Effect of protein kinase C inhibitor (H-7) and calmodulin antagonist (W-7) on pertussis toxin-induced IL-1 production by human adherent monocytes. Comparison with lipopolysaccharide as a stimulator of IL-1 production.

Abstract

Human adherent monocytes stimulated with 1 microgram/ml pertussis toxin (PT) produced interleukin-1 (IL-1), as measured by thymocyte co-stimulation assay and enzyme-linked immunosorbent assay (ELISA), specific for IL-1 alpha and IL-1 beta. To clarify the role of protein kinase C (PKC) and calmodulin in IL-1 production, we investigated the effects of a PKC inhibitor, H-7, and a calmodulin antagonist, W-7 on PT- and lipopolysaccharide (LPS)-induced IL-1 production by monocytes. Addition of 10 microM and 20 microM H-7 to the culture medium markedly suppressed both PT- and LPS-induced IL-1 production. PT-induced IL-1 production was significantly suppressed by 5 microM and 10 microM W-7. However, LPS-induced IL-1 production was not suppressed by W-7 at the concentrations tested. When monocytes were labelled with Quin 2/AM, IL-1 production by monocytes stimulated with PT and LPS was markedly suppressed. These results indicate that different pathways are involved in the IL-1 production by PT and LPS; both calmodulin- and PKC-dependent processes are necessary for the IL-1 production induced by PT, whereas LPS-induced IL-1 production is dependent on the PKC. Inhibition of IL-1 production by interfering with intracellular Ca2+ trafficking in Quin 2/AM-loaded monocytes may be associated with the inhibition of PKC and calmodulin activity.