Early steps in interferon-gamma production: possible involvement of Ca2+-calmodulin-dependent enzymes.
A23187 in combination with phorbol myristate acetate (PMA) strongly induces production of interferon-gamma (IFN-gamma) by human peripheral blood mononuclear cells (PBMC) and even by murine PBMC, which respond poorly to A23187 alone. Macrophage depletion of PBMC strongly reduces IFN-gamma production induced by several mitogens, but does not affect IFN-gamma production induced by A23187 and PMA. In addition the same stimuli are able in combination to induce strong amounts of IFN-gamma, even in the Jurkat T cell line. The protein kinase C inhibitor 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine (H-7) and the calmodulin antagonist N-(6-aminoehexyl)-5-chloro-1-naphthalenesulfonamide (W-7) were examined for their ability to inhibit IFN-gamma production induced by PMA and A23187. At concentrations near the Ki for protein kinase C, H-7 failed to inhibit PMA- and A23187-induced IFN-gamma production. In contrast, W-7 at low concentrations inhibited IFN-gamma production induced by the same stimuli. In addition OAG, which is known to directly activate protein kinase C, failed to act synergistically with A23187 in the induction of IFN-gamma. On the basis of these results we propose that A23187 and PMA may mimic the early steps of lymphocyte activation, without the requirement of macrophage, bypassing antigen-, or lectin-induced signal. Our results suggest that Ca2+-calmodulin-dependent reactions other than protein kinase C activation may be essential for IFN-gamma production, at least at level of the producing cells.
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002147:Calmodulin / Q000502:physiology*; D002478:Cells, Cultured; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis*; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D051379:Mice; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D002147:Calmodulin; D000001:Calcimycin; D007371:Interferon-gamma; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium