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PubMed2002

The CXC chemokine NAP-2 mediates differential heterologous desensitization of neutrophil effector functions elicited by platelet-activating factor.

During early inflammation, the chemoattractants neutrophil-activating peptide-2 (NAP-2), platelet-activating factor (PAF), and complement component C5a are rapidly generated within the vasculature and potently induce effector functions in neutrophils, such as chemotaxis and degranulation. We investigated whether these mediators would cross-desensitize each other's activities on isolated neutrophils. We demonstrate that NAP-2 and C5a desensitize degranulation of neutrophils in response to PAF. However, whereas C5a-mediated desensitization correlated with the downregulation of PAF binding sites on neutrophils, NAP-2 did not regulate PAF receptors, nor did it modulate their calcium signaling. In further contrast to C5a, which desensitized PAF-induced neutrophil chemotaxis, NAP-2 did not affect the chemotatic response to PAF. These observations indicate that NAP-2 mediates selective desensitization of PAF-induced neutrophil degranulation by a mechanism downstream from PAF receptors, still allowing migration toward PAF. Thus, a role for NAP-2 may be to limit PAF-dependent vascular tissue damage by preventing degranulation of neutrophils without affecting their migration into the inflamed tissue.

Blood Coagulation Factors↗

PubMed2000

Functional heterogeneity of rat hepatic and alveolar macrophages: effects of chronic ethanol administration.

Chronic ethanol consumption is associated with increased incidence of hepatic and pulmonary infections. To determine if this is correlated with altered macrophage activity, we analyzed the functional properties of cells isolated sequentially from the liver and lung of rats fed a liquid diet containing ethanol (35% of calories) or malto-dextrin control for 9-12 weeks. Hepatic and alveolar macrophages from control animals were found to exhibit distinct morphologic and functional properties. Thus, hepatic macrophages were highly vacuolated and appeared larger and more irregular in shape than alveolar macrophages. These cells also displayed greater phagocytic activity and random migration. In contrast, lung macrophages produced more superoxide anion and nitric oxide, and exhibited enhanced chemotactic activity toward the complement fragment C5a. Whereas administration of ethanol to rats for 9-12 weeks resulted in decreased chemotaxis and superoxide anion production by alveolar macrophages, cell adhesion molecule expression was reduced in hepatic macrophages. Nitric oxide production and inducible nitric oxide synthase protein expression were decreased in both macrophage populations. These effects were not observed after 3-6 weeks of ethanol administration to rats. Our results suggest that changes in macrophage functioning may play a role in decreased host defense following chronic ethanol exposure.

Animals↗

PubMed1999

Adenosine A3 receptors on human eosinophils mediate inhibition of degranulation and superoxide anion release.

The role of adenosine A3 receptors on human eosinophil degranulation and superoxide anion (O2-) release was studied in vitro using the complement fragment C5a as the main stimulus and employing a number of selective agonists and antagonists. In the presence of cytochalasin B (CB), C5a induced a dose-dependent release of the granular eosinophil peroxidase (EPO), but not O2-, whereas in the absence of CB O2- , but not EPO, was released. C5a-induced EPO release was inhibited dose-dependently by the selective A3 agonist N6-(3-iodobenzyl)-5'-N-methylcarbamoyladenosine (IB-MECA) and to a lesser extent by the less-selective N6-2-(4-amino-3-iodophenyl) ethyladenosine (APNEA). The IC50 (95% CI) for IB-MECA was 6.8 microM (3.1-12.0 microM). At concentrations up to 100 microM, neither adenosine nor the selective A1 agonist N-cyclopentyladenosine (CPA) and the selective A2 agonist 2-[[2-[4-(2-carboxyethyl)phenyl]ethyl]amino]-N-ethylcarboxamidoadenosine (CGS 21680) had any significant effect. The inhibitory effect of IB-MECA was almost completely abolished by pre-treatment with 1 microM of the selective A3 antagonist 9-chloro-2-(2-furyl)-5-phenylactylamino[1,2,4]triazolo[1,5-c]quina zoline (MRS 1220), but not the selective A1 antagonist 1,3-dipropyly-8-cyclopentylxanthine (DPCPX) or the selective A2 antagonist 3,7-dimethyl-1-propargylxanthine (DMPX). IB-MECA also significantly inhibited C5a-induced O2- release with IC50 (95% CI) of 9.5 microM (4.6-13.1 microM) whereas adenosine and the A1 agonist CPA potentiated this effect at low concentrations. The potentiation appeared to be a result of their direct O2- release from these cells, probably mediated via A1 receptors. The inhibition by IB-MECA was selectively reversed by MRS 1220. These results show that the A3 receptors on human eosinophils mediate inhibition of both degranulation and O2- release and suggest a therapeutic potential for A3 agonists in diseases such as asthma in which activated eosinophils are involved.

Cell Degranulation↗

PubMed1994

Effects of alpha-1 acid glycoprotein on human polymorphonuclear neutrophils: influence of glycan microheterogeneity.

The biological functions of alpha-1 acid glycoprotein (AGP) are poorly understood but appear to depend on glycan microheterogeneity. Variations of AGP glycan structure (in terms of concanavalin A (ConA) reactivity) have been observed during the inflammatory process. We studied these modifications in AGP from patients with chronic renal impairment and investigated the effects of AGP microheterogeneity on healthy polymorphonuclear leukocyte (PMN) chemotaxis and oxidative metabolism. AGP was extracted by a two-step procedure from sera from ten patients with various degrees of renal impairment, selected according to AGP glycan heterogeneity determined by crossed immunoaffinity electrophoresis with ConA. AGP (0.5 g/l) significantly inhibited the chemotactic response of PMN to formyl-methionyl-leucyl-phenylalanine (10(-7) mol/l) and complement fraction C5a, regardless of ConA reactivity. AGP also inhibited superoxide anion generation in response to phorbol myristate acetate (10(-7) mol/l). After stimulation by opsonized zymosan (1 g/l), the effect of AGP appeared to depend on its glycan structure (r = 0.70, P < 0.05), decreasing with ConA non-reactivity. These data suggest that AGP can down-regulate neutrophil responsiveness, an effect that depends in part on its glycan microheterogeneity. Alterations of AGP microheterogeneity in various pathological states, particularly renal failure, may be related to the inflammatory process.

Adult↗

PubMed1993

Upregulation of formyl-peptide and interleukin-8-induced eosinophil chemotaxis in patients with allergic asthma.

BACKGROUND: The cytokine granulocyte-macrophage colony-stimulating factors, interleukin-3 and interleukin-5, are important modulators of eosinophilia and eosinophil function. In particular, eosinophil chemotaxis is very sensitive to cytokine priming. METHODS: We evaluated chemotactic responses of eosinophils from patients with allergic asthma. These cells exhibited a primed phenotype as deduced from enhanced responses toward formyl-methionyl-leucyl-phenylalanine and platelet-activating factor and a decreased responsiveness toward granulocyte-macrophage colony-stimulating factor. Bronchoprovocation of patients with allergic asthma with allergen was performed as a possible means to enhance in vivo priming. RESULTS: Indeed, eosinophils isolated 3 hours after allergen challenge exhibited a more pronounced primed phenotype, which was reflected by an induction of responsiveness towards interleukin-8. Eosinophil responses induced by platelet-activating factor, formyl-methionyl-leucyl-phenylalanine, complement fragment C5a, interleukin-3, interleukin-5, and granulocyte-macrophage colony-stimulating factor were not significantly altered after allergen challenge. CONCLUSION: These data provide further evidence that eosinophils are already primed in the peripheral blood of individuals with allergic asthma. This is most likely due to the presence of circulating cytokines in the peripheral blood of those individuals. This in vivo priming results in selective upregulation and downregulation of responses toward various chemotaxins, which may be released in the lungs during allergic inflammation.

Adult↗

PubMed1982

Defects of serum chemoattraction and polymorphonuclear leucocyte movement in patients with primary hepatocellular carcinoma.

Movement of polymorphonuclear leucocytes to the site of tumour cells may be an important stage in host defences against tumours in a variety of organs. In this study, sera from 29 of 30 patients with primary hepatocellular carcinoma had reduced ability to stimulate the movement in vitro of normal polymorphonuclear leucocytes. The serum defect was more severe in 11 patients with underlying cirrhosis but was not related to abnormalities of tests of liver function, levels of serum alphafetoprotein, or deficiency of complement factors C3 and C5. Serial studies showed that the defect was persistent and progressive in patients in whom the tumour did not respond to treatment. In 35% of patients, mainly those with cirrhosis, the sera contained antagonists to normal serum chemotactic factors which were heat stable and dialysable, but could be distinguished by their effect on complement factor C5a. A heat labile dialysable antagonist(s) was found in sera from 28% of the patients (mainly those without cirrhosis) which antagonized the movement of normal polymorphonuclear leucocytes (cell directed antagonism). In addition to these serum defects, polymorphonuclear leucocytes from two of seven patients studied had reduced movement which was not related to the presence in the serum of cell directed antagonists. These serum and cellular defects have not been reported previously in patients with primary hepatocellular carcinoma, and could compromise the body's defences against the tumour.

Adolescent↗

PubMed1991

Development of fish peritoneal macrophages as a model for higher vertebrates in immunotoxicological studies. I. Characterization of trout macrophage morphological, functional, and biochemical properties.

The immune defense mechanisms of fish are not as well characterized as those of mammals but seem to be related and similarly competent. Because of this, there is an increased interest in the immune responses of fish as models for higher vertebrates in immunotoxicological studies. Prior to such studies, baseline criteria for specific components of the immune response needed to be established. For this study, we have examined trout macrophage morphology using light and scanning electron microscopy, phagocytic activity, random and stimulus-directed migration, and superoxide anion radical (O2-) production for resident and lipopolysacharide (LPS) or Aeromonas salmonicidae-elicited rainbow trout (Oncorhynchus mykiss) peritoneal macrophages (M phi). Following peritoneal lavage, greater than 89% of the cells were M phi as determined by differential counts and nonspecific esterase staining. Immunization with LPS and A. salmonicidae increased M phi number approximately 5 and 13-fold, respectively, and overall size. Trout M phi were phagocytically active engulfing serum opsonized latex particles and were mobile, migrating both randomly and in a directed fashion towards formyl-methionine-L-leucine-L-phenylalanine (FMLP) and trout serum-derived complement fragment C5a. Concentrations of FMLP (100 nM) and C5a (0.01-1%) effective for attracting trout M phi are the same as those used to attract rabbit M phi. Resident trout M phi produced negligable quantities of .O2- following stimulation with 1 micrograms/ml phorbol myristate acetate; Aeromonas-elicited M phi produced .O2- in a time-dependent manner which peaked after 60 min at 2.9 nmol per 2 x 10(5) cells and then declined. The results of this study provide a data base for future toxicological studies with trout peritoneal M phi and indicate the usefulness of this system for immunotoxicological studies.

Aeromonas↗

PubMed1997

Clinical characterization of Dicea a new cellulose membrane for haemodialysis.

A prospective randomised clinical study comparing the functional performance and biocompatibility of a new cellulose diacetate variant (Dicea) in which the degree of hydroxyl group substitution differs, with cellulose diacetate and low flux polysulfone incorporated into commercially produced hollow fiber hemodialysers with a surface area 1.5-1.6 m2 has been undertaken. All dialysers studied demonstrated clinically acceptable performance in terms of their small molecular removal characteristics, with minor statistical but not clinical differences. Use of both cellulose diacetate membranes but not low flux polysulfone resulted in a reduction in plasma beta(2) microglobulin levels. The membranes were impermeable to albumin, but showed some permeability to low molecular weight proteins. The average protein recovery from the dialysis fluid was 3105 mg for Dicea, 2913 mg for cellulose diacetate and 2842 mg for low flux polysulfone. For Dicea the white cell count by 15 minutes had declined to 68% of pre treatment value, compared with 59% and 86% for cellulose diacetate and low flux polysulfone. The differences between Dicea and cellulose diacetate were not significant, but both cellulose based membranes differed from low flux polysulfone (p = 0.0015). There was a strong evidence of differences between the membranes in respect of C5a and C5b-9 generation (p = 0.0001) but not for C3a (p = 0.16) furthermore the levels of C5b-9 generated during dialysis also showed a significant positive correlation compared to C5a for all membranes. (Pearson's correlation coefficient = 0.856, p = 0.0001). It is concluded that the two cellulose diacetate membranes are not identical, with the differences observed being a consequence of the degree of acetyl substitution, resulting in alteration of membrane structure and the method of sterilization. The clinical significance of these differences are difficult to characterize but the modification of the cellulose structure appears to be a promising method to improve the biocompatibility of cellulose membranes. The improved biocompatibility offered by this method still falls short of that achieved with low flux synthetic membranes such as Fresenius Polysulfone.

Adult↗

PubMed1997

Circulating promyelocytes and low levels of CD16 expression on polymorphonuclear leukocytes accompany early-onset periodontitis.

Early-onset periodontitis (EOP) is characterized by rapidly progressive alveolar bone loss, chemotactic defects of neutrophils, and significant familial aggregation. We found immature myeloid lineage cells, defined as promyelocytes, in the peripheral blood in patients with EOP. A hematological examination of peripheral blood cells showed normal reference values regarding cell proportions. Flow cytometry revealed significantly lower expression of CD16, a glycosylphosphatidylinositol (GPI)-anchored protein, on peripheral neutrophils in patients compared with those in age- and sex-matched healthy controls, whereas the levels of CD11a and CD11b expression were similar. The chemotactic response of neutrophils was lower toward not only formyl-methionyl-leucyl-phenylalanine but also complement fragment C5a than that of healthy controls. The expression of another GPI-anchored protein, CD14, was equally expressed by controls and patients. Therefore, the low level of CD16 expression was not due to the incomplete synthesis of the GPI anchor. GPI anchors of CD16 on neutrophils from controls and patients were both partially resistant to phosphatidylinositol-specific phospholipase C. The presence of promyelocytes in peripheral blood, low expression of CD16, and low chemotactic response of neutrophils suggest that patients with EOP have an abnormal maturation system in myeloid lineage cells in the bone marrow, which may be associated with the onset and course of EOP.

Adult↗

PubMed1984

Inhibition of human neutrophil secondary granule discharge by antiinflammatory agents.

Human neutrophil cobalamin binding protein (NCBP) is located exclusively in the neutrophil secondary granules. The soluble stimuli formlymethionyl-leucyl-phenylalanine and the low-molecular-weight complement fragment C5a both promote the dose-dependent release of NCBP from cytochalasin B-treated neutrophils in vitro. The extracellular discharge of NCBP induced by higher secretagogue is inhibited by prior exposure of neutrophils to the corticosteroids hydrocortisone and methylprednisolone and the nonsteroidal antiinflammatory agents indomethacin and ibuprofen. The four antiinflammatory agents function as competitive antagonists of neutrophil secondary granule discharge with a site of action at or near the cell surface. These findings support the hypothesis that antiinflammatory agents prevent neutrophil activation in vitro by inhibition of stimulus-receptor coupling. The significance of these observations with regard to the in vivo actions of these agents remains uncertain, however.

Anti-Inflammatory Agents↗

PubMed1990

Type 1 astrocytes and oligodendrocyte-type 2 astrocyte glial progenitors migrate toward distinct molecules.

During central nervous system (CNS) development, glial precursors proliferate in subventricular zones and then migrate throughout the CNS to adopt their final destinations and differentiate into various types of mature glial cells. Although several growth factors promoting the proliferation and/or differentiation of glial precursors have been identified, very little is known about the nature of signals that guide glial cell migration in the CNS. Therefore, we have investigated whether polypeptide growth factors and/or extracellular matrix molecules may mediate the migration of two major glial cell types, type 1 astrocytes and oligodendrocyte-type 2 astrocyte (O-2A) progenitor cells. We show that, in a microchemotaxis chamber assay, type 1 astrocytes move toward laminin and complement-derived C5a. Astrocyte migration toward laminin is inhibited by a laminin-specific pentapeptide, YIGSR-NH2. In contrast, O-2A progenitors migrate toward platelet-derived growth factor (PDGF), which also functions as a mitogen for these cells. Using a new method to simultaneously assay migration and DNA synthesis, we also demonstrate that O-2A progenitors can migrate toward PDGF even when DNA replication is inhibited with an antimitotic agent. Thus, migration of different types of glial cells can be induced in vitro by specific signaling molecules, which are present in the developing brain and may stimulate migration of glial cells prior to CNS myelination.

Amino Acid Sequence↗

PubMed2003

Inflammatory response of a new synthetic dialyzer membrane. A randomised cross-over comparison between polysulfone and helixone.

Hemodialysis patients suffer from chronic inflammation due to intradialytic contact of blood with artificial materials. The FX 60 dialyzer which belongs to the new FX-class series of dialyzers is composed of the new membrane Helixone. This membrane is derived from the original Fresenius Polysulfone membrane. The FX-class design is based on modified geometry of fibres and housing and has resulted in a new dialyzer with improved efficiency, safety and ease of handling compared to the F series (F 60S) dialyzer. The aim of the study was to investigate whether the biocompatibility pattern in terms of inflammatory parameters of the new type of polysulfone dialyzer has changed compared to the standard. A clinical in vivo study was conducted to compare the intradialytic inflammatory response of the two dialyzers, FX 60 and F 60S. Eight chronic dialysis patients were selected for the study: mean age 65.5 +/- 15.5 years, mean time on dialysis 100 +/- 95 months. The randomized cross-over study involved a treatment period of 2 weeks (total 6 sessions), one week with each dialyzer, starting with one or the other according to the randomization scheme. Blood samples were taken at 0 (T0), 15, 60, and 240 minutes to evaluate white blood cell (WBC) count, complement factor C5a, leukocyte elastase, soluble intercellular adhesion molecule 1 (sICAM-1), platelet count, C-reactive protein (CRP). At 15 min, WBC count showed a comparably, low decrease for both dialyzers: -7.6% for FX 60 versus -6.6% for F 60S, p=not significant (ns). At the same time the C5a concentration decreased from 15.0 +/- 7.5 ng/ml to 13.5 +/- 6.7 ng/ml (p=ns) for FX 60, and from 15.1 +/- 12.5 ng/ml to 14.9 +/- 25.0 ng/ml for F 60S (p=ns). The elastase concentration progressively increased over time with no statistical difference between the two dialyzers. The levels of sICAM-1, CRP, and platelet count were similar at each time point for both dialyzers, varying around the baseline values (p=ns). No significant difference emerged in terms of inflammatory response between the two dialyzers, hemo demonstrating that the biocompatibility of the F-series was maintained in the FX-class series of dialyzers and is independent of design factors.

Aged↗

PubMed1984

A role for sulfhydryl groups in granulocyte aggregation.

Polymorphonuclear leukocytes (PMN) stimulated by high concentrations of the complement component C5A form cellular aggregates, and both the rate and degree of aggregation are influenced by changes in the PMN plasma membrane and cytoskeleton. Since sulfhydryls are important constituents of the plasma membrane and cytoskeleton, we investigated the effect of agents that oxidize and bind sulfhydryls on C5A-induced aggregation. PMN incubated with diamide, a nonspecific sulfhydryl-oxidizing agent, had a marked increase in their aggregation response to C5A. Tertiary butyl hydroperoxide (BHP), which reacts specifically with the soluble sulfhydryl glutathione (GSH), had no effect on aggregation. The enhancement of PMN aggregation by diamide, but not BHP, suggested that oxidation of non-GSH sulfhydryls contributes to the aggregation response. To test the requirement for sulfhydryls in PMN aggregation, PMN were treated with the sulfhydryl-binding agent N-ethylmaleimide (NEM). NEM markedly impaired aggregation without affecting resting or methylene blue-stimulated [14C]-L-glucose oxidation of the granulocytes. P-chloromercuriphenyl sulfonic acid (PCMPSA), an external sulfhydryl-binding agent, had no effect on aggregation. These studies suggest that cellular sulfhydryls are required for optimal PMN aggregation and that oxidation of these sulfhydryls may be one of the biochemical changes that contributes to aggregation.

Cell Aggregation↗

PubMed1986

Neutrophil-dependent mediation of microvascular permeability.

Macromolecular extravasation induced by the chemoattractants N-formyl-methionylleucylphenylalanine (FMLP), complement fragment C5a, and leukotriene B4 (LTB4) has been reported to be neutrophil dependent. A review of experimental evidence argues against mechanical disruption of the endothelial barrier as a likely mechanism for enhanced microvascular permeability. Other proposed mechanisms attribute macromolecular efflux to extracellular liberation of granule constituents or granule-independent neutrophil release products (e.g., oxygen radicals) that can undermine vascular integrity by direct or indirect actions on endothelial cells or other components of vascular walls (glycocalyx, basement membrane). The cytotoxic potential of neutrophil-release products on endothelial cells prompts consideration of a transcellular pathway for macromolecular transport. Further studies are needed to clarify the precise nature of endothelial injury and its resolution to better understand the physiology behind the transient effects of these mediators on vascular permeability.

Animals↗

PubMed2000

Differential ability of exogenous chemotactic agents to disrupt transendothelial migration of flowing neutrophils.

Neutrophils migrate through endothelium using an ordered sequence of adhesive interactions and activating signals. To investigate the consequences of disruption of this sequence, we characterized adhesion and migration of neutrophils perfused over HUVEC that had been treated with TNF-alpha for 4 h and evaluated changes caused by exogenously added chemotactic agents. When HUVEC were treated with 2 U/ml TNF, flowing neutrophils adhered, with the majority rolling and relatively few migrating through the monolayer. If fMLP, IL-8, zymosan-activated plasma (a source of activated complement factor C5a), epithelial cell-derived neutrophil-activating peptide (ENA-78), or growth-regulating oncogene, GRO-alpha, was perfused over these neutrophils, they stopped rolling and rapidly migrated over the monolayer, but did not penetrate it. When HUVEC were treated with 100 U/ml TNF, the majority of adherent neutrophils transmigrated. If neutrophils were treated with fMLP, IL-8, C5a, ENA-78, or GRO-alpha just before perfusion over this HUVEC, transmigration, but not adhesion, was abolished. However, when platelet-activating factor was used to activate neutrophils, migration through HUVEC treated with 100 U/ml TNF was not impaired, and migration through HUVEC treated with 2 U/ml TNF was actually increased. Transmigration required ligation of CXC chemokine receptor-2 on neutrophils, and differential desensitization of this receptor (e.g., by fMLP but not platelet-activating factor) may explain the pattern of disruption of migration. Thus, transmigration may require presentation of the correct activators in the correct sequence, and inappropriate activation (e.g., by systemic activators) could cause pathological accumulation of neutrophils in the vessel lumen.

Cell Adhesion↗

PubMed1993

Synergic in vitro effects of interleukin-2 and tau-interferon on the migration of blood monocytes from control subjects and patients with lung cancer.

BACKGROUND: Macrophages can play a major role against cancer by exerting their cytotoxic activity against tumor cells. The presence of macrophages in tumor stroma is related to the recruitment of circulating blood monocytes through the release of chemotactic factors by cancer cells. However, fewer blood monocytes from patients with cancer, such as lung cancer, migrate from in vivo and in vitro, compared with blood monocytes control subjects. METHODS: Two cytokines, interleukin-2 (IL-2) and tau-interferon (tau-INF), proposed in the treatment of cancer, were tested for their ability to modulate the migratory response in modified Boyden chemotactic chambers of blood monocytes obtained from control subjects and patients with lung cancer in the presence of two chemotactic factors: N-formylmethionyl-leucyl-phenylalanine and complement fraction C5a (C5a). RESULTS: Incubation with IL-2 and tau-INF resulted in a dose-dependent depression of the migration of blood monocytes from control subjects and patients with lung cancer. IL-2 depression was induced by IL-2 concentrations of 10(5) units/ml, and tau-IFN effects were measured for concentrations of 100 mu/ml. Furthermore, when low concentrations of IL-2 were tested in combination with low concentrations of tau-IFN, dose-dependent depression of blood monocyte migration occurred. CONCLUSIONS: Dose-dependent depression of blood monocyte migration may modulate the inflammatory component of tumor stroma in patients with lung cancer treated with these cytokines. It may also explain, in part, the high incidence of infections in patients treated with IL-2.

Adenocarcinoma↗

PubMed1992

Interactions of granulocyte-macrophage colony-stimulating factor (CSF), granulocyte CSF, and tumor necrosis factor alpha in the priming of the neutrophil respiratory burst.

Exposure of neutrophils to a range of cytokines augments their response to subsequent agonist-induced activation of the respiratory burst. We have examined the effects of several of these factors, both singly and in combination, on the priming of f-met-leu-phe (FMLP) and complement C5a-stimulated neutrophil H2O2 production, using a whole blood flow cytometric assay designed to minimize artefactual activation. Both granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor alpha (TNF alpha) produced a similar degree of priming of the FMLP-stimulated burst in vitro (558% +/- 86%, n = 41, and 581% +/- 95%, n = 21, of the response seen with FMLP alone, respectively), but with markedly different kinetics (half-maximal response 20 minutes and 7 minutes, respectively). Preincubation with granulocyte colony-stimulating factor (G-CSF) alone caused only modest priming (202% +/- 39%, n = 14). Priming with cytokine combinations of the FMLP-stimulated burst showed that the combinations of G-CSF and TNF alpha and GM-CSF and TNF alpha are highly synergistic, with recruitment of neutrophils unresponsive to priming by single agents. Priming with the combination of GM-CSF and G-CSF was not significantly different to priming with GM-CSF alone. Similar results were obtained using C5a as the respiratory burst stimulus. Significant priming of the FMLP-stimulated respiratory burst was seen in vivo in patients receiving an infusion of GM-CSF (332% +/- 50% of preinfusion response to FMLP, P less than .005, n = 8). Priming was also seen in patients receiving G-CSF (152% +/- 58%, n = 5), although this did not reach conventional significance levels (.05 less than P less than .1). Although GM-CSF infusion caused priming in vivo, this was 48% less than predicted by preinfusion in vitro responses. This result was not due to inadequate GM-CSF levels as addition of further GM-CSF ex vivo did not correct the response. However, these neutrophils were still able to respond appropriately to ex vivo priming with TNF alpha, with a doubling in H2O2 production.

Complement C5a↗

PubMed1992

Inflammatory response to acute inhalation of endotoxin in asthmatic patients.

Inhalation of 20 micrograms endotoxins (from the membrane of Gram-negative bacteria) has been reported to induce a bronchial obstructive response in asthmatic subjects. The aim of the present study was to evaluate in asthmatic patients the possibility of an inflammatory response to inhaled endotoxins. Eight patients with mild asthma were submitted to bronchial challenge tests, in a single-blind trial, on Day 1 with control solution and on Day 7 with 20 micrograms endotoxin of Escherichia coli (026:B6). Local inflammatory response was indirectly evaluated by the degree of bronchial hyperresponsiveness (BHR) expressed as PD20 FEV1 histamine (the dose of histamine inducing a 20% decrease in FEV1) at 0, 6, 24, and 48 h and 7 days. Systemic inflammation was investigated by sequential blood determinations of total (and differential) white cells, complement anaphylatoxin C5a, interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and C-reactive protein (CRP). A significant (p < 0.01) bronchial obstructive response was demonstrable 45 min after lipopolysaccharide (LPS) inhalation, lasting 5 h. Comparing the level of BHR after control inhalation, a significant (p < 0.05) increase in BHR was shown 6 h after LPS, partially normalized at 24 and 48 h. A short peak in TNF-alpha at 60 min (p < 0.05) and an increase in total white blood cells (p < 0.01) and neutrophil polymorphonuclear neutrophils at 360 min (p < 0.05) and of CRP at 24 and 48 h (p < 0.05 and p < 0.01) were significant. The other blood parameters did not change significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗