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M P Fletcher

Publications and source records attributed to M P Fletcher.

At least 19 recordsLinked to original sources
PubMed1992

Dose-response effects of dietary gamma-linolenic acid-enriched oils on human polymorphonuclear-neutrophil biosynthesis of leukotriene B4.

The dose-dependent effect of dietary supplemented gamma-linolenic acid (GLA, 18:3n-6)-enriched borage oil (Bor) and black-currant oil on the ability of calcium ionophore-activated human polymorphonuclear neutrophils (PMN) to generate leukotriene B4 (LTB4) was investigated in adult healthy human volunteers. Significant (P less than 0.05) elevation of dihomo-gamma-linolenic acid (DGLA, 20:3n-6), an elongation product of GLA, was revealed in PMN phospholipids after ingestion of either 0.48 or 1.5 g GLA-enriched oil/d. This elevation of DGLA in the PMN phospholipids paralleled the decreased capacity of calcium ionophore-activated PMN to generate LTB4. Although the inhibition of LTB4 was greater with the ingestion of 1.5 g GLA-enriched BOR/d, it was not significantly different from the ingestion of 0.48 g/d. Taken together, dietary ingestion of GLA-fortified oils does modulate PMN generation of proinflammatory LTB4.

Adult↗
PubMed1991

The second-generation antihistamines. What makes them different?

Physicians often are faced with the decision of whether to prescribe a drug for its positive therapeutic effects or avoid prescribing it because of unacceptable side effects. This dilemma can sometimes be eased by keeping current on new therapeutic options as they become available. The authors provide a useful update on the state of the art in antihistamine therapy.

Astemizole↗
PubMed1991

Moderate zinc deficiency in rhesus monkeys. An intrinsic defect of neutrophil chemotaxis corrected by zinc repletion.

Experimental animals fed zinc-deficient diets are well known for susceptibility to infections and impaired mitogen response and Ig production. However, the levels of zinc deficiency used have generally been severe, not comparable to human populations, and have not addressed neutrophil function. To address this issue we have studied the effect in rhesus monkeys of a well defined moderately zinc-deficient (MZ) diet on polymorphonuclear leukocyte (PMN) function. Female adult rhesus monkeys were fed either a control (100 micrograms Zn/g) or MZ (2 micrograms Zn/g) diet for 9 mo with quantitation of PMN chemotaxis, and phagocytosis of opsonized yeast. In addition, membrane potential and secretion responses (changes in 90 degrees light scatter) and changes in PMN shape (forward light scatter shifts) were also measured. When compared to the PMN of animals fed control diets, there was a significant reduction in chemotaxis to FMLP of MZ-fed monkey PMN. Although shape change, cell membrane depolarization, as well as phagocytosis were not significantly different among the two groups, the PMN of MZ animals had significantly lower relative loss of orthogonal light scatter (degranulation) due primarily to a lower resting orthogonal light scatter and also a smaller loss when stimulated with FMLP. In vitro addition of zinc to the cells (25 microM) did not improve chemotaxis, and in fact, was inhibitory for most control and zinc-deficient cells. However, after 2 wk of dietary zinc repletion (100 micrograms Zn/g), chemotaxis in the low zinc group was higher and comparable to the control response. These data indicate that zinc deficiency is associated with an intrinsic PMN defect that specifically affects chemotaxis and is corrected with dietary zinc repletion.

Animals↗
PubMed1991

Evaluation of prostaglandin E1 for prevention of respiratory failure in high risk trauma patients: a prospective clinical trial and correlation with plasma suppressive factors for neutrophil activation.

A group of 48 critically injured patients were entered into a prospective, double-blind, placebo-controlled trial to evaluate the efficacy of early infusion of PGE1 for reducing the incidence of severe respiratory failure and mortality. Secondary assessments examined the effects of the PGE1 infusion on plasma mediated suppression of PMN superoxide production and loss of PMN granule enzyme content. The incidence of severe respiratory failure was lower in the PGE1 group--13% versus 32%, but this did not reach significance. The overall morality was equivalent between the two groups--26% (PGE1) versus 28% (placebo). The suppressive activity of the patient plasma was assayed by measurement of normal PMN superoxide production relative to normal control plasma (ratio P:C). The baseline ratio P:C was 62 +/- 5% in the PGE1 group versus 60 +/- 5% in the placebo group. The day 1 plasma samples showed significant reversal of plasma suppressive activity in the PGE1 group--ratio P:C 88 +/- 5% versus 67 +/- 5% in the placebo group (P less than 0.02). In patients who received the full 7 days of infusion, the plasma suppressive activity remained significantly diminished in the PGE1 group--ratio P:C 77 +/- 4% versus 61 +/- 5% (P less than 0.04). The baseline lysozyme content of patient PMN's relative to that of normal control PMNs (ratio P:C) was 119 +/- 14% in the PGE1 group. A significant loss of lysozyme content was observed in the PGE1 group on day 1 of the infusion--ratio P:C 79 +/- 8% (P less than 0.03), and was associated with a reduction in the plasma suppressive activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Dietary supplementation with ethyl ester concentrates of fish oil (n-3) and borage oil (n-6) polyunsaturated fatty acids induces epidermal generation of local putative anti-inflammatory metabolites.

Clinical reports have attributed the amelioration of chronic inflammatory skin disorders to the presence of certain polyunsaturated fatty acids (PUFA) in dietary oils. To test the hypothesis of a local modulatory effect of these PUFA in the epidermis, the basal diet of normal guinea pigs was supplemented with ethyl esters of either fish oil [rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] or borage oil [rich in gamma-linolenic acid (GLA)]. Our data demonstrated that dietary oils influence the distribution of PUFA in epidermal phospholipids and the epidermal levels of PUFA-derived hydroxy fatty acids. Specifically, animals supplemented with ethyl esters of fish oil markedly incorporated EPA and DHA into epidermal phospholipids, which paralleled the epidermal accumulation of 15-hydroxyeicosapentaenoic acid (15-HEPE) and 17-hydroxydocosahexaenoic acid (17-HDoHE). Similarly, animals supplemented with esters of borage oil preferentially incorporated dihomogammalinolenic acid (DGLA), the epidermal elongase product of GLA, into the epidermal phospholipids, which also was accompanied by epidermal accumulation of 15-hydroxyeicosatrienoic acid (15-HETrE). By factoring the epidermal levels of the 15-lipoxygenase products and their relative inhibitory potencies, we evolved a measure of the overall potential of dietary oils to exert local anti-inflammatory effect. For example, the leukotriene inhibition potentials (LIP) of both fish oil and borage oil were greatly enhanced when compared to controls. Thus, the altered profiles of epidermal 15-lipoxygenase products generated from particular dietary oils may be responsible, at least in part, for reported ameliorative effects of oils on chronic inflammatory skin disorders.

Animals↗
PubMed1991

Role of granulocytes and C5a in myocardial response to zymosan-activated serum.

Although previous studies have demonstrated that complement (C)5a causes myocardial ischemia and mechanical dysfunction, the cardiac response of endogenously produced C5a and C5a des-Arg in zymosan-activated serum (ZAS) and the critical role of granulocytes in this process are poorly understood. Therefore, we compared the coronary and cardiac effects of ZAS and purified C5a and investigated the role of leukocyte adhesion-promoting receptors (i.e., CD11/CD18). Like purified C5a, ZAS (0.5 ml) significantly reduced coronary artery blood flow and regional segment shortening, whereas coronary venous granulocyte concentration and myocardial lactate extraction were significantly decreased. A monoclonal antibody (MoAb) to C5a/C5a des-Arg attenuated ZAS-induced cardiac alterations. Three minutes of continuous infusion of C5a or ZAS induced sustained decreases in coronary venous granulocyte concentrations, although coronary flow and segment shortening returned to control levels after 2 min. Another MoAb, IB4, directed against CD18, significantly inhibited ZAS-induced granulocyte extraction and associated cardiac effects. Thus, cardiac dysfunction occurs after activation of the complement cascade with zymosan resulting in extraction of granulocytes mediated by the CD18 adherence glycoprotein. Furthermore, intramyocardial retention of granulocytes appears necessary for the initial and full ZAS-induced cardiac dysfunction.

Anaphylatoxins↗
PubMed1990

In vivo and in vitro assessment of porcine neutrophil activation responses to chemoattractants: flow cytometric evidence for the selective absence of formyl peptide receptors.

Interest in the role that activated granulocytes play in C5a-induced myocardial ischemia prompted us to investigate and compare activation responses of pig and human neutrophils. The responses of Hypaque-Ficoll purified porcine (P-PMN) and human neutrophils (H-PMN) to stimulation with N-formyl-methionyl-leucyl-phenylalanine (FMLP), C5a, phorbol myristate acetate (PMA), and calcium ionophore A23187 (A23187) were compared by flow cytometrically measured changes in the cells' forward (FWD-SC) (a measure of shape/volume change) and right angle (90 degrees-SC) light scatter (a measure of secretion), and in the distribution of the membrane potential sensitive fluorescent probe di-O-C (3). FMLP, C5a, and Zymosan-activated serum (ZAS stimulated chemotaxis and FMLP vs. PMA-stimulated adherence to plastic were also compared. Unstimulated P-PMN had lower FWD-SC and 90 degrees-SC than H-PMN (39.4 +/- 1.4 vs. 48.4 +/- 2.0 P less than 0.05, and 32.7 +/- 2.7 vs. 52.4 +/- 1.5 units, P less than 0.005, for FWD-SC and 90 degrees-SC of P-PMN vs. H-PMN, respectively). P-PMN selectively failed to increase their FWD-SC upon stimulation with FMLP (0.0 +/- 0.5% vs. 26.1 +/- 6.8%, P-PMN vs. H-PMN), or decrease their 90 degrees-SC when treated with cytochalasin B + FMLP (secretion) (2.4 +/- 0.1% vs. -35.8 +/- 4.6% change in 90 degrees-SC, P-PMN vs. H-PMN), while responding comparably to C5a, PMA, and A23187. P-PMN failed to depolarize in response to FMLP but responded similarly to H-PMN when activated by C5a, A23187, and PMA. P-PMN's chemotactic response to FMLP was selectively absent since the cells responded well to purified pig C5a. FMLP stimulated significant increases in H-PMN adherence to bovine serum albumin-coated plastic (44.1 +/- 6.7% vs. 12.6 +/- 3.7%, FMLP vs. buffer, P less than 0.025), but failed to increase adherence of P-PMN above baseline 0.68 +/- 0.20% vs. 2.12 +/- 1.90%, FMLP vs. buffer, P greater than 0.05. PMA (100 ng/ml) stimulated comparable increases in adherence in both PMN types (48.6 +/- 5.2% vs. 58.7 +/- 4.9%, P-PMN vs. H-PMN, P less than 0.025). Binding studies using the fluoresceinated N-formyl peptide f-met-leu-phe-lysine-fluorescein-isothiocyanate (FMLPL-FITC) in the absence and presence of excess non-fluoresceinated FMLPL indicated that P-PMN lack specific binding sites for the N-formyl peptides.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Effects of dietary supplementation with eicosapentaenoic acid or gamma-linolenic acid on neutrophil phospholipid fatty acid composition and activation responses.

Previous data that alimentation with fish oil rich in eicosapentaenoic acid (EPA; 20:n-3) or vegetable oil rich in gamma-linolenic acid (GLA; 18:3n-6) can reduce symptoms of inflammatory skin disorders lead us to determine the effects of dietary supplements of oils rich in EPA or GLA on guinea pig (GP) neutrophil (PMN) membrane potential (delta gamma), secretion, and superoxide (O2-) responses. Weanling GPs were initially fed diets supplemented with olive oil (less than 0.1% EPA; less than 0.1% GLA) for 2 weeks, followed by a crossover by two sets of animals to diets supplemented with fish oil (19% EPA) or borage oil (25% GLA). At 4-week intervals, 12% sterile casein-elicited peritoneal neutrophils (PMN) were assessed for membrane polyunsaturated fatty acid (PUFA) profiles and FMLP-, LTB4-, and PMA-stimulated delta gamma changes, changes in flow cytometrically measured forward scatter (FWD-SC) (shape change), 90 degrees scatter (90 degrees -SC) in cytochalasin B-pretreated-PMN (secretion response), and superoxide responses, GP incorporated EPA and GLA (as the elongation product, dihomo-GLA or DGLA) into their PMN phospholipids by 4 weeks. The peritoneal PMN of all groups demonstrated broad resting FWD-SC and poor activation-related FWD-SC increases, suggesting in vivo activation. While secretion was comparable in the three groups in response to FMLP, there was a trend toward inhibition of LTB4-stimulated 90 degrees -SC loss in both fish and borage oil groups. This was significant only with borage oil (21.7 +/- 2.1 vs 15.3 +/- 1.2% loss of baseline 90 degrees -SC, olive vs borage: P = 0.03). PMN from borage- and fish oil-fed GPs showed a progressively lower O2- response to FMLP than the olive oil group (73.9 +/- 3.9 and 42.9 +/- 6.8% of olive oil response for borage and fish oils, respectively; P less than 0.005 and P less than 0.01, respectively, at 12 weeks), while PMA-stimulated O2- was inhibited only in the fish oil-fed group and only at 12 weeks (62.0 +/- 2.7% of control; P less than 0.025). We conclude that dietary supplementation with oils rich in PUFAs can modify PMN activation responses.

Animals↗
PubMed1990

Dietary supplementation with oils rich in (n-3) and (n-6) fatty acids influences in vivo levels of epidermal lipoxygenase products in guinea pigs.

Certain dietary oils may have therapeutic potential in the treatment of inflammatory skin disorders. Presumably, the fatty acid constituents of these dietary oils exert their effects by altering the levels of cutaneous eicosanoids. Prompted by this possibility, we investigated whether supplementation of guinea pig diets with fish oil [rich in 20:5(n-3)] or borage oil [rich in 18:3(n-6)] could significantly alter epidermal levels of eicosanoids compared with control animals supplemented with olive oil. After feeding periods of 4, 8 or 12 wk, the epidermis from the animals was analyzed for: 1) fatty acid composition of individual epidermal phospholipids, 2) levels of lipoxygenase products, and 3) levels of cyclooxygenase products (prostaglandins). Our results demonstrated that the animals supplemented with dietary fish oil had elevated levels of 20:5(n-3) in epidermal phospholipids and elevated epidermal levels of 15-hydroxyeicosapentaenoic acid (15-HEPE) [the 15-lipoxygenase product of 20:5(n-3)] compared with guinea pigs fed olive oil or borage oil. Similarly, the animals supplemented with dietary borage oil had elevated levels of 20:3(n-6) [the epidermal elongase product of 18:3(n-6)] in epidermal phospholipids and elevated epidermal levels of 15-hydroxyeicosatrienoic acid [15-HETrE, the epidermal 15-lipoxygenase product of 20:3(n-6)] compared with guinea pigs fed olive oil or fish body oil. There were no significant changes in epidermal levels of prostaglandins. Both 15-HEPE and 15-HETrE have been identified as possible anti-inflammatory metabolites, and their elevated presence in the epidermis of animals fed oils rich in 20:5(n-3) or 18:3(n-6) may provide a mechanism for the beneficial effects of these oils on inflammatory conditions.

Analysis of Variance↗
PubMed1990

Effects of low concentrations of arachidonic acid derived mediators on the membrane potential and respiratory burst responses of human neutrophils as assessed by flow cytometry.

Hypaque-Ficoll purified (95%) neutrophils (PMN) from normal healthy subjects were assessed for FMLP-elicited membrane potential (delta psi) responses and dichlorofluorescein (DCF) fluorescence (a measure of intracellular hydrogen peroxide production) using flow cytometry and appropriate fluorescent probes. Superoxide (O2) production was measured spectrophotometrically as the superoxide dismutase-inhibitable reduction of cytochrome C. The modulatory effects of dilute solutions of the arachidonic acid-derived inflammatory mediators LTB4, LTC4, LTD4, PGE1, PGE2 and PGF2 alpha (10(-9)-10(-5) M) were assessed in these systems. While LTB4 enhanced the proportion of cells depolarizing to the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (FMLP) 2-3x with a maximum effect in the 10(-9)-10(-8) M range, LTC4 and LTD4 showed no such enhancement except at high concentrations (10(-6) M). Unlike LTB4, LTC4 and LTD4 were unable to enhance FMLP mediated PMN O2 or DCF responses at any concentration tested, implying a divergence between the effects of the leukotrienes on membrane potential and oxidant responses. Pre-incubation of PMN with prostaglandins E1 or E2 led to a dose dependent inhibition of the proportion of depolarizing PMN in response to FMLP; PGF2 alpha did not show such an effect. The present data indicate that LTB4, in addition to being a powerful direct neutrophil activator, may act in a priming capacity by increasing the proportion of subsequently FMLP responsive cells, while PGE's inhibit. These modulatory effects appear relatively specific for LTB4 and the E-series prostaglandins.

Drug Interactions↗
PubMed1988

Patients with adult respiratory distress syndrome (ARDS) demonstrate in vivo neutrophil activation associated with diminished binding of neutrophil-specific monoclonal antibody 31D8.

Neutrophils (PMNs) from patients with adult respiratory distress syndrome (ARDS) were assessed for light scattering, membrane potential, and phagocytic responses using fluorescent probes and flow cytometry to evaluate individual cells. Qualitative and quantitative oxidant responses were measured by nitroblue tetrazolium (NBT) and cytochrome c reduction assays, respectively. The results were correlated with the proportion of cells binding the PMN subset-specific monoclonal antibody 31D8. Despite an increased forward scatter signal (4.3 +/- 1.6 vs. 1.3 +/- 1.1 ARDS vs. control, P = 0.041) and spontaneous NBT test (12.6 +/- 4.7% vs. 2.5 +/- 0.8% positive, ARDS vs. control, P = 0.033) indicating in vivo priming of ARDS PMNs, there were no significant differences between ARDS and control PMNs in assays of stimulated membrane potential, NBT, and O.2- production or phagocytosis. However, positive correlations between the degree of prestimulus forward light scatter and subsequent O.2- production to FMLP (r = 0.673, P = 0.006) and between the percentage of bands and the O.2- response to PMA (r = 0.660, P = 0.003), suggest that the great variability of the ARDS PMN functional responses may relate to varying degrees of in vivo cell priming and/or deactivation. ARDS PMNs demonstrated a significantly lower percentage of 31D8 positive cells (73.4 +/- 7.5% vs. 94.5 +/- 1.6%, P = 0.012) and a lower level of 31D8 staining when compared to normals (60.1 +/- 10.4% of control level, P = 0.001). The lower 31D8 expression did not directly correlate with any functional parameter tested or with the proportion of immature cells. However, patients receiving an intravenous PGE1 infusion demonstrated a significant increase in 31D8 staining relative to controls and inhibition of PMA-stimulated O.2- production. The data suggest that the function of PMNs from ARDS patients varies widely and reflects great in vivo variation in cell priming. While the mechanism responsible for the lowered expression of the 31D8 antigen and its apparent modulation by PGE1 is unknown, 31D8 may be an indirect marker for in vivo stress factors that regulate the preferential release of a structurally distinct PMN subset from the bone marrow.

Adult↗
PubMed1988

Enhancement of neutrophil function by granulocyte-macrophage colony-stimulating factor involves recruitment of a less responsive subpopulation.

Human granulocyte-macrophage colony-stimulating factor (GM-CSF) enhances numerous functions of mature neutrophils (PMN) including phagocytosis, superoxide responses to chemotaxins, antibody-dependent cellular cytotoxicity, and expression of complement receptors. A central question concerns whether the mechanism of enhancement involves quantitative increases in the response of all cells v subpopulation recruitment. The effects of GM-CSF on individual cell light scatter changes, membrane potential, and oxidant responses induced by the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (FMLP) were assessed by flow cytometry and by scoring individual cells for nitroblue tetrazolium dye (NBT) reduction. GM-CSF produced a dose- and time-dependent shift in forward light scatter that was very similar in character to that seen with FMLP or leukotriene B4 stimulation. Although not capable of depolarizing the cells directly, GM-CSF primed PMNs for enhanced membrane potential responses to FMLP by significantly increasing the proportion of depolarizing cells when compared with diluent-treated controls after a 60-minute incubation at 37 degrees C (79.4% +/- 3.4% v 29.5% +/- 4.7% GM-CSF v diluent, mean +/- SE, P less than .005, n = 11). Subpopulation recruitment by GM-CSF treatment was also demonstrated by the FMLP-elicited NBT test. Taken together, these results indicate that GM-CSF can modulate the function of mature PMN by enhancing the proportion of responsive cells.

Colony-Stimulating Factors↗
PubMed1987

Prostaglandin E1 inhibits N-formyl-methionyl-leucyl-phenylalanine-mediated depolarization responses by decreasing the proportion of responsive cells without affecting chemotaxin-induced forward light scatter changes.

Hypaque-Ficoll-purified human polymorphonuclear neutrophils (PMN) equilibrated with the membrane potential-sensitive probe 3,3'dipentyloxacarbocyanine [di-O-C(5)(3)] were incubated with buffer or cytochalasin B (cyto B) followed by incubation with prostaglandin E1 (PGE1) (0 to 10(-5) M) for 5 min at 37 degrees C. The cells were then stimulated with N-formyl-methionyl-leucyl-phenylalanine (FMLP) (0 to 10(-5) M). Changes in forward light scatter (FWD-SC), 90 degrees scatter (90 degrees -SC), and fluorescence intensity were measured by flow cytometry to determine the effects of PGE1 on FMLP-induced shape change, secretion, and membrane potential responses, respectively. In other experiments, the effects of PGE1 preincubation on FMLP +/- cyto B and phorbol myristate acetate-induced (O2) production were measured by superoxide dismutase-inhibitable cyto c reduction. PGE1 had no direct effects on the FWD-SC, 90 degrees-SC, or resting potential fluorescence of unstimulated or cyto B-pretreated PMN. PGE1 produced a dose-dependent inhibition of the proportion of depolarizing PMN in response to FMLP, which was maximal at 10(-6) M (42.1 +/- 6.9% inhibition, p less than 0.005), but was apparent at 10(-8) M. The PGE1-induced inhibition was maximal after 30 sec of incubation at 37 degrees C and was caused by a decrease in the maximal percentage of depolarizing PMN without a significant change in the FMLP dose-response curve (Km = 2.43 vs 3.62 X 10(-8) M, control vs PGE1-treated) or an inhibition in the degree of depolarization by the responding subpopulation. PGE1 also inhibited the loss of 90 degrees-SC induced by FMLP in cyto B-pretreated cells (secretion response) (46.2 +/- 16.5% inhibition of the maximal 90 degrees-SC loss, n = 5, p less than 0.005), but did not affect the increase in FWD-SC seen with FMLP-induced PMN activation or the ability of cyto B to recruit more PMN to depolarize. PGE1 also inhibited FMLP +/- cyto B-induced O2 production in a dose-dependent fashion; phorbol myristate acetate-induced O2 production was also slightly inhibited, but only at high PGE1 concentrations. The data indicate that PGE1 inhibits FMLP-induced cell activation by a mechanism that involves a step distal to the recruitment of unresponsive PMN by cyto B, and that PGE1 is capable of inhibiting depolarization responses without affecting FMLP-induced shape change, providing more support for a dissociation between the two activation pathways.

Alprostadil↗
PubMed1986

Modulation of the heterogeneous membrane potential response of neutrophils to N-formyl-methionyl-leucyl-phenylalanine (FMLP) by leukotriene B4: evidence for cell recruitment.

Individual human neutrophils (PMN) isolated by Hypaque-Ficoll gradient sedimentation, dextran sedimentation, or buffy coat preparation were assessed for the effects of leukotriene B4 (5S,12R dihydroxy 6,14-cis-8, 10 trans eicosatetraenoic acid (LTB4)-pretreatment on N-formylmethionyl-leucyl-phenylalanine (FMLP)-mediated membrane potential or oxidative responses by using flow cytometry and a lipophilic probe of membrane potential (di-pentyl-oxacarbocyanine, di-O-C(5)3), or the nitroblue tetrazolium dye (NBT) reduction test, respectively. Although exposure to LTB4 (10(-7) M) had no effect on the membrane potential of resting PMN and little effect on oxidant production, pretreating PMN with LTB4 followed by FMLP (10(-6) M) demonstrated a significant enhancement in the proportion of depolarizing PMN over that seen with FMLP alone (p = 0.0014, N = 9). This recruitment of previously unresponsive cells by LTB4 was dose and time dependent, with the maximal relative increase in the proportion of depolarizing cells occurring at LTB4 concentrations of 10(-8) to 10(-7) M and within 1 min of LTB4 addition. The recruitment effect persisted despite vigorous washing of the cells. LTB4 also increased the proportion of NBT-positive PMN in response to FMLP. Although LTB4 alone did not depolarize PMN it did induce a light scatter shift indicative of cell activation. 3H-FMLP binding studied at 0 degree C comparing buffer and LTB4-treated PMN indicated no significant change in the number or affinity of FMLP binding. The data provide evidence for the recruitment of a greater proportion of cells into a FMLP-responsive state as a mechanism for the enhanced functional response of PMN pretreated with LTB4, as well as for a dissociation of the membrane potential and light scattering responses of cells to this pro-inflammatory LT. The mechanism of recruitment remains unclear, but it most likely involves the modulation of a post-FMLP binding step.

Chemotaxis, Leukocyte↗
PubMed1986

PMN heterogeneity: long-term stability of fluorescent membrane potential responses to the chemoattractant N-formyl-methionyl-leucyl-phenylalanine in healthy adults and correlation with respiratory burst activity.

Polymorphonuclear neutrophils (PMNs) were isolated from 24 healthy adults 20 to 61 years of age and the proportion of cells that demonstrated depolarization responses to the synthetic chemotaxin N-formyl-methionyl-leucyl-phenylalanine (FMLP) were enumerated using the lipophilic fluorescent cyanine dye 3,3'-di-pentyl-oxacarbocyanine [di-O-C(5)(3)] and flow cytometry. The membrane potential responses were correlated to the cells' respiratory burst capabilities as measured by nitroblue tetrazolium (NBT) reduction and/or superoxide production in response to FMLP; 40.2% +/- 15.1% (mean +/- SD) of cells depolarized to FMLP. The mean SE for duplicate determinations 1 hour apart was 3.8% (range 0.4% to 13.6%, n = 15). There was no correlation between the percentage of depolarizing PMNs and the yield of cells, the percentage of immature cells, or the circulating WBC count. There was no difference in the average age of men (34.9 +/- 9.9 years, n = 11) v women (33.8 +/- 8.5, n = 13) (mean +/- SD) studied, or in the percentage of depolarizing PMNs when men and women were compared (42.2 +/- 10.6% v 43.1 +/- 13.3%, respectively). However, there was a significant increase in the percentage of depolarizing PMNs with increasing age of women (r = .61, P less than .025) but not men (r = .03, P greater than .05). Analysis of variance revealed significantly greater person-to-person variability in the membrane potential response than in day-to-day variability in the same person (P less than .0005). The percentage of depolarizing PMNs in response to FMLP was significantly correlated with the percentage of NBT-positive cells from both purified PMNs and from whole blood (r = .849, P less than .0005, r = .857, P less than .05, respectively), and with the amount of superoxide produced, expressed as a percentage of that amount produced by cytochalasin B (cyto-B)-pretreated cells (r = .565, P less than .01). The data indicate that PMNs from healthy adults demonstrate a heterogeneous membrane potential response to the chemotaxin FMLP that correlates with the cells' oxidative responsiveness and that intersubject differences can be detected. In addition, the proportion of responsive PMNs increases with increasing age in women.

Adult↗