In vitro studies on the tumour cytotoxicity of normal, stimulated and immunologically activated mouse macrophages.

Peripheral macrophages (MO) from mice injected with proteose-peptone (P), thioglycollate (T) medium or BCG and from mice undergoing a graft versus host (GVH) reaction were tested for their cytotoxicity towards three murine tumour cell lines. The ability of lipopolysaccharide (LPS) and lymphokines to increase cytotoxicity was also studied. TMO were only slightly cytotoxic and this cytotoxicity was not enhanced by LPS and lymphokines. PMO showed the same degree of cytotoxicity as TMO, but this could be enhanced by LPS and lymphokines. Resident macrophages (RMO) sometimes resembled TMO and sometimes PMO. BCGMO were highly cytotoxic and could not be further activated by LPS and lymphokines. GVHMO were moderately cytotoxic but could not be further activated by LPS and lymphokines in contrast to the MO from hybrid controls.