Production In Polymorphonuclear Leukocytes Research Articles

Imipenem, a carbapenem type antibiotic, does not alter pharmacokinetics of a model drug nabumetone

Reported here are the results of a study carried out in order to assess the possible influence of the major circulating active metabolite of nabumetone, 6-methoxy-2-naphthylacetic acid, on some aspects of polymorphonuclear leukocytes activation. The action of 6-methoxy-2-naphthylacetic acid was tested on the following features of polymorphonuclear leukocytes activation: reactive oxygen species production in polymorphonuclear leukocytes stimulated with different agonists, reactive oxygen species production in polymorphonuclear leukocytes treated with pertussis toxin, NADPH-oxidase activity. The findings showed that 6-methoxy-2-naphthylacetic acid decreased reactive oxygen species production in polymorphonuclear leukocytes stimulated with N-formyl-methionyl-leucyl-phenylatanine, phorbol myristate acetate, and opsonized zymosan, but failed to provoke a decrease of reactive oxygen species production when the cells were stimulated with calcium ionophore A23187. Moreover, 6-methoxy-2-naphthylacetic acid did not influence the transduction of the signal following the binding of stimuli to membrane receptors, and NADPH-oxidase activity. Finally, our findings showed that 6-methoxy-2-naphthyl acetic acid had no scavenger effect on reactive oxygen species production.

Ca2+/calmodulin-dependent protein kinase II inhibitors potentiate superoxide production in polymorphonuclear leukocytes.

The possible role of Ca2+/calmodulin-dependent protein kinase II (CaMK II) in superoxide anion (O2-) production induced by formyl-methionyl-leucyl-phenylalanine (FMLP) was investigated in mouse polymorphonuclear leukocytes (PMNs). KN-93 and KN-62, specific CaMK II inhibitors, augmented FMLP-induced O2- production. KN-92, an analogue which did not inhibit CaMK II, did not affect O2- production. W-7, a calmodulin inhibitor, augmented O2- production when administered at 30 mM for 5 min. KN-93 and recombinant mouse tumour necrosis factor-alpha (rmTNF-alpha) each augmented the maximal production of O2- induced by FMLP, and an additive effect of a combination of KN-93 and rmTNF-alpha was observed. CaMK II activity in the PMNs was increased by FMLP, and the increase was inhibited by KN-93 but not by rmTNF-alpha. These results suggest that the inhibition of CaMK II resulted in the augmentation of FMLP-induced O2- production in PMNs by a mechanism different from that of the augmentation shown by TNF-alpha.

Effects of Hyperoxia and Nitric Oxide on Endogenous Nitric Oxide Production in Polymorphonuclear Leukocytes

Background: Exposure to hyperoxia and nitric oxide (NO) occur frequently during the treatment of neonatal hypoxic pulmonary failure. Objective: The aim of the study was to quantify the endogenous synthesis of NO in neonatal polymorphonuclear neutrophils following exposure to hyperoxia and NO in vitro. Methods: Neonatal cord blood was exposed to room air, 25, 30 and 100% oxygen and 10 or 20 ppm NO added to the different oxygen concentrations for up to 30 min. 4,5-Diaminofluorescein diacetate (DAF-2 DA) is an intracellular dye used to measure real-time changes in NO levels in vivo. The molecular structure of DAF-2 DA changes upon contact with NO to its oxidized and fluorescent form diaminofluorescein-triazol (DAF-2T) and after being hydrolyzed by intracellular esterases cannot leave the cell. DAF-2 DA signals following equilibration with room air were used as controls. Results: Exposure to 100% oxygen increased NO production significantly when compared to 20 ppm NO plus 100% oxygen (p = 0.031) and to 20 ppm NO alone (p = 0.006). 10 ppm NO produced a similar effect. Significant increases in NO production were also noticed following exposure to 25% oxygen. This increase was already present after 10 min of oxygen exposure. Conclusion: These findings support the propagated avoidance of hyperoxia not only in preterm infants, but also in term neonates.

Benidipine, an anti-hypertensive drug, inhibits reactive oxygen species production in polymorphonuclear leukocytes and oxidative stress in salt-loaded stroke-prone spontaneously hypertensive rats

Oxidative stress is associated with exacerbation of renal injuries in hypertension. In clinical studies benidipine hydrochloride (benidipine), a dihydropyridine calcium channel blocker with antioxidant activity, reduced oxidative stress. However, the mechanism of suppression of oxidative stress remains to be fully characterized. Reactive oxygen species production by polymorphonuclear leukocyte plays important pathological roles in hypertension. Therefore, we examined the effects of benidipine both on reactive oxygen species production of human polymorphonuclear leukocytes and oxidative stress of an animal model. Human peripheral polymorphonuclear leukocytes or polymorphonuclear leukocyte-like differentiated HL-60 cells were used to examine effects of benidipine (0.1–30 μM) on formyl-Met-Leu-Phe-induced reactive oxygen species production, calcium mobilization, NADPH oxidase activation and phosphorylation of protein kinase C substrates. High-salt (8% NaCl) loaded stroke-prone spontaneously hypertensive rats were treated with or without benidipine (1, 3, 10 mg/kg/day) for 2 weeks, and thiobarbituric acid reactive substances, a plasma oxidative stress marker, and renal expression of oxidative stress-induced genes were measured. Benidipine concentration-dependently suppressed formyl-Met-Leu-Phe-induced reactive oxygen species production in polymorphonuclear leukocytes more potently than other calcium channel blockers such as amlodipine, azelnidipine, nitrendipine and nifedipine. Benidipine partially inhibited all of intracellular Ca 2+ elevation, protein kinase C activation and NADPH oxidase activation. Salt loading in stroke-prone spontaneously hypertensive rats augmented plasma thiobarbituric acid reactive substances levels; renal dysfunction; and renal expression of transforming growth factor-β, collagen I and collagen III mRNAs; which were attenuated by benidipine treatment. These results indicate that benidipine prevents the polymorphonuclear leukocyte-derived reactive oxygen species production, which is due at least in part to its antioxidant action and inhibition of Ca 2+/protein kinase C/NADPH oxidase signaling. The attenuation of reactive oxygen species production might contribute to the drug's reduction of oxidative stress and renal injuries in hypertension.

Suppression of 5-lipoxygenase activity by anionic cholesterol derivatives

5-Lipoxygenase (5-LO) is a key enzyme involved in leukotriene (LTs) biosynthesis which act as host defense mediators, and inflammatory agents as well. In this work the influence of anionic cholesterol derivatives on 5-LO activity has been investigated. Cholesterol sulfate activated human polymorphonuclear leukocytes (PMNL) and stimulated their adhesion to endothelium and collagen. Cholesterol sulfate and cholesterol phosphate suppressed leukotriene production in PMNL and in rat RBL-1 cells. Kinetic characteristics of this process are presented. Cholesterol phosphate (charge -2) was shown to be more potent inhibitor then cholesterol sulfate (charge-1) in all experiments. We suppose that this fact highlights the importance of negatively charged ester groups to suppress 5-LO activity.

The Toll‐like receptor 7/8‐ligand resiquimod (R‐848) primes human neutrophils for leukotriene B4, prostaglandin E2 and platelet‐activating factor biosynthesis

Toll-like receptors (TLR) recognize pathogen-associated molecular patterns and play important roles in the innate immune system. While single-stranded viral RNA is the natural ligand of TLR7/TLR8, the imidazoquinoline resiquimod (R-848) is recognized as a potent synthetic agonist of TLR7/TLR8. We investigated the effects of TLR7/8 activation on lipid mediator production in polymorphonuclear leukocytes exposed to R-848. Although R-848 had minimal effects by itself, it strongly enhanced leukotriene B4 formation on subsequent stimulation by fMLP, platelet-activating factor, and the ionophore A23187. R-848 acted via TLR8 but not TLR7 as shown by the lack of effect of the TLR7-specific ligand imiquimod. Priming with R-848 also resulted in enhanced arachidonic acid release and platelet-activating factor formation following fMLP stimulation, as well as enhanced prostaglandin E2 synthesis following the addition of arachidonic acid. Western blot analysis demonstrated that R-848 induced the phosphorylation of the cytosolic phospholipase A2alpha, promoted 5-lipoxygenase translocation and potently stimulated the expression of the type 2 cyclooxygenase. Bafilomycin A1, an inhibitor of endosomal acidification, efficiently inhibited all R-848-induced effects. These studies demonstrate that TLR8 signaling strongly promotes inflammatory lipid mediator biosynthesis and provide novel insights on innate immune response to viral infections.

Role of Ca2+ in activation of reactive oxygen species production in polymorphonuclear leukocytes during tumour growth in rats

The role of Ca(2+) ions in PMA-induced generation of reactive oxygen species (ROS) by polymorphonuclear leukocytes (PMNL) was studied during Zajdela hepatoma growth in the peritoneal cavity of rats. In PMNL from control healthy animals, a manifold Ca(2+)-induced enhancement of ROS generation and its significant reduction in the presence of Ca(2+) binding agent (BAPTA-AM) were observed. In contrast, ROS generation by PMNL from tumour-carrying animals dramatically increased in Ca(2+)-free medium, being practically insensitive to the agents, which can increase or decrease intracellular Ca(2+) levels. Free cytosolic Ca(2+) ([Ca(2+)](i)) in control PMNL was found to be relatively low ( approximately 250 nmol/L), rising slowly after Ca(2+) addition and further to two-fold in the presence of Ca(2+) and ionomycin in the incubating medium. Tumour growth in animals was accompanied with a significant [Ca(2+)](i) elevation. In Ca(2+)-free medium, [Ca(2+)](i) elevation was up to 480 nmol/L in tPMNL with the additions of Ca(+) and ionomycin as well as EGTA and ionomycin being able to increase [Ca(2+)](i) to 700-900 nmol/L onward. It was concluded that a higher Ca(2+) permeability of the plasma membrane and higher Ca(2+) accumulation in intracellular pools of PMNL was developed at the advanced stages of malignant disease. These results indicate the primed state of circulating PMNL and the independence of PMA-induced ROS generation at intra- and extracellular Ca(2+) levels at the advanced stages of tumour growth in animals.

Nongenomic effect of thyroid hormone on free-radical production in human polymorphonuclear leukocytes

Over the past few years increasing evidence has suggested the nongenomic effects of thyroid hormone, such as the activation of the signal transduction pathways and the activation of nuclear factor-kappaB by the induction of oxidative stress. The present study was undertaken to investigate the effect of thyroid hormone on human polymorphonuclear leukocytes (PMNLs) which are known as important sources of reactive oxygen species in the circulation. The production of superoxide anion (O2-) and the activity of myeloperoxidase were determined in the presence and absence of several inhibitors of the signalling pathway. L-thyroxine (T4) l-3,5,3'-tri-iodothyronine (T3) and L-3,5-di-iodothyronine (T2) stimulated O2- production in PMNLs in a dose-dependent manner within a few minutes of addition to cells. Thyroid hormone-stimulated O2- production was partially inhibited by pertussis toxin, an inhibitor of GTP-binding G protein, and was completely abolished by the protein kinase C inhibitors calphostin C and Ro-32-0432, and by a calcium chelator (BAPTA; bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid). Thyroid hormone stimulated myeloperoxidase activity and induced 125I- incorporation into PMNLs. Furthermore, thyroid hormone pre-incubation enhanced O2- production for n-formyl-methionyl-leucyl- phenylalanine (FMLP) stimulation. In conclusion, novel nongenomic actions of thyroid hormone, the induction of superoxide anion production and the stimulation of myeloperoxidase activity in PMNLs were demonstrated. The induction of O2- production requires calcium and is mediated by a pertussis toxin-sensitive G protein via stimulation of protein kinase C(s). These results suggest the existence of a membrane-bound binding site for thyroid hormone in PMNLs and a physiological role for thyroid hormone in the cellular defence mechanisms by stimulating free-radical production.

Activated polymorphonuclear leukocytes enhance production of leukocyte microparticles with increased adhesion molecules in patients with sepsis.

Leukocyte microparticles (MPs) derived from polymorphonuclear leukocytes (PMNLs) have been recently found to be activators of vascular endothelium in vitro. The precise role of leukocyte MPs has not been clarified in patients suffering severe insult. The objective of this study was to evaluate production of leukocyte MPs and expression of adhesion molecules on the MP surface in patients with sepsis. Twenty-one patients with severe infection (fulfilling the criteria of sepsis with serum C-reactive protein > 10 mg/dL) and 21 healthy volunteers were included as study subjects. Production of leukocyte MPs, expression of CD11b on the MPs, and oxidative activity of PMNLs were measured by flow cytometry in the presence and absence of formyl-methionyl-leucyl-phenylalanine. CD11b expression was evaluated according to the MP size (more than, equal to, or less than 1.0 microm). Soluble E-selectin, thrombomodulin, and PMNL elastase were also measured in blood. Production of leukocyte MPs and superoxide production in PMNLs with and without formyl-methionyl-leucyl-phenylalanine increased significantly in patients with sepsis in comparison with production in normal volunteers. In patients with sepsis, expression of CD11b was also markedly enhanced on MPs less than 1.0 microm in diameter in comparison with expression in control subjects. Levels of soluble E-selectin, thrombomodulin, and PMNL elastase in blood were significantly increased in patients with sepsis. We succeeded in detecting leukocyte MPs visually by fluorescence microscopy. Activated PMNLs enhance production of leukocyte MPs with increased adhesion molecules in patients with sepsis. Activated leukocyte MPs may play a role in the pathogenesis of endothelial activation and leukocyte-endothelium interaction in the presence of sepsis.

Influence of nitric oxide on the in vitro antiaggregant effect of ticlopidine

The aim of this study was to evaluate the influence of leukocyte nitric oxide (NO) production on the antiplatelet aggregant effect of aspirin and ticlopidine. This in vitro study was done with platelets (platelet-rich plasma, PRP) and polymorphonuclear leukocytes (PMNLs) separated from samples of human blood. Collagen-induced platelet aggregation and calcium-dependent NO production by PMNL were quantified. The inhibition of NO production in PRP significantly reduced the antiaggregant affect of aspirin (IC 50 2.64-fold greater), whereas it had no significant effect on the effect of ticlopidine (IC 50 1.03-fold greater). Incubating PMNL in PRP increased the antiaggregant effect of both aspirin (IC 50 5.09-fold lower) and ticlopidine (IC 50 10.16-fold lower). The inhibition of NO production in PMNL significantly reduced the antiaggregant effect of both aspirin (IC 50 2.21-fold greater) and ticlopidine (IC 50 3.26-fold greater). Both drugs increased leukocyte NO production. The concentration of aspirin that raised NO production by 50% was greater than 1000 μM, whereas the concentration of ticlopidine that led to this effect was 9.14±0.87 μM. We conclude that the effect of ticlopidine on leukocyte NO production may constitute an addition mechanism to the IIb/IIIa glycoprotein complex inactivation in the inhibition of platelet activation.

ChemInform Abstract: Effects of BX661A (I), a New Therapeutic Agent for Ulcerative Colitis, on Chemotaxis and Reactive Oxygen Species Production in Polymorphonuclear Leukocytes in Comparison with Salazosulfapyridine and Its Metabolite Sulfapyridine.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Perioperative nutrition

Perioperative nutrition

Effects of 3-phenylamino-l,2-propanediol and its mono- and dioleylesters on the production of reactive oxygen metabolites in human polymorphonuclear leukocytes

Human polymorphonuclear leukocytes (PMNL) were exposed to 3-phenylamino-l,2-propanediol (PAP) or to its monoor dioleylesters. The dioleylester of PAP (140 μM) slightly increased the production of reactive oxygen metabolites (ROM) from 8 ± 2 mV to 18 ± 3 mV, whereas PAP and its mono-oleylester were without any effect on ROM production in PMNL. None of the compounds were able to modulate formyl-Methionyl-Leucyl-Phenylalanineinduced production of ROM. Moreover, PAP did not have any effect on the production of ROM induced by phorbol myristate acetate (PMA). On the other hand, both monoand dioleylesters of PAP dose-dependently inhibited PMA-induced production of ROM. The dioleylester of PAP, at a concentration of 14 μM, inhibited PMA-induced production of ROM by 79%, whereas a 2.3 mM concentration of mono-oleylester of PAP was required for 65% inhibition of PMA-induced production of ROM. Moreover, both esters of PAP shifted the peak production of ROM by PMA to a later time-point. Our results suggest that monoand dioleylesters of PAP modulate the responses of PMNL upon stimulation with PMA, whereas PAP does not have any effect on PMA-induced ROM production in PMNL. © 1997 Elsevier Science Ireland Ltd.

Effect of Insulin on Hydrogen Peroxide Production by Human Polymorphonuclear Leukocytes

This study evaluated the effect of insulin on the respiratory burst of human polymorphonuclear leukocytes (PMNLs) and the signalling pathways involved in this process, especially the involvement of protein kinase C (PKC). Isolated human PMNLs from healthy volunteers were incubated with different concentrations of insulin (10-10-10-7 mol/l) and for different durations of incubation (5-90 min). The intracellular production of hydrogen peroxide (H2O2) was detected employing a previously validated flow cytometric assay using 2',7'-dichlorofluorescein-diacetate (DCFH-DA) as a marker for H202 production. Specificity of insulin action was verified using an insulin antagonist (the monoclonal antibody MA-10). To identify the signalling pathway involved, we used; (a) monoclonal antibody MA-5, directed against the alpha-subunit of the insulin receptor, that partially mimics insulin without activating tyrosine kinase; (b) H7, an inhibitor of PKC involved in O2- production in PMNLs, and (c) phorbol myristate acetate (PMA) that binds and stimulates PKC. Insulin caused a dose- and time-dependent stimulation of H202 release by human PMNLs. The effect of insulin was blocked MA-10. The actions of insulin and PMA on H2O2 release were additive, whereas the actions of MA-5 and PMA were not. H7 partially inhibited the H2O2 production stimulated by insulin and completely inhibited MA-5 action. We conclude that insulin stimulates, in a dose- and time-related manner, the respiratory burst of human PMNLs. PKC activation can only partially account for the intracellular mechanisms involved in this process.

Effect of Methylprednisolone on Plasma Lipid Peroxidation Induced by Lipopolysaccharide

The effects of methylprednisolone succinate (MP) on plasma lipid peroxidation, plasma SOD activity and superoxide production in polymorphonuclear leukocytes (PMNs) induced by lipopolysaccharide (LPS) were examined in rats in vivo and in vitro. In rats subjected to LPS treatment, plasma phosphatidylcholine hydroperoxide (PCOOH) levels significantly increased, and the plasma Cu,Zn-SOD activity decreased by about 75%. When rats were given 30 mg/kg of MP intravenously, MP suppressed the elevation of plasma PCOOH levels and partially inhibited the decrease in plasma Cu,Zn-SOD activity. MP also suppressed PMA-induced superoxide production in PMNs primed by LPS. In in vitro experiments, low concentrations of MP had no effect on NADPH-dependent lipid peroxidation, but 4 mM MP produced 50% inhibition. MP had little effect on PMA-induced superoxide production in PMNs primed by LPS. Moreover, MP had no radical-trapping effect on superoxide, hydroxyl radical and stable DPPH radical. These results suggest that the suppressive effect of plasma lipid peroxidation by MP is not due to radical-trapping effects or preventive anti-oxidation, but may involve the suppression of the lipid chain reaction in liver membrane resulting from PMA-induced superoxide anions generated by PMNs.

Nicotine and cotinine modulate eicosanoid production in human leukocytes and platelet rich plasma

We investigated the effects of nicotine and cotinine (0.5 nM-0.5 mM) on prostaglandin E 2 and leukotriene B 4 production in human polymorphonuclear leukocytes and on thromboxane B 2 formation in human platelet-rich plasma, stimulated by calcium ionophore A23187. Nicotine and cotinine dose-dependently increased prostaglandin E 2 synthesis in polymorphonuclear leukocytes from 25% (0.5 nM) up to nearly four-fold (0.5 mM). In concentrations found in the plasma of smokers, nicotine and cotinine increased prostaglandin E 2 production by 33% (50 nM) and 50% (500 nM), respectively. Nicotine and cotinine equipotentially reduced both leukotriene B 4 production in polymorphonuclear leukocytes and thromboxane B 2 production in platelet rich plasma, the inhibition increasing from 20% (0.5 nM) to 60% (0.5 mM). The stimulation of prostaglandin E 2 and inhibition of leukotriene B 4 and thromboxane B 2 production by nicotine and cotinine may due to the pyridine moiety that these compounds have in common.

Polymorphonuclear Leukocytes Activation: In Vitro Modulation by 6-Methoxy-2-Naphthylacetic Acid, The Major Active Metabolite of Nabumetone

Reported here are the results of a study carried out in order to assess the possible influence of the major circulating active metabolite of nabumetone, 6-methoxy-2-naphthylacetic acid, on some aspects of polymorphonuclear leukocytes activation. The action of 6-methoxy-2-naphthylacetic acid was tested on the following features of polymorphonuclear leukocytes activation: reactive oxygen species production in polymorphonuclear leukocytes stimulated with different agonists, reactive oxygen species production in polymorphonuclear leukocytes treated with pertussis toxin, NADPH-oxidase activity. The findings showed that 6-methoxy-2-naphthylacetic acid decreased reactive oxygen species production in polymorphonuclear leukocytes stimulated with N-formyl-methionyl-leucyl-phenylatanine, phorbol myristate acetate, and opsonized zymosan, but failed to provoke a decrease of reactive oxygen species production when the cells were stimulated with calcium ionophore A23187. Moreover, 6-methoxy-2-naphthylacetic acid did not influence the transduction of the signal following the binding of stimuli to membrane receptors, and NADPH-oxidase activity. Finally, our findings showed that 6-methoxy-2-naphthyl acetic acid had no scavenger effect on reactive oxygen species production.

Changes in free intracellular calcium and production of reactive oxygen metabolites in human leukocytes by soluble and particulate stimuli

Changes in free intracellular calcium concentration ([Ca 2+] i) and in the production of reactive oxygen metabolites (ROM) were studied in human polymorphonuclear leukocytes (PMNL) exposed to graded concentrations of formyl-methionyl-leucyl-phenylalanine (fMLP), a chemotactic peptide, phorbol myristate acetate (PMA), a stimulator of protein kinase C (PKC), quartz, or chrysotile. fMLP, quartz, and chrysotile induced a concentration-dependent elevation in [Ca 2+] i. PMA did not affect [Ca 2+] i. fMLP caused a rapid and transient increase in [Ca 2+] i, whereas that caused by quartz or chrysotile was slow and sustained. fMLP, PMA and quartz all caused a concentration-dependent ROM production in PMNL. Chrysotile also caused a concentration-dependent increase in ROM production, but the slope of the curve was more gentle, with the maximum response being only 25% of that caused by the other stimuli. fMLP caused a rapid and transient peak in ROM production at 5 min, PMA a peak at 15 min, whereas quartz and chrysotile induced a biphasic ROM production with peaks at 5 and 20 min, and at 18 and 28 min, respectively. These results suggest that [Ca 2+] i may have an important role in the production of ROM by PMNL after an exposure to fMLP, quartz, or chrysotile, and that the involvement of PKC in ROM production is possible.

Stimulation of Human Polymorphonuclear Leukocytes by Consecutive Doses of Quartz and Interactions of Quartz with fMLP

The role of free intracellular calcium [Ca 2+] i was studied in the production of reactive oxygen metabolites (ROM) by human polymorphonuclear leukocytes (PMNL) after a single or two repeated doses of quartz. The significance of [Ca 2+] i, in the production of ROM was also studied after a dose of quartz prior to, or after, a dose of formylmethionylleucylphenylalanine (fMLP). When the production of ROM and changes in [Ca 2+] i were measured after repeated stimulations of cells, the cells were always washed between stimulations. A dose of quartz elevated [Ca 2+] i in untreated and washed cells, whereas a second dose of quartz did not induce any further increase in [Ca 2+] i. On the contrary, quartz stimulated ROM production after both one and two consecutive doses. fMLP alone elevated [Ca 2+] i and increased the production of ROM. Quartz before fMLP did not modify fMLP-induced [Ca 2+] i increase, but attenuated fMLP-induced ROM production. Quartz-induced elevation of [Ca 2+] i, was not affected by a prior dose of fMLP, hut the production of ROM by quartz was greatly amplified by prior exposure of PMNL to fMLP. Thus, both quartz and fMLP increase the production of ROM by mechanisms in which [Ca 2+] i may have a key role. Priming of PMNL with fMLP prior to quartz seems to amplify quartz-induced ROM production but not to affect [Ca 2+] i. It is plausible that both [Ca 2+] i-dependent and -independent mechanisms may account for quartz-induced ROM production in PMNL.

Effects of ethanol on the chemotactic peptide-induced second messenger generation and superoxide production in polymorphonuclear leukocytes.

The generation of oxygen radicals by polymorphonuclear leukocytes (PMNL) plays a pivotal role for host defense. Since ethanol reduced FMLP- but not PMA-induced superoxide ion (O2-) formation by PMNL, the effects of ethanol on second messenger systems in PMNL were studied. FMLP induced a biphasic rise in cytosolic calcium concentrations, [Ca2+]i. Ethanol treatment abolished the second phase (believed to reflect Ca2+ influx), an effect also observed in PMNL treated with La3+ or suspended in Ca(2+)-free buffer. The FMLP-induced inositol trisphosphate generation was unaffected by ethanol, whereas diacylglycerol formation was, as expected, markedly reduced. Propranolol, an inhibitor of diacylglycerol formation from phosphatidic acid, caused a prolonged transmembrane influx of Ca2+ and partially reversed the inhibitory effect of ethanol on FMLP-induced O2- production. Thus, the ability of ethanol to inhibit FMLP-induced O2- generation in neutrophils seems to be due to both impaired influx of Ca2+ across the plasma membrane and reduced phospholipase D-mediated generation of phosphatidic acid.