Interferon-gamma modulates protein kinase C activity in murine peritoneal macrophages

The content of Ca2+-, phospholipid-dependent protein kinase activity (protein kinase C) in murine peritoneal macrophages treated with recombinant interferon-gamma (IFN-gamma) has been investigated. Protein kinase C activity was solubilized by nonionic detergent extraction of sonicated cells and separated by high performance liquid chromatography on a TSK 4000 SW gel filtration column. The enzyme eluted from the column in a molecular weight range of 60-80 X 10(3) and was identified by virtue of Ca2+ and phospholipid requirements. Macrophages treated with recombinant IFN-gamma exhibited a substantial increase in total protein kinase activity which could be accounted for entirely by increased protein kinase C activity. This activity was enhanced as much as 5-fold over that seen in untreated macrophages and was specific for IFN-gamma in that other agents known to signal changes in macrophage function had no effect. The time required for the elevation of kinase activity was identical to that required for induction of other functions by IFN-gamma in macrophages. These observations suggest that protein kinase C may be a focus of regulatory action in IFN-gamma-mediated macrophage activation.