Potentiation of tumor necrosis factor-alpha-mediated cytotoxicity of mast cells by their production of nitric oxide.
Nitric oxide (NO or endothelium-derived relaxing factor) has many of biologic actions, including the maintenance of blood pressure, inhibition of platelet aggregation, and cytotoxicity by phagocytic cells. Several cell types produce NO from L-arginine. Given recent emphasis on mast cell (MC)-dependent TNF-alpha-mediated cytotoxicity, we investigated the role of NO in rat peritoneal MC (PMC)-and intestinal mucosal mast cell-mediated cytotoxicity. MC cytotoxicity against the TNF alpha-sensitive target, WEHI-164, was potentiated by L-arginine. The NO competitive inhibitors, N omega-nitro-L-arginine and NG-methyl-L-arginine, diminished the cytotoxicity of rat PMC by 27 and 17%, respectively. However, hemoglobin, which binds to NO, inhibited the cytotoxic activity of PMC by 49% in the presence of 1 mM L-arginine and by 24% in L-arginine-free medium. The latter suggests that PMC use intracellular stores of L-arginine to produce NO. Neither hemoglobin nor NO metabolites affected human rTNF-alpha cytotoxicity. Furthermore, sodium nitroprusside, with its free radical NO group, restored PMC cytotoxicity in L-arginine-free medium to the level observed in 1 mM L-arginine medium. Studies with a platelet aggregation bioassay and various NO inhibitors confirmed that PMC produce NO. In addition, increased levels of NO2- were observed in medium of A23187, TNF-alpha, or WEHI-164-stimulated PMC.
Department of Microbiology and Infectious Diseases, University of Calgary, Alberta, Canada.
E Y
EY
Bissonnette
C M
CM
Hogaboam
J L
JL
Wallace
A D
AD
Befus
D000818:Animals; D001120:Arginine / Q000502:physiology; D003602:Cytotoxicity, Immunologic; D004357:Drug Synergism; D007111:Immunity, Cellular; D008407:Mast Cells / Q000502:physiology*; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D010974:Platelet Aggregation; D051381:Rats; D011919:Rats, Inbred Strains; D014409:Tumor Necrosis Factor-alpha / Q000633:toxicity*
D009566:Nitrates; D009573:Nitrites; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D001120:Arginine