FcepsilonRI- and Fcgamma receptor-mediated production of reactive oxygen species by mast cells is lipoxygenase- and cyclooxygenase-dependent and NADPH oxidase-independent.
We investigated the enzymes responsible for FcepsilonRI-dependent production of reactive oxygen species (ROS) and the influence of ROS on mast cell secretory responses. 5-Lipoxygenase (5-LO) was the primary enzyme involved in ROS production by human mast cells (huMC) and mouse bone marrow-derived mast cells (mBMMC) following FcepsilonRI aggregation because incubation with 5-LO inhibitors (AA861, nordihydroguaiaretic acid, zileuton) but not a flavoenzyme inhibitor (diphenyleneiodonium) completely abrogated Ag-induced dichlorodihydrofluorescein (DCF) fluorescence. Furthermore, 5-LO-deficient mBMMC had greatly reduced FcepsilonRI-dependent DCF fluorescence compared with wild type mBMMC or those lacking a functional NADPH oxidase (i.e., gp91(phox)- or p47(phox)-deficient cells). A minor role for cyclooxygenase (COX)-1 in FcepsilonRI-dependent ROS production was demonstrated by inhibition of Ag-mediated DCF fluorescence by a COX-1 inhibitor (FR122047) and reduced DCF fluorescence in COX-1-deficient mBMMC. Complete abrogation of FcepsilonRI-dependent ROS production in mast cells had no effect on degranulation or cytokine secretion. In response to the NADPH oxidase-stimulating agents including PMA, mBMMC and huMC produced negligible ROS. IgG-coated latex beads did stimulate ROS production in huMC, and in this experiment 5-LO and COX again appeared to be the enzymatic sources of ROS. In contrast, IgG-coated latex bead-induced ROS production in human polymorphonuclear leukocytes occurred by the NADPH oxidase pathway. Thus mBMMC and huMC generate ROS by 5-LO and COX-1 in response to FcepsilonRI aggregation; huMC generate ROS upon exposure to IgG-coated latex beads by 5-LO and COX; and ROS appear to have no significant role in FcepsilonRI-dependent degranulation and cytokine production.
Swindle
Emily J
EJ
Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1881, USA. ejswindle@niaid.nih.gov
Coleman
John W
JW
DeLeo
Frank R
FR
Metcalfe
Dean D
DD
D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000172:deficiency / Q000276:immunology / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000166:cytology / Q000201:enzymology / Q000276:immunology; D015550:Cell Degranulation / Q000187:drug effects / Q000276:immunology; D002478:Cells, Cultured; D051545:Cyclooxygenase 1 / Q000172:deficiency / Q000276:immunology / Q000378:metabolism*; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007074:Immunoglobulin G / Q000494:pharmacology; D007152:Immunologic Capping / Q000187:drug effects / Q000276:immunology; D016859:Lipoxygenase Inhibitors; D008407:Mast Cells / Q000166:cytology / Q000201:enzymology* / Q000276:immunology; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism*; D009504:Neutrophils / Q000166:cytology / Q000201:enzymology / Q000276:immunology; D017382:Reactive Oxygen Species / Q000276:immunology / Q000378:metabolism*; D017455:Receptors, IgE / Q000276:immunology / Q000378:metabolism*; D017452:Receptors, IgG / Q000276:immunology / Q000378:metabolism*
D016207:Cytokines; D004791:Enzyme Inhibitors; D007074:Immunoglobulin G; D016859:Lipoxygenase Inhibitors; D008565:Membrane Proteins; D017382:Reactive Oxygen Species; D017455:Receptors, IgE; D017452:Receptors, IgG; D001094:Arachidonate 5-Lipoxygenase; D051545:Cyclooxygenase 1; C496512:Ptgs1 protein, mouse; D019255:NADPH Oxidases