Analysis of the roles of immune interferon (IFN-gamma) and colony-stimulating factor(s) in the induction of macrophage anti-toxoplasma activity.

Lymphokine-enriched, cell-free supernatants from specific antigen-stimulated spleen cells of toxoplasma-immune mice lacking detectable anti-toxoplasma antibody could generate effective anti-toxoplasma activity within normal (non-immune) murine peritoneal macrophages. Such supernatants also contained high levels of IFN-gamma as well as Ia-antigen(s) inducing activity. Supernatants from ConA stimulated normal (non-immune) spleen cells with high IFN-gamma, as well as CSF-containing supernatants from lung explants, lacked the capacity to induce anti-toxoplasma activity within peritoneal macrophages. ConA-stimulated spleen cell supernatants with high IFN-gamma titers but not CSF-enriched lung explant supernatants could induce the expression of macrophage cell surface Ia-antigen(s). Based on the results of our experiments, we have been able to eliminate the direct (by itself) role of IFN-gamma or CSF in generating macrophage anti-toxoplasma activity. However, the possibility that molecules like IFN-gamma or CSF synergize together with other immune spleen cell-derived factor(s) in the generation of effective macrophage anti-toxoplasma activity has not been ruled out.