Role of intracellular calcium concentration and protein kinase C activation in IFN-gamma stimulation of U937 cells.
IFN-gamma enhances many monocyte functions, including oxidative metabolism and Ag presentation. IFN-gamma has been reported to increase the intracellular concentration of calcium ([Ca2+]i) and modulate protein kinase C activity in murine macrophages, but the signal transduction pathways induced by IFN-gamma in human cells and their functional significance are poorly understood. Our study examined the hypothesis that an increases in [Ca2+]i and protein kinase C activation are required for functional responses to IFN-gamma. The U937 cell line was used as a model of an IFN-gamma responsive cell. IFN-gamma caused a rapid and concentration-dependent increase in [Ca2+]i, which was partly inhibited by calcium-free medium, diltiazem, and TMB-8. IFN-gamma induced a fourfold increase in the concentration of inositol 1,4,5-trisphosphate. Induction of HLA-DR, Fc gamma R, CR3, and Mo3e Ag expression by IFN-gamma was blocked by concentrations of TMB-8 that inhibited an increase in [Ca2+]i, but not by protein kinase C inhibition by H-7 or inhibition of calmodulin with W-7. Ionomycin did not enhance Ag expression and PMA induced the expression of only the Mo3e Ag. We conclude that IFN-gamma induces antigenic expression on human U937 cells by a mechanism dependent on, but not limited to, an increase in intracellular calcium, which is likely due to inositol 1,4,5-trisphosphate generation.
Klein
J B
JB
Department of Medicine, University of Louisville School of Medicine, KY.
Schepers
T M
TM
Dean
W L
WL
Sonnenfeld
G
G
McLeish
K R
KR
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000943:Antigens, Differentiation / Q000378:metabolism; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism; D000954:Antigens, Surface / Q000378:metabolism*; D001692:Biological Transport; D002118:Calcium / Q000502:physiology*; D002451:Cell Compartmentation; D002460:Cell Line; D004789:Enzyme Activation; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D006684:HLA-DR Antigens / Q000378:metabolism; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology*; D015759:Ionomycin / Q000494:pharmacology; D007546:Isoquinolines / Q000494:pharmacology; D016177:Macrophage-1 Antigen; D008264:Macrophages / Q000502:physiology*; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology*; D011951:Receptors, Complement / Q000378:metabolism; D011961:Receptors, Fc / Q000378:metabolism; D017452:Receptors, IgG; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000943:Antigens, Differentiation; D015214:Antigens, Differentiation, Myelomonocytic; D000954:Antigens, Surface; D006684:HLA-DR Antigens; D007546:Isoquinolines; D016177:Macrophage-1 Antigen; D010879:Piperazines; D011951:Receptors, Complement; D011961:Receptors, Fc; D017452:Receptors, IgG; D015759:Ionomycin; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D007371:Interferon-gamma; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D015544:Inositol 1,4,5-Trisphosphate; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium