Superoxide Generation In Human Neutrophils Research Articles

A novel conformationally restricted protein kinase C inhibitor, Ro 31-8425, inhibits human neutrophil superoxide generation by soluble, particulate and post-receptor stimuli

A novel, bis-indolylmaleimide, Ro 31-8425, bearing a conformationally restricted side chain, inhibits protein kinase C isolated from rat brain and human neutrophils with a high degree of selectivity over cAMP-dependent kinase and Ca 2−/calmodulin-dependent kinase. It also inhibits phorbol ester-induced intracellular events known to be mediated by protein kinase C(p47 phosphorylation in intact platelets, CD3 and CD4 down-regulation in T-cells). Ro 31-8425 inhibited superoxide generation in human neutrophils activated by both receptor stimuli (formyl-methionyl-leucylphenylalanine, opsonized zymosan. IgG and heat aggregated IgG) and post-rcceptor stimuli (1,2-dioctanoylglycerol and fluoride). The compound also blocked antigen driven, but not IL-2 induced, T-cell proliferation. These results support a central role for protein kinase C in the activation of the respiratory burst and antigen-driven T-cell proliferation.

Endothelin-1 enhances superoxide generation of human neutrophils stimulated by the chemotactic peptide n-formyl-methionyl-leucyl-phenylalanine

Endothelin-1 (ET-1) by itself was not an effective stimulus for inducing the superoxide (O2-) generation of human neutrophils, but it enhanced the O2- generation stimulated by the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP) about 2-fold when the cells had been preincubated with ET-1 for 10 min at 37 degrees C. The concentration at which ET-1 was 50% effective was 1 x 10(-10) M, and the maximal effect was obtained at 1 x 10(-8) M. The enhancement was observed over the range of the effective concentrations of FMLP (10(-8)-10(-6) M). ET-1 did not promote the mobilization of intracellular calcium ions and the enhancing effect of ET-1 did not change when calcium ions were depleted. These findings indicate that ET-1 is a potent modulator of human neutrophils and may thus contribute to the inflammatory process.

Fluoride activates diradylglycerol and Superoxide generation in human neutrophils via PLD/PA phosphohydrolase-dependent and -independent pathways

In contrast to the rapid, ethanol-inhibited Superoxide generation by the receptor-linked agonist formyl-methionyl-leucyl-phenylalanine (fMLP), fluoride-activated Superoxide generation occurs after a prolonged lag, and as shown herein is relatively ethanol-insensitive. We have investigated fluoride-activation of diradylglycerol generation and phospholipase D activity. Fluoride induces a very large increase in diradylglycerol mass (both 1,2-diacylglycerol (DAG) and 1- O-alkyl,2-acylglycerol (EAG)), with kinetics similar to Superoxide generation. Unlike fMLP-activated diglyceride generation which is completely inhibited by ethanol, that produced by fluoride is only partially (30%) blocked. When the phosphatidylcholine pool is 3H-prelabeled, fluoride activates both [ 3H]phosphatidic acid (PA) and [ 3H]diglyceride generation with similar kinetics. Partial inhibition of the production of these species by ethanol was seen, coincident with the appearance of [ 3H]phosphatidylethanol, indicating phospholipase D-dependent transphosphatidylation had occurred. The data are consistent with the fluoride activation of PA and diglyceride generation by both phospholipase D-dependent and -independent (presumably phospholipase C) mechanisms.

Priming effects of 2,3-dibenzylbutane-1,4-diol(mammalian lignan) on superoxide generation in human neutrophils

Priming effects of 2,3-dibenzylbutane-1,4-diol(mammalian lignan) on superoxide generation in human neutrophils

Synergism between phorbol ester and A23187 in Superoxide production by neutrophils

Concentrations of phorbol myristate acetate and the calcium ionophore, A23187, which by themselves are minimally effective in stimulating Superoxide generation in human neutrophils show marked mutual potentiation when given together. This supports the hypothesis that synergism between cytosolic calcium and protein kinase C is involved in the stimulus/activation coupling of the respiratory burst in the neutrophil. Neutrophil Phorbol ester Protein kinase C Calcium