Role of cytokines, tyrosine kinase, and protein kinase C on production of superoxide and induction of scavenging enzymes in human leukocytes

We investigated the effects of proximal modulators of cytokines, tyrosine kinase (TK), and protein kinase C (PKC) on reactive oxygen species (ROS) generation and the induction of scavenging enzymes, superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px) of human neutrophils and lymphocytes, by using IL1-α, TNF-α, and IFN-γ and neutralizing antibodies to these cytokines. Inhibitors of TK (ST638 and herbimycin) or PKC (H-7, calphostin, and staurosporine) were also used. The results revealed that both O₂ generation stimulated by five different agents (opsonized zymosan, A23187, PAF, PMA, and fMLP) and the inductions of all three scavenging enzymes were potentiated by priming with TNF-α. In contrast, both O₂^- generation and enzyme induction were attenuated by priming with IL1-α, with the exception of PMA-stimulated O₂^- generation. IFN-γ decreased O₂^- generation but increased scavenging enzyme induction. Antibodies to all three cytokines and all the TK and PKC inhibitors decreased O₂^- stimulated by most agents, but markedly enhanced O₂^- levels stimulated by PAF. Induction of all three enzymes was enhanced equally by low concentrations of each of the three anticytokine antibodies, while each of the TK or PKC inhibitors decreased induction of SOD and GSH-Px and increased catalase induction. These results suggest that both ROS generation and scavenging enzyme induction are controlled in complex ways by the actions of these three proximal mediators. This supports our hypothesis that disturbances in the regulation of early events of cell activation can lead to oxidative tissue injury.