In vitro response to Corynebacterium parvum of human effusion lymphocytes isolated from patients with malignant and benign disease.

Non-adherent effusion cells (EC), mostly lymphocytes, were isolated from the pleural effusions of 8 patients with malignant and 7 patients with benign disease. Corynebacterium parvum (Cp) induced increased methyl-3H-thymidine (methyl-3H-TdR) incorporation in EC cultures, but the response was lower than that usually found with autologous or allogeneic normal human blood lymphocytes. Experiments with highly purified effusion lymphocytes indicated that the response to CP was influenced by the presence of adherent cells, probably macrophages. Normal human monocytes incubated in vitro with supernatants of unstimulated EC cultures expressed slightly increased ability to suppress methyl-3H-TdR-incorporation in a human tumour cell line. Supernatants of Cp-stimulated EC induced a further increase in monocyte-mediated cytostatic activity. Cell-free effusion fluid from 8 patients were largely inactive when tested for induction of monocyte-mediated cytostatic activity in the same system, and the effusion fluid reduced monocyte methyl-3H-TdR-incorporation in vitro. Thus, Cp seems to be able to induce DNA-synthesis and release of mononuclear phagocyte-activating lymphokines in human effusion lymphocytes.