Mechanisms of Regulating the Respiratory Burst in Leukocytes

McPhail, Linda C.; Snyderman, Ralph

doi:10.1007/978-1-4757-4862-8_9

Cited by 33 publications

(14 citation statements)

References 186 publications

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“…Alternatively, the 48-kD protein(s) may be a component(s) of NADPH oxidase; a protein of that molecular weight appears, albeit variably, in preparations of the purified oxidase flavoprotein (63). Finally, the 48-kD protein(s) could be a regulatory molecule(s), influencing one or more of several pathways (2,11,18,19,33,36) ofactivation of oxidative metabolism. Further efforts will be made to distinguish between these possibilities and to resolve the current discrepancies in the literature by fully characterizing the 48-kD protein(s).…”

Section: Discussionmentioning

confidence: 99%

“…The enzyme in PMN that triggers oxygen radical production is an activatable NADPH oxidase, whose mechanism of activation is still unknown. The active enzyme appears to be a multicomponent complex, most likely consisting of a flavoprotein and a unique low potential cytochrome, cytochrome b559 (2).…”

Section: Introductionmentioning

confidence: 99%

“…Until recently, activation of NADPH oxidase could only be achieved by stimulation of intact PMN with a wide variety of agents, including opsonized particles, phorbol esters, chemotactic peptides, and certain detergents (2). One characteristic these stimuli share is the ability to trigger activation of protein kinases inside the cell resulting in the phosphorylation of endogenous proteins (3)(4)(5)(6)(7)(8).…”

Section: Introductionmentioning

confidence: 99%

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Coregulation of NADPH oxidase activation and phosphorylation of a 48-kD protein(s) by a cytosolic factor defective in autosomal recessive chronic granulomatous disease.

Caldwell¹,

McCall²,

Hendricks³

et al. 1988

J. Clin. Invest.

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The mechanisms regulating activation of the respiratory burst enzyme, NADPH oxidase, of human neutrophils (PMN) are not yet understood, but protein phosphorylation may play a role. We have utilized a defect in a cytosolic factor required for NADPH oxidase activation observed in two patients with the autosomal recessive form of chronic granulomatous disease (CGD) to examine the role of protein phosphorylation in activation of NADPH oxidase in a cell-free system. NADPH oxidase could be activated by SDS in reconstitution mixtures of cytosolic and membrane subcellular fractions from normal PMN, and SDS also enhanced phosphorylation of at least 16 cytosolic and 14 membrane-associated proteins. However, subcellular fractions from CGD PMN plus SDS expressed little NADPH oxidase activity, and phosphorylation of a 48-kD protein(s) was selectively defective. The membrane fraction from CGD cells could be activated for NADPH oxidase when mixed with normal cytosol and phosphorylation of the 48-kD protein(s) was restored. In contrast, the membrane fraction from normal cells expressed almost no NADPH oxidase activity when mixed with CGD cytosol, and phosphorylation of the 48-kD protein(s) was again markedly decreased. Protein kinase C (PKC) activity in PMN from the two patients appeared to be normal, suggesting that a deficiency of PKC is not the cause of the defective 48-kD protein phosphorylation and that the cytosolic factor is not PKC.These results demonstrate that the cytosolic factor required for activation of NADPH oxidase also regulates phosphorylation of a specific protein, or family of proteins, at 48 kD. Although the nature of this protein(s) is still unknown, it may be related to the functional and phosphorylation defects present in CGD PMN and to the activation of NADPH oxidase in the cell-free system.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Coregulation of NADPH oxidase activation and phosphorylation of a 48-kD protein(s) by a cytosolic factor defective in autosomal recessive chronic granulomatous disease.

Caldwell¹,

McCall²,

Hendricks³

et al. 1988

J. Clin. Invest.

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“…The enzyme system responsible for this respiratory burst appears to be an NADPH oxidase that is inactive until the cells have been stimulated by a wide variety of phagocytic, inflammatory, and surface-reactive agents (1,2). The mechanisms that regulate the activation of this enzyme are not well understood.…”

Section: Introductionmentioning

confidence: 99%

Activation of the respiratory burst enzyme from human neutrophils in a cell-free system. Evidence for a soluble cofactor.

McPhail¹,

Shirley²,

Clayton³

et al. 1985

J. Clin. Invest.

324

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Activation of the respiratory burst in phagocytic cells, an important host defense process, is not yet well understood. We now report the development of a cell-free system for activation of NADPH oxidase, the respiratory burst enzyme, in human neutrophils. Activation was achieved by the addition of arachidonic acid to a postnuclear supernatant (500 g) from disrupted unstimulated cells (no arachidonate, 0.2; with arachidonate, 3.4 nmol superoxide anion/min per mg) and was dependent on both the concentration of arachidonate and on the amount of cellular material present. Activity stimulated by arachidonate appeared to be NADPH oxidase based on a Michaelis constant for NADPH of 32 jzM and a pH optimum of 7.0-75. Separation of the 500-g supernatant by high speed centrifugation revealed a requirement for both soluble and particulate cofactors. Activation of NADPH oxidase by arachidonate did not occur in the high speed pellet fraction from unstimulated cells but could be restored by the addition of the high speed supernatant. In addition, priming of intact neutrophils with low concentrations of the chemoattractant N-formyl-methionyl-leucyl-phenylhlanine or the tumor promoter phorbol myristate acetate replaced the soluble factor requirement for NADPH oxidase activation by arachidonate in the high speed pellet. This cell-free system can now be used to provide further insight into the biochemical basis of priming and the terminal mechanisms involved in the activation of NADPH oxidase.

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“…In fact, raising extracellular pH from 5 9 to 8 0 increased intracellular pH of activated cells from 6 8 to 8-1 [20], Thus, it is reasonable to speculate that under our experimental conditions, intracellular pH of stimulated PMN and monocytes was significantly decreased when they were cultured at pH 6 2, To our knowledge, there have been no previous reports concerning the effect of pH on oxygen-dependent cytotoxic responses mediated by phagocytic cells. Some reports have analysed, however, the effect of pH on the generation of superoxide anion by phagocytic cells, Simchowitz [20] has shown that superoxide anion production by FMLP-stimulated neutrophils was strongly inhibited (per cent inhibition > 80%) when it was assayed at extracellular pH of 6 2 instead of pH 7 4, Intracellular acidification was also associated with a dramatic reduction in the quantity of superoxide anion released by stimulated cells [20], McPhail et al [21,22] demonstrated that the activation of neutrophil NADPH oxidase, the respiratory burst enzyme, by arachidonic acid, examined in a cell-free system, shows an optimum pH of 7 0-7 5 that decreases about 50% when assayed at pH 6-0, CL response of phagocytic cells has been related to superoxide anion production and to peroxidase-catalysed reactions [23,24], In the present study, we showed that light emission by IC-stimulated neutrophils was significantly inhibited at pH 6 2 instead of pH 7 4. Taken together, these data suggest that the generation of oxidative products by stimulated phagocytic cells is partially inhibited at acidic pH.…”

Section: Discussionmentioning

confidence: 99%

Extracellular acidic pH modulates oxygen-dependent cytotoxic responses mediated by polymorphonuclear leucocytes and monocytes

Geffner

Trevani

Minnucci

et al. 1993

Clinical and Experimental Immunology

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SUMMARYIn the present study, we compared the ability of human neutrophils and monocytes to display oxygen-dependent cytotoxic responses at pH 7-4 and 6-2. Our results show that cytotoxicity induced by immune complexes (IC), zymosan, N-formyl-methionyl-leucyl-phenylalanine (FMLP) and concanavalin A (Con A) were markedly increased when they were carried out at pH 6-2 instead of pH 7-4. Cytotoxicity induced by phorbol myristate acetate (PM A), on the contrary, was significantly decreased at pH 6 2. It is noteworthy that cytotoxic responses induced by IC, zymosan and Con A were also increased when, 2 h after effector cell stimulation at pH 6 2, cytotoxicity was measured at pH 7 4. Finally, when we examined possible mechanisms involved in the augmentation of cytotoxicity, we observed that the oxidative response of IC-stimulated neutrophils, measured as chemiluminescence emission, was not increased at pH 6 2, on the contrary, it was significantly decreased. The relevance of these results is discussed.

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Mechanisms of Regulating the Respiratory Burst in Leukocytes

Cited by 33 publications

References 186 publications

Coregulation of NADPH oxidase activation and phosphorylation of a 48-kD protein(s) by a cytosolic factor defective in autosomal recessive chronic granulomatous disease.

Coregulation of NADPH oxidase activation and phosphorylation of a 48-kD protein(s) by a cytosolic factor defective in autosomal recessive chronic granulomatous disease.

Activation of the respiratory burst enzyme from human neutrophils in a cell-free system. Evidence for a soluble cofactor.

Extracellular acidic pH modulates oxygen-dependent cytotoxic responses mediated by polymorphonuclear leucocytes and monocytes

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