell challenge. The presence of endotoxin (LPS) or Corynebacterium parvum (Cp) during the macrophage-target cell interaction induced a small enhancement of the macrophage-mediated cytostatic activity. Preincubation of macrophages with Cp or Cp-induced lymphokine supernatants for 2-18 hours before target cell challenge induced increased cytostatic activity in the macrophage cultures. Adherent (NHIK 3025) or non-adherent (K-562) human tumour cells prelabelled with methyl-3H-thymidine, when added to freshly isolated macrophages, were lysed in a slowly progressive manner. The cytolytic activity to K-562 cells was enhanced by increasing macrophage density in the cultures, and by incubating the macrophages for 2 hours with lymphokine supernatants before target cell challenge. Morphological observations indicated that K-562 cells adhered to macrophage membranes, with lysis proceeding extracellularily.