Use of lipophilic probes of membrane potential to assess human neutrophil activation. Abnormality in chronic granulomatous disease

Effects of the skin mitogens tumor-promotor 12-O-tetradecanoylphorbol 13-acetate and divalent-cation-ionophore A23187 on ion fluxes and membrane potential in a murine epidermal cell line (HEL30) and in 3T3 fibroblasts

The transmembrane potential of HEL30 keratinocytes and 3T3 fibroblasts has been determined by measuring the distribution of labelled triphenylmethylphosphonium bromide. The tumor-promotor 12-O-tetradecanoylphorbol 13-acetate (1-5 microM) induces hyperpolarization in 3T3 cells but does not exert any effect on the membrane potential of keratinocytes, whereas the divalent cation ionophore A23187 (0.5 - 1 microM) hyperpolarizes keratinocytes and probably also 3T3 cells. Studies on Na+ and Rb+ fluxes, as well as with different inhibitors, indicate that the hyperpolarizing effect is the consequence of an increased Na+ influx which in turn stimulates the Na+/K+-dependent ATPase. No causal relationship seems to exist between the change of the membrane potential and arachidonic acid release (and subsequent prostaglandin synthesis) which is induced by both drugs in both cell lines. Since the induction of the arachidonic cascade (by both agents) as well as the stimulation of Na+ influx (by A23187) are found to be critically dependent on extracellular Ca2+ and are inhibited by 'Ca2+-blockers', it is concluded that both reactions are triggered by the same event (Ca2+ translocation) but proceed independently of each other. The release of arachidonic acid is already stimulated under conditions where a measurable influx of Ca2+ is not yet observed. This indicates a local mobilization of Ca2+, perhaps across the plasma membrane. It is concluded that monovalent cation fluxes and changes of the membrane potential are not critically involved in the stimulation of the arachidonic acid cascade and cellular proliferation by agents which induce epidermal hyperplasia in vivo.

Abnormal regulation of inflammatory skin responses in male patients with chronic granulomatous disease

A common characteristic of the response to infection seen in patients with chronic granulomatous disease (CGD) is an exaggerated and prolonged inflammatory response with frequent development of draining lymph nodes and granuloma formation. Recent reports of several CGD patients with minor but significant in vitro abnormalities of cellular and humoral components of neutrophil chemotactic responses would predict lessened responses to inflammatory stimuli. The following studies were, therefore, performed to assess in vivo inflammatory responses in patients with CGD. Twenty-four-hour Rebuck skin-window procedures were performed on eight patients (five male and three female) with CGD and on ten volunteers. The windows were changed 1, 3, 5, 8, 12, and 24 h after the abrasion. Quantitation of the skin windows was performed with the assistance of a microscope-image analyzer computer facility. Neutrophil accumulation into skin windows was normal in CGD patients throughout the first 5 h. However, during the 8- to 24-h period, when neutrophils characteristically disappear from normal inflammatory responses and are replaced by monocytes, there was abnormal persistence of PMN at the inflammatory foci in male but not in female CGD patients (P less than 0.05 for the comparison of the rates of decline of PMN, from hour 8 to hour 24, in five male CGDs and in 10 normals). Monocyte recruitment was normal. In one CGD male, the abnormal skin-window response was normalized while he was receiving white cell transfusions. The data indicate that there is an abnormal "turn off" of the acute inflammatory response in male CGD patients and support a modulatory role for products of oxidative metabolism on the inflammatory response.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic granulomatous disease, a heterogeneous syndrome

Chronic granulomatous disease (CGD) is a clinical syndrome, the unifying characteristics of which are a severe predisposition to bacterial and fungal infections, an impaired ability of phagocytic leukocytes to kill certain microorganisms and the failure of these cells to produce microbicidal oxygen metabolites. In CGD the causal biochemical defect and the mechanism of genetic transmission vary from family to family. At least six different molecular defects have been found to underly the X-linked and at least three other the autosomal recessive form of CGD. Diagnosis of carriers is possible in most instances, and prenatal diagnosis by fetoscopic placental vessel puncture has become feasible.

Granulocytes without degranulation: neutrophil function in granule-depleted cytoplasts

Neutrophils respond to a variety of stimuli by generating superoxide anion, degranulating, and aggregating. Because it has been suggested that fusion of granules with the plasmalemma (degranulation) is necessary for aggregation and superoxide anion generation, we have tested whether these responses can be demonstrated in "neutrophilic cytoplasts" (granule-free vesicles of cytoplasm enclosed by plasmalemma). When examined by electron microscopy, cytoplasts were found to be approximately 4 microns in diameter and essentially granule free. Cytoplasts exposed to fMet-Leu-Phe (0.1 microM) generated superoxide anion after a lag of 16 sec but released no detectable beta-glucuronidase, lysozyme, or elastase. Aggregation of cytoplasts, as measured by changes in light transmission, was also activated by fMet-Leu-Phe; no lag period was observed. Electron microscopy of the aggregates demonstrated clusters of cytoplasts with a scalloped appearance. Superoxide anion generation and aggregation of cytoplasts were also activated by phorbol 12-myristate 13-acetate, concanavalin A, and leukotriene B4. Exposure of cytoplasts to the dye 3,3'-dihexyloxacarbocyanine iodide (DiOC6(3)] led to dye uptake and enhancement of fluorescence, implying that the vesicles were sealed and maintained a membrane potential across the plasmalemma. Exposure of DiOC6(3)-loaded cytoplasts to fMet-Leu-Phe and PMA caused a rapid loss of dye fluorescence that was not inhibited by CN-, compatible with their lack of mitochondria. Exposure of dye-loaded cytoplasts to concanavalin A or leukotriene B4 caused an increase in fluorescence--i.e., a hyperpolarization. These results demonstrate that degranulation is not a prerequisite for aggregation or superoxide anion generation. The retention of ionic gradients and changes in membrane potential, as measured by DiOC6(3) fluorescence changes, suggest a fundamental role for ionic movements in activating superoxide anion generation and aggregation.

Activation of the respiratory burst enzyme in human polymorphonuclear leukocytes by chemoattractants and other soluble stimuli. Evidence that the same oxidase is activated by different transductional mechanisms

Chemoattractant-receptor coupling triggers several biologic responses in phagocytic cells including activation of the respiratory burst. Prior evidence in intact cells implied that stimulation of the respiratory burst by chemoattractants was by a mechanism different from other soluble agents suggesting the possibility that different oxidative enzymes were responsible. We now show that the chemoattractants N-formyl-methionyl-leucyl-phenylalanine and a split fragment of the fifth component of complement (C5a) stimulate an NADPH oxidase activity, measured in the 50,000-g particulate fraction from human polymorphonuclear leukocytes (PMN). Levels of oxidase activity stimulated by the chemoattractants were both time and dose dependent and required the presence of cytochalasin B during stimulation. In contrast, activation by two nonchemotactic stimuli, the ionophore A23187 and phorbol myristate acetate (PMA), did not require cytochalasin B. Temporal patterns of oxidase activation suggested that different stimuli follow different transductional pathways. Chemoattractant-mediated activation was immediate (no lag); peaked by 45 s and declined rapidly to approximately 50% of maximal by 2 min. In contrast, activation by A23187 or PMA had a 15-30-s lag and increased more slowly. Stimulation by A23187 peaked at 5 min, then declined. Stimulation by PMA plateaued at 20 min and did not decline by 90 min. Comparison of Km values for NADPH and NADH obtained by Lineweaver-Burk analysis of the oxidase activity stimulated by N-formyl-methionyl-leucyl-phenylalanine, A23187, and PMA suggested that the same enzyme was activated by all stimuli. Thus, chemoattractants and other soluble stimuli appear to activate the same respiratory burst enzyme in PMN but they utilize different transductional mechanisms and are regulated differently.

Depolarization and increased conductance precede superoxide release by concanavalin A-stimulated rat alveolar macrophages

Rat alveolar macrophages release superoxide into the extracellular medium when stimulated by concanavalin A. This process, the respiratory burst, is characterized by a delay between binding of the stimulus and release of superoxide. It has been proposed that a key event that occurs during this delay period is the alteration of membrane electrical potential. Microelectrode impalement was used to directly measure electrical properties of the plasma membrane. Upon addition of concanavalin A, the membrane potential depolarized 21%, and membrane electrical resistance decreased 16%. Parallel chemical measurement of superoxide release indicated that these changes in electrical properties precede the release of superoxide.

Dissociation of human neutrophil membrane depolarization, respiratory burst stimulation and phospholipid metabolism by quinacrine

Human neutrophils generate a respiratory burst with the elaboration of toxic oxygen metabolites upon appropriate stimulation. Subsequent to receptor-ligand interaction, the activation pathway of this burst is unknown. Here, attempts to correlate phospholipid turnover have demonstrated dissociation of lipid flux and burst activation. Quinacrine inhibited membrane depolarization, superoxide (O-2) generation, and net phosphatidylserine production with ID50-values of 16 microM and greater than 500 microM, respectively. The inhibitory profiles of these neutrophil activation parameters demonstrate a dissociation between membrane depolarization, respiratory burst stimulation, and phospholipid turnover.

Studies in normal and chronic granulomatous disease neutrophils indicate a correlation of tubulin tyrosinolation with the cellular redox state

A specific stimulation of tubulin tyrosinolation in human polymorphonuclear leukocytes (PMN) is induced by the synthetic peptide chemoattractant, N-formyl-methionyl-leucyl-phenylalanine (fMet-Leu-Phe), and this stimulation of tyrosinolation in PMN is completely inhibited in the presence of various reducing agents. Further studies to characterize the mechanism of stimulation of tyrosinolation in PMN have revealed that conditions that inhibited the respiratory burst in stimulated PMN, e.g., an anaerobic atmosphere, or addition of antioxidants such as cysteamine, azide, or 2,3-dihydroxybenzoic acid, also inhibited the peptide-induced stimulation of tyrosinolation in these cells. Moreover, the sulfhydryl reagent, N-ethylmaleimide, depressed tyrosinolation in resting PMN and completely inhibited the fMet-Leu-Phe-induced stimulation. In contrast, addition of diamide, which preferentially oxidizes cellular glutathione, significantly stimulated tyrosinolation both in resting and fMet-Leu-Phe-stimulated PMN. Furthermore, resting levels of tyrosinolation in seven patients with chronic granulomatous disease (CGD), whose oxidative metabolism is severely depressed, were 35-45% lower (P less than 0.01). Most strikingly, PMN from CGD patients failed to respond to fMet-Leu-Phe or the Ca2+-ionophore A23187, which also induced stimulation of tyrosinolation in normal resting PMN. Methylene blue normalized the depressed tyrosinolation in resting CGD PMN, although it did not increase tyrosinolation in stimulated PMN. These results are consistent with the idea that the characteristic activation of the oxidative metabolism and the associated changes in the redox state in stimulated PMN are coupled to the induction of stimulation of tubulin tyrosinolation in these cells.

Comparison of indirect probes of membrane potential utilized in studies of human neutrophils

Four indirect probes of membrane potential, triphenylmethylphosphonium ion (TPMP+), 3,3'dipentyloxacarbocyanine [di-O-C5(3)], 3,3'dipentylindocarbocyanine [di-I-C5(3)], and 3,3'dipropylthiodicarbocyanine [di-S-C3(5)] have been used to study neutrophil (PMN) activation. The data extend previous studies indicating that the cyanine dye di-S-C3(5) not only exhibits a different fluorescence response mechanism from di-O-C5(3) [and di-I-C5(3)] but also that the fluorescence of di-S-C3(5) is destroyed by reactive oxygen products produced by neutrophils following stimulation. When these aspects of the probes are taken into account, the interpretations of the results using all three cyanine dyes are identical. Studies with the isotope TPMP+ indicate that long incubations are necessary for PMN to fully equilibrate during which time the PMNs depolarize. Use of TPB-, to shorten the TPMP+ equilibration time, produces results identical with those obtained using the cyanine dyes. The cyanine dyes and TPMP+/TPB- are toxic to neutrophil functions although they do not cause cell death. Toxicity can be avoided by using low concentrations of di-O-C5(3) and di-I-C5(3) but cannot be avoided with di-S-C3(5) or TPMP+/TPB-. Using di-O-C5(3) with the fluorescence-activated cell sorter, we demonstrate that heterogeneity of neutrophil responsiveness confuses the interpretation of studies characterizing the ionic basis of the fluorescence responses stimulated by certain stimuli. We conclude that some of the discrepancies currently reported in the literature using these probes are not due to inherent differences in the ability of the different probes to monitor the same event (i.e., PMN membrane potential) but instead are due to failure to correct for probe-specific problems or response heterogeneity.

Ocular findings in patients with neutrophil dysfunction

Of 32 patients (19 females and 13 males, ranging in age from 2 to 44 years), nine had ocular problems related to neutrophil dysfunction. Four patients had blepharokeratoconjunctivitis and pannus formation. In one of these, severe visual loss secondary to corneal thinning and scarring occurred. Five patients had inactive chorioretinal scars without visual loss. Although some of the other 23 patients had minor ocular abnormalities, we could not demonstrate that they were related to the neutrophil dysfunction. However, none of the control subjects (20 patients with systemic lupus erythematosus and 20 randomly selected eye clinic patients) had lesions resembling those of the patients with neutrophil dysfunction. Fisher's exact test (one-tailed) gave the following values: P less than .03 for keratitis; P less than .01 for chorioretinal scars; and P less than .001 for keratitis and chorioretinal scars. Abnormal neutrophil function probably interferes with the control of normal eyelid flora and predisposes the eye to the development of marginal keratitis. Eyelid hygiene and topical administration of antibiotics and corticosteroids during inflammatory episodes may prevent the progression of corneal vascularization. The chorioretinal scars do not appear to be progressive.

Early changes in cyclic AMP and calcium efflux during phagocytosis by neutrophils from normals and patients with chronic granulomatous disease

During phagocytosis of serum-treated zymosan particles (STZ) human neutrophils respond within 5 sec by a two-fold increase in cAMP concomitantly with an increase in 45Ca-efflux from intracellular stores. The changes in cyclic AMP and calcium efflux during phagocytosis were essentially the same whether the cells were preincubated in the presence of 5 mM glucose or without glucose. However, the phagocytic capacity, and oxygen consumption and degranulation during phagocytosis were reduced about 20%-25% in the absence of glucose. Addition of 2-deoxyglucose and iodoacetamide, which results in depletion of cellular ATP, abolished the cAMP increments during phagocytosis and profoundly inhibited calcium efflux. At the same time, the phagocytic capacity and STZ-induced oxygen consumption and degranulation were severely impaired. The mitochondrial inhibitors, cyanide, azide, and antimycin A, in the presence of glucose, did not affect the cellular ATP levels. Neither were cAMP increments and calcium effluxes during phagocytosis affected by these drugs, and likewise these did not affect phagocytosis or the post-phagocytic events. Neutrophils from two patients with X-linked chronic granulomatous disease (CGD) and one patient with the autosomal recessive form elicited normal increases in cAMP levels and calcium effluxes after addition of STZ despite no increase in oxygen consumption showing that these early metabolic events are not affected by the lack of oxidase function.

Measurement of membrane potential in polymorphonuclear leukocytes and its changes during surface stimulation

The membrane potential of guinea pig polymorphonuclear leukocytes has been assessed with two indirect probes, tetraphenylphosphonium (TPP+) and 3,3'-dipropylthiadicarbocyanine (disS-C3-(5)). The change in TPP+ concentration in the medium was measured with a TPP+-selective electrode. By monitoring differences in accumulation of TPP+ in media containing low and high potassium concentrations, a resting potential of -58.3 mV was calculated. This potential is composed of a diffusion potential due to the gradient of potassium, established by the Na+, K+ pump, and an electrogenic potential. The chemotactic peptide fMet-Leu-Phe elicits a rapid efflux of accumulated TPP+ (indicative of depolarization) followed by its reaccumulation (indicative of repolarization). In contrast, stimulation with concanavalin A results in a rapid and sustained depolarization without a subsequent repolarization. The results obtained with TPP+ and diS-C3-(5) were comparable. Such changes in membrane potential were observed in the absence of extracellular sodium, indicating that an inward movement of sodium is not responsible for the depolarization. Increasing potassium levels, which lead to membrane depolarization, had no effect on the oxidative metabolism in nonstimulated or in fMet-Leu-Phe-stimulated cells. Therefore, it seems unlikely that membrane depolarization per se is the immediate stimulus for the respiratory burst.

Formyl peptide stimulation of superoxide anion release from lung macrophages: sodium and potassium involvement

We examined the role of the monovalent cations Na+ and K+ in the events encompassing the release of O-2 by alveolar macrophages after stimulation with formyl methionyl phenylalanine (FMP). This was accomplished by determining the effect of changing the extracellular [Na+] and/or [K+] on FMP-stimulated O-2 production; and measuring 22Na+, 42K+ and 86Rb+ influx and efflux and intracellular [K+] for control and FMP-stimulated alveolar macrophages. Stimulated O-2 production was relatively insensitive to changes in extracellular K+ or Na+ concentrations until the [Na+] was decreased below 35 mM. At 4 mM [Na+], the rate of O-2 production remained at 75% of the maximal rate observed at physiological concentrations of [Na+]. Both influx and efflux of 22Na+ were stimulated above control rates by FMP. The increased rates of fluxes lasted for a few minutes suggesting a transient increase in membrane permeability to Na+. Ouabain partially inhibited 22Na+ efflux but had no effect on O-2 release. The influx of 86Rb+ and 42K+ was not altered by the addition of FMP but was virtually abolished in the presence of 10 microM ouabain or 1 mM quinine. In the presence of extracellular calcium, FMP-stimulated a prolonged (greater than 20 minutes) increase in 86Rb+ or 42K+ efflux which was inhibitable by 1 mM quinine. In the absence of extracellular calcium, FMP stimulation of K+ efflux was greatly diminished and was not affected by quinine, although quinine still inhibited O-2 production under these conditions. It was also observed that there was a loss of intracellular K+ when cells were stimulated by FMP in the presence of Ca+2, but not in the absence of Ca+2. Taken together, these results suggest a minimal direct role, if any, for K+ in the events that lead to FMP-stimulated O-2 release by alveolar macrophages.

Tumor-promoter-resistant cells lack trisialoganglioside response

JB6 mouse epidermal cells shift irreversibly to tumor cell phenotype (anchorage independence and tumorigenicity) on treatment with phorbol esters and other tumor promoters. Exposure to phorbol 12-myristate 13-acetate (PMA) decreased the de novo synthesis of trisialoganglioside (GT) in these "promotable" JB6 cells to 5-10% of that of untreated cells. The GT decrease occurred consistently in promotion-sensitive cells and not in promotion-resistant variants. Insertion of GT into membranes of PMA-treated cells inhibited PMA promotion of transformation as measured by agar colony induction. This ability to inhibit promotion of transformation is specific to GT and is not shared by other sialoglycoconjugates, including gangliosides GM1, GD1a, and asialo-GM1. The mechanism of the blocking activity of GT must be distal to the binding of PMA to its receptors, as exogenously added GT does not inhibit specific binding of tritiated phorbol diester. GT is unable to block agar colony formation by transformed cell lines, showing that its level of action is at induction of the transformed phenotype rather than at expression of it.

Calcium movement and membrane potential changes in the early phase of neutrophil activation by phorbol myristate acetate: a study with ion-selective electrodes

To quantitate calcium movements and membrane potential changes in stimulated neutrophils, we have measured net fluxes of Ca2+ and of the lipophilic cation tetraphenyl phosphonium by a very sensitive ion-selective electrode system. Activation of neutrophils by 3 X 10(-8) M phorbol 12-myristate, 13-acetate induces a release of approximately 20% of total cell calcium, with an initial lag period of less than 10 s. The Ca2+ outflux is markedly reduced in ATP-depleted cells and in the presence of a calmodulin inhibitor, thereby suggesting that it occurs by activation of the ATP-driven Ca2+ pump of the neutrophil plasmalemma. Activation of neutrophils also induces a transiently increased exchange of medium 45Ca with cell calcium, which is measurable a few seconds after cell exposure to the stimulant and peaks at approximately 40 s. Stimulation of neutrophils after attainment of steady-state accumulation of tetraphenyl phosphonium (resting potential of -67 mV) results in a marked depolarization, with a lag period of approximately 60 s. The rate and extent of depolarization are reduced by 40 and 65%, respectively, in a low Na+ medium but are not modified by an inhibitor of anion exchange across membranes. A high-K+ medium depolarizes neutrophils without either modifying their resting oxidative metabolism or impairing stimulability by the phorbol ester. Phorbol 12-myristate, which also exhibits no effect on the oxidative metabolism of neutrophils, does not induce Ca2+ extrusion and membrane potential changes. The causal relationship between Ca2+ mobilization, membrane potential changes and activation of neutrophil functions is discussed.

Selective enrichment of NADPH oxidase activity in phagosomes from guinea pig polymorphonuclear leukocytes

Recent studies have demonstrated that the activated NADPH oxidase, the enzyme responsible for the stimulation of O2 consumption with O2 formation during phagocytosis, is located in the plasma membrane of leukocytes. The present work deals with whether the activation induced by phagocytosis involves the enzyme of the entire membrane or only that of the portion of the membrane that interacts with the phagocytosable particle and forms the phagosome. The results presented show that the activity of the NADPH oxidase of phagosomal membrane, isolated by centrifugation of homogenates on discontinuous sucrose gradients, is increased 12.6-fold with respect that of homogenate. In contrast, the activities of 5'-nucleotidase and of acid p-nitrophenyl phosphatase, enzyme markers of the plasma membrane not activated during phagocytosis and uniformly distributed on the entire membrane, are increased only about three-fold with respect to that of homogenate. These results indicate that during phagocytosis and activation of NADPH oxidase is a segmentary response that involves only the enzyme that forms the phagocytic vacuole. This fact is relevant for the function of toxic intermediates of oxygen reduction that are discharged in direct contact with the engulfed agent.

Sodium and potassium fluxes and membrane potential of human neutrophils: evidence for an electrogenic sodium pump

Sodium and potassium ion contents and fluxes of isolated resting human peripheral polymorphonuclear leukocytes were measured. In cells kept at 37 degrees C, [Na]i was 25 mM and [K]i was 120 mM; both ions were completely exchangeable with extracellular isotopes. One-way Na and K fluxes, measured with 22Na and 42K, were all approximately 0.9 meq/liter cell water . min. Ouabain had no effect on Na influx or K efflux, but inhibited 95 +/- 7% of Na efflux and 63% of K influx. Cells kept at 0 degree C gained sodium in exchange for potassium ([Na]i nearly tripled in 3 h); upon rewarming, ouabain-sensitive K influx into such cells was strongly enhanced. External K stimulated Na efflux (Km approximately 1.5 mM in 140-mM Na medium). The PNa/PK permeability ratio, estimated from ouabain insensitive fluxes, was 0.10. Valinomycin (1 microM) approximately doubled PK. Membrane potential (Vm) was estimated using the potentiometric indicator diS-C3(5); calibration was based on the assumption of constant-field behavior. External K, but not Cl, affected Vm. Ouabain caused a depolarization whose magnitude dependent on [Na]i. Sodium-depleted cells became hyperpolarized when exposed to the neutral exchange carrier monensin; this hyperpolarization was abolished by ouabain. We conclude that the sodium pump of human peripheral neutrophils is electrogenic, and that the size of the pump-induced hyperpolarization is consistent with the membrane conductance (3.7-4.0 microseconds/cm2) computed from the individual K and Na conductances.

Human neutrophil heterogeneity identified using flow microfluorometry to monitor membrane potential

Previous studies of neutrophil nitroblue tetrazolium dye reduction in response to endotoxin and rosetting of IgG-coated erythryocytes have suggested functional heterogeneity of peripheral blood neutrophils. In the following study we utilized flow microfluorometry and the membrane potential-sensitive fluorescent dye 3-3'-dipentyloxacarbocyanine to assess the heterogeneity of neutrophils upon activation by a variety of stimuli. Unstimulated neutrophils from normal subjects exhibited a unimodal distribution of fluorescence, suggesting that all the cells possessed the same resting membrane potential. As neutrophils aged (>5 h), some cells lost fluorescence producing a bimodal distribution. In studies with fresh cells, the secretagogue phorbol myristate acetate (20 ng/ml) stimulated a uniform loss of fluorescence (apparent depolarization). The chemoattractant N-formyl-methionyl-leucyl-phenylalanine (f-Met-Leu-Phe) (0.1 muM) caused the neutrophils to assume and maintain (for > 30 min) a bimodal fluorescence distribution in which 65+/-5% of the neutrophils first decreased and then increased fluorescence (apparent depolarization/partial repolarization), and 35+/-5% of the cells exhibited either an increase in fluorescence (apparent hyperpolarization) or no change. Treatment of neutrophils with cytochalasin B before stimulation caused the cells to respond homogeneously to f-Met-Leu-Phe. Additional studies using neutrophils from patients with chronic granulomatous disease, which exhibit abnormal membrane potential responses, indicated that this defect affected all such neutrophils uniformly. These observations demonstrate the need to investigate the physiological significance of the heterogeneity of neutrophil function and indicate that the f-Met-Leu-Phe-induced changes in membrane potential observed in bulk population cell studies are the summation of two different responses.

Inhibition of human polymorphonuclear leukocyte function by 2-cyclohexene-1-one. A role for glutathione in cell activation

2-cyclohexene-1-one and diethyl maleate specifically decrease reduced glutathione (GSH) levels in human polymorphonuclear leukocytes (PMN) by direct conjugation, and by interaction with the glutathione-s-transferase system. Using these two nontoxic reagents we have examined the effect of decreased GSH levels on five parameters of PMN activation: superoxide generation, release of the lysosomal enzymes lysozyme and beta-glucuronidase, and increases in the influx of Na+ and Ca2+. When PMN pretreated with 2-cyclohexene-1-one or diethyl maleate were incubated with formyl-methionyl-leucyl-phenylalanine (FMLP) or the proteolytic fragment of the fifth component membrane of complement, C5a, agents that interact with surface membrane receptors, increases in all five parameters were inhibited in a dose-dependent manner. For O-2 generation and lysosomal enzyme release the ID50 for 2-CHX-1 was 40--90 micrometers corresponding with a 30--50% decrease in intracellular GHS. In contrast stimulation of treated PMN by the divalent cation ionophore A23187 or 5-hydroxyeicosatetraenoic acid was much less sensitive to depressed GSH; the ID50 for 2-cyclohexene-1-one was 1 mM or greater, corresponding with an 80--90% decrease in GSH. The effect of lowered GSH was not the result of decreased binding of FMLP to surface receptors because [3H]-FMLP binding studies demonstrated a two- to three-fold increase in the number of available binding sites. These data indicate that normal GSH levels are necessary for the transduction of the activation signal from the exterior to the interior of the PMN, but once initiated the activation sequence proceeds normally despite markedly lowered intracellular GSH.

Abnormal responses of granulocytes in chronic granulomatous disease

Stimulation of normal granulocytes with chemotactic factor, phorbol myristate acetate, concanavalin A, and calcium ionophore results in rapid depolarization which precedes the 'respiratory burst'. Treatment of granulocytes in chronic granulomatous disease with these stimulants fails to generate chemiluminescence. This defect is associated with an absence of transmembrane potential shifts in response to treatment with chemotactic factor, phorbol myristate acetate, and concanavalin A while depolarization in response to A23187 is unaffected by this disease state.

Current view of neutrophil dysfunction: an integrated clinical perspective

Normal neutrophil function is dependent on the integration of chemotaxis, phagocytosis, degranulation and oxidative metabolism. The availability of in vitro assays for the separate quantitative evaluation of each function has permitted the definition of specific congenital and acquired neutrophil abnormalities, which are associated with defective host resistance. The appreciation of complex and often adverse effects of certain systemic diseases and drugs on neutrophil function as well as the use of new approaches to therapy suggest the importance of assessing the role of the neutrophil in states of impaired host defense.