Macrophage antitumor activity: impaired responsiveness to interferon-gamma of macrophages from genetically defective mice.

Macrophages (M phi) from the genetically defective mouse strains C3H/HeJ, A/J and P/J were unable to develop high levels of antitumor activities when stimulated either with immune recombinant interferon gamma (IFN-gamma) or with nonimmune IFN-alpha and IFN-beta, as compared to M phi or normal C3H/HeN mice. IFN-gamma appeared to be an exceptionally good activator of C3H/HeN M phi, as it could induce tumoricidal capacities 3000 times more efficiently than nonimmune IFN. The high efficiency of IFN-gamma as M phi activator was indeed confirmed on defective M phi. In fact, at high doses IFN-gamma could also induce significant levels of both cytolytic and cytostatic activity in M phi of A/J and P/J mice, although it could not increase cytotoxic activities of C3H/HeJ M phi.