Dissociation between tumour cell cytostatic and immuno-suppressive capacity of human monocytes activated with lymphokines.

Activation of monocytes with lymphokines from BCG-stimulated lymphocytes increased the capacity to inhibit DNA-synthesis in a tumour cell line (NHIK 3025) at all stages of monocyte maturation in vitro. However, the capacity of monocytes to suppress DNA-synthesis in mixed lymphocyte cultures (MLC) was reduced, indicating a dissociation of the immuno-suppressive and tumour cell cytostatic functions of lymphokine-activated monocytes. Supernatants of lymphokine-activated monocytes inhibited DNA synthesis in the tumour cell line, but not in MLC. Monocytes from donors with a strong tuberculin reaction produced supernatants with a stronger cytostatic activity than monocytes from donors with a weak tuberculin reaction. By in vitro maturation, even the later monocytes acquired ability to produce supernatants that were strongly inhibitory to tumour cells.