The guinea pig neutrophil calcium-dependent lysosomal enzyme secretory process

Inhibition by nonsteroidal anti-inflammatory drugs of superoxide production and granule enzyme release by polymorphonuclear leukocytes stimulated with immune complexes or formyl-methionyl-leucyl-phenylalanine

The effects of nonsteroidal anti-inflammatory agents on superoxide production and granule enzyme release by human polymorphonuclear leukocytes stimulated with either formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe] or immune complexes were investigated. Cytochrome c reduction and the release of lysozyme, beta-glucuronidase, myeloperoxidase and gelatinase were measured. Auranofin, phenylbutazone, sulfasalazine and the phospholipase A2 inhibitor, 4-bromophenacyl bromide, strongly inhibited these responses in fMet-Leu-Phe stimulated cells, at concentrations below 50 microM. Indomethacin, piroxicam, mefenamic acid, primaquine and quinacrine at 50-250 microM were inhibitory. Up to 1 mM ibuprofen and chloroquine inhibited superoxide production but had little effect on degranulation. With cells stimulated by IgG aggregates (immune complexes), up to 1 mM ibuprofen, mefenamic acid and piroxicam did not inhibit either response. Indomethacin, phenylbutazone, sulfasalazine and primaquine inhibited, but considerably higher concentrations were required than with fMet-Leu-Phe. Quinacrine inhibited superoxide production equally well with both stimuli but inhibited enzyme release only with fMet-Leu-Phe. Only auranofin, 4-bromophenacyl bromide, and the weakly effective chloroquine exerted approximately the same effect with both stimuli. D-Penicillamine did not affect enzyme release with either stimulus and interfered in the superoxide assay. Gelatinase release induced by fMet-Leu-Phe was affected to the same extent, or slightly more, than release of the other granule enzymes. With immune complexes, there was only modest inhibition of gelatinase release by any of the drugs at 250-1000 microM. Our results reinforce previous observations that many anti-inflammatory drugs affect neutrophil functions, but their effects vary with stimulus. The relative insensitivity of immune complex-induced responses to most of the drugs must be taken into account when considering their mode of action.

Effect of indomethacin on human neutrophil chemiluminescence and microbicidal activity

The action of indomethacin on the bactericidal processes and chemiluminescent activity of human neutrophils was examined. Indomethacin substantially reduced the ability of neutrophils to kill Staphylococcus aureus and Escherichia coli and impaired their ability to generate both native and luminol-dependent chemiluminescence (CL). In contrast to these effects, indomethacin exerted an amplifying effect on lucigenin-sensitized phagocytically induced CL. The data suggests that indomethacin interferes with neutrophil myeloperoxidase-mediated CL and microbial killing, while substantially augmenting PMN superoxide-forming activity.

Phospholipid-sensitive Ca2+-dependent protein kinase and its substrates in human neutrophils

Phospholipid-sensitive Ca2+-dependent protein kinase (PL-Ca-PK) was found to be present at a high level in human neutrophils, with its activity localized in the particulate fraction. In contrast, cyclic AMP-dependent protein kinase (A-PK) and cyclic GMP-dependent protein kinase (G-PK), present at lower levels compared to PL-Ca-PK, were localized in the cytosolic fraction. Phosphorylation of several endogenous proteins (mol. wts. 89,000, 38,000, 34,000, 17,000 and 15,000), also localized in the particulate fraction, was stimulated specifically by a combination of phosphatidylserine and Ca2+, whereas no substrate proteins were observed for the calmodulin-sensitive Ca2+-dependent protein kinase system under the same incubation conditions. Although no substrate proteins for G-PK were detected, one substrate (mol. wt. 19,000) for A-PK was observed. Phosphorylation of substrates for PL-Ca-PK, but not that for A-PK and for enzymes independent of Ca2+ or cyclic AMP, was inhibited by a variety of agents, including trifluoperazine, W-7 [N-(6-aminohexyl)-5-chloro-1-naphthalene-sulfonamide], adriamycin, palmitoylcarnitine, and melittin. The present findings suggest that the phospholipid/Ca2+-stimulated protein phosphorylation system may be important in the membrane associated functions of human neutrophils.

Properties of calcium ionophore-induced generation of superoxide anion by human neutrophils

Exposure of human neutrophils to the calcium ionophore, A23187, eventuates in a time- and concentration-dependent generation of superoxide anion (O2-) in the presence but not absence of extracellular calcium. The selective requirement for calcium is demonstrated by the observation that magnesium caused a dose-related inhibition of A23187-stimulated O2- generation. Preincubation of neutrophils with cytochalasin B prior to their interaction with A23187 results in a significant enhancement of O2- production. The activity of the O2--generating system was maximum at 37 degrees C and was significantly curtailed at lower and higher temperatures. A23187-induced O2- generation was inhibited by the sulfhydryl reagents. N-ethyl maleimide (NEM) and iodoacetic acid (IA), and by the metabolic inhibitor 2-deoxy-D-glucose (2-DG) in the absence of glucose and cytochalasin B. Cyanide was inactive. Therefore, A23187 represents a useful pharmacologic probe for investigating the divalent cation and metabolic requirements of the neutrophil O2--generating system.

Properties of concanavalin A-elicited granule exocytosis from human polymorphonuclear neutrophils

Exposure of human neutrophils to concanavalin A (Con A) resulted in a time- and concentration-dependent extracellular release of granule-associated lysozyme but not beta-glucuronidase or cytosolic lactate dehydrogenase. Maximum extrusion of lysozyme occurred 30 min after cell contact with Con A. The percent of total granule enzyme activity discharged is insignificant when cells are not preincubated with cytochalasin B prior to being exposed to Con A (5-50 micrograms/ml). Granule enzyme release from Con A-treated cells is markedly inhibited by alpha-methyl-D-mannoside. Con A-elicited extrusion of lysozyme is reduced significantly, but not abolished, in the absence of extracellular calcium. However, contact between neutrophils and EGTA in calcium-free medium had no effect on Con A-stimulated release of granule enzymes. 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8), an antagonist of intracellular calcium, caused a dose-dependent inhibition of lysozyme discharge from Con A-treated neutrophils. The activity of TMB-8 could be abrogated with the addition of calcium, but not magnesium, to the extracellular medium. Therefore, Con A and TMB-8 should serve as useful tools for elucidating the mechanism of granule enzyme release from neutrophils.

Characteristics of N-formyl-methionyl-leucyl-phenylalanine as an inducer of lysosomal enzyme release from human neutrophils

N-formyl-methionyl-leucyl-phenylalanine (FMLP) stimulated a time- and concentration-dependent release of granule associated beta-glucuronidase and lysozyme but not cytoplasmic lactate dehydrogenase from human neutrophils. Maximum discharge of lysome activity released is insignificant when cells are not preincubated with cytochalasin B prior to being exposed to FMLP (10(-10)-10(-7) M); although 11.2 +/- 1.3 and 12.4 +/- 1.1% of total activity for beta-glucuronidase and lysozyme, respectively, is secreteer, had no effect on FMLP-elicited lysosomal enzyme extrusion. 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate hydrochloride (TMB-8), a purported antagonist of intracidating the role of calcium in the mechanism of lysosomal enzyme release.