Enhancement of neutrophils function as a result of prior exposure to chemotactic factor

Does linezolid modulate lung innate immunity in a murine model of methicillin-resistant Staphylococcus aureus pneumonia?

OBJECTIVES

Methicillin-resistant Staphylococcus aureus is an important cause of mortality among nosocomial infections. Recent investigations suggest that linezolid is superior to vancomycin in achieving clinical cure in patients with nosocomial pneumonia. We hypothesized that linezolid may exhibit anti-inflammatory properties in vivo model of pneumonia.

DESIGN

Prospective interventional study.

SETTING

University affiliated laboratory.

SUBJECTS

BALB/c mice.

INTERVENTIONS

Three groups of BALB/c mice were inoculated with methicillin-resistant S. aureus American Type Culture Collection 33,591 to induce pneumonia. Each group (n = 6) underwent bronchoalveolar lavage at 24 hrs, 48 hrs, and 72 hrs after inoculation after treatment with vancomycin, linezolid, or no antibiotic. Bronchoalveolar lavage fluid levels of monocyte chemotactic protein-5 and interleukin-6 were quantified using cytometric bead array. Metalloproteinase-9 was detected by enzyme-linked immunosorbent assay and gelatin zymography. Neutrophil apoptosis in bronchoalveolar lavage was assessed by annexin V and 7-aminoactinomycin D staining. Neutrophil activity was determined by myeloperoxidase enzyme activity. Phagocytosis of apoptotic neutrophils by linezolid- vs. vancomycin treated-alveolar macrophages was examined in vitro.

MEASUREMENTS AND MAIN RESULTS

Infected mice had a significant reduction in lung bacterial titers compared with controls (p < .05) after treatment with linezolid or vancomycin. There was no difference in bronchoalveolar lavage levels of monocyte chemotactic protein-5 or interleukin-6 between vancomycin- and linezolid-treated groups. Both antimicrobials were comparable in modulating the expression of matrix metalloproteinase-9 in bronchoalveolar lavage. Neutrophil apoptosis was comparable in both vancomycin- and linezolid-treated groups at all three time points. Vancomycin showed lower myeloperoxidase activity compared with linezolid in the first 24 hrs after inoculation (p = .03), but the difference was undetectable at 48 hrs and 72 hrs. Neither compound had an impact on the process of removal of apoptotic neutrophils by alveolar macrophages.

CONCLUSIONS

Linezolid did not display an advantage over vancomycin in modulating pulmonary innate immune response in a murine model of methicillin-resistant S. aureus pneumonia.

Methylglyoxal: a stimulus to neutrophil oxygen radical production in chronic renal failure?

BACKGROUND

Chronic renal failure is characterized by oxidant stress, resulting in part from increased reactive oxygen species production by neutrophils. Plasma concentrations of methylglyoxal are increased in uraemia. Methylglyoxal activates p38 mitogen-activated protein kinase (MAPK) in endothelial cells. Activation of p38 MAPK in neutrophils enhances reactive oxygen species production through exocytosis of intracellular storage granules. We tested the hypothesis that methylglyoxal enhances reactive oxygen species production by activating p38 MAPK in neutrophils.

METHODS

Neutrophils were exposed to methylglyoxal in vitro. Activation of p38 MAPK was determined by immunoblot analysis. Exocytosis was determined by measuring plasma membrane expression of CD35 and CD66b, specific markers of secretory vesicles and specific granules, respectively. Reactive oxygen species production was determined by measuring H(2)O(2) and O(-)(2) production.

RESULTS

Methylglyoxal activated p38 MAPK and caused dose-dependent increases in CD35 and CD66b expression, which were blocked by the methylglyoxal scavenger, aminoguanidine, or the p38 MAPK inhibitor, SB203580. Methylglyoxal caused dose-dependent increases in basal and Staphylococcus aureus-stimulated H(2)O(2) production and basal and formyl-methionyl-leucyl-phenylalanine-stimulated O(-)(2) production. Enhancement of reactive oxygen species production was blocked by aminoguanidine and SB203580.

CONCLUSIONS

Methylglyoxal enhances reactive oxygen species production in neutrophils through a process involving p38 MAPK-dependent exocytosis of intracellular storage granules. These findings, together with the observation that methylglyoxal concentrations are increased in renal failure, suggest a possible role for methylglyoxal as a uraemic toxin that contributes to the oxidant stress associated with renal failure.

Essential contribution of monocyte chemoattractant protein-1/C-C chemokine ligand-2 to resolution and repair processes in acute bacterial pneumonia

Neutrophil infiltration is the first step in eradication of bacterial infection, but neutrophils rapidly die after killing bacteria. Subsequent accumulation of macrophage lineage cells, such as alveolar macrophages (AMs), is essential to remove dying neutrophils, which are a source of injurious substances. Macrophage lineage cells can promote tissue repair, by producing potential growth factors including hepatocyte growth factor (HGF). However, it remains elusive which factor activates macrophage in these processes. Intratracheal instillation of Pseudomonas aeruginosa caused neutrophil infiltration in the airspace; subsequently, the numbers of total AMs and neutrophil ingested AMs were increased. Bronchoalveolar lavage (BAL) fluid levels of monocyte chemoattractant protein (MCP)-1/CC chemokine ligand-2 (CCL2), a potent macrophage-activating factor, were increased before the increases in the number of AM ingesting neutrophils and HGF levels in BAL fluid. Immunoreactive MCP-1 proteins were detected in alveolar type II epithelial cells and AMs only after P. aeruginosa infection. The administration of anti-MCP-1/CCL2 Abs reduced the increases in the number of AM-ingesting neutrophils and HGF levels in BAL fluid, and eventually aggravated lung tissue injury. In contrast, the administration of MCP-1/CCL2 enhanced the increases in the number of AM ingesting neutrophils and HGF levels in BAL fluid, and eventually attenuated lung tissue injury. Furthermore, MCP-1/CCL2 enhanced the ingestion of apoptotic neutrophils and HGF production by a mouse macrophage cell line, RAW 267.4, in a dose-dependent manner. Collectively, MCP-1/CCL2 has a crucial role in the resolution and repair processes of acute bacterial pneumonia by enhancing the removal of dying neutrophils and HGF production by AMs.

Oxidant stress in hemodialysis patients: what are the determining factors?

Oxidant stress contributes to morbidity in hemodialysis patients. Three possible causes of oxidant stress have been suggested: the uremic state, the dialyzer membrane, and bacterial contaminants from the dialysate. Oxidant stress occurs in uremia before dialysis therapy is initiated, as evidenced by increased production of reactive oxygen species, increased levels of oxidized plasma proteins and lipids, and decreased antioxidant defenses. It has been proposed that increased production of reactive oxygen species during hemodialysis is also an important contributor to oxidant stress. Hemodialysis is associated with a transient increase in production of reactive oxygen species, particularly with cellulose membranes. In addition, surveys have shown widespread contamination of dialysate by endotoxin, which may cross membranes and prime production of reactive oxygen species by phagocytic cells. Recent studies, however, show a decrease in protein oxidation from pre- to post-dialysis and a normalization of neutrophil reactive oxygen species production. Taken together, these data suggest that uremia, per se, is the most important cause of oxidant stress in hemodialysis patients. Dialysate quality may also contribute to oxidant stress, but evidence that the dialyzer membrane plays a role is weak.

Effects of high-flux hemodialysis on oxidant stress

BACKGROUND

Neutrophil oxygen radical production is increased in end-stage renal disease (ESRD) patients and it is further enhanced during dialysis with low-flux cellulosic membranes. This increased oxygen radical production may contribute to the protein and lipid oxidation observed in ESRD patients. We tested the hypothesis that high-flux hemodialysis does not increase oxygen radical production and that it is not associated with protein oxidation.

METHODS

Neutrophil oxygen radical production was measured during dialysis with high-flux dialyzers containing polysulfone and cellulose triacetate membranes. Free sulfhydryl and carbonyl groups and advanced oxidation protein products were measured to assess plasma protein oxidation.

RESULTS

Pre-dialysis, neutrophil oxygen radical production was significantly greater than normal and increased significantly as blood passed through the dialyzer in the first 30 minutes of dialysis. Post-dialysis, however, neutrophil oxygen radical production had decreased and was not different from normal. Pre-dialysis, significant plasma protein oxidation was evident from reduced free sulfhydryl groups, increased carbonyl groups, and increased advanced oxidation protein products. Post-dialysis, plasma protein free sulfhydryl groups had increased to normal levels, while plasma protein carbonyl groups increased slightly, and advanced oxidation protein products remained unchanged.

CONCLUSIONS

The results of this study show that neutrophil oxygen radical production normalizes during high-flux dialysis, despite a transient increase early in dialysis. This decrease in oxygen radical production is associated with an improvement in some, but not all, measures of protein oxidation.

Alveolar Macrophages that Phagocytose Apoptotic Neutrophils Produce Hepatocyte Growth Factor during Bacterial Pneumonia in Mice

Hepatocyte growth factor (HGF) is postulated to play an important role in the repair of pulmonary epithelium in acute lung injury. To evaluate the role of HGF in bacterial pneumonia, the kinetics of HGF production and the cellular sources of HGF have been examined in the lungs of mice that had been intratracheally challenged with Pseudomonas aeruginosa. Neutrophil accumulation in the airway occurred immediately, reached a peak at 36 h, and then progressively declined by 14 d after infection. We found a biphasic pattern of HGF messenger RNA expression and protein synthesis in the lung after bacterial infection. The first peak for HGF production was found at 6 h after infection, and the primary source of HGF was shown to be bronchial epithelial cells. Interestingly, the second peak for HGF production, which was found around 48 to 72 h after infection, was closely associated with the increase in the percentage of alveolar macrophages (AMs) that became positive for myeloperoxidase, indicating phagocytosis of apoptotic neutrophils. The cellular source of the second peak was found to be AMs. Further, murine AMs which phagocytosed apoptotic neutrophils induced higher levels of HGF production in vitro. These results strongly indicate a novel mechanism of HGF production by AMs, which are phagocytosing apoptotic neutrophils, and the pivotal role of AMs in the healing and repair of damaged pulmonary epithelium through the production of HGF.

Phagocytosis and killing of Staphylococcus aureus by bovine neutrophils after priming by tumor necrosis factor-alpha and the des-arginine derivative of C5a

OBJECTIVES

To evaluate effects of proinflammatory mediators on phagocytosis and killing of Staphylococcus aureus, the oxidative burst (OB), and expression of receptors for opsonins by bovine neutrophils.

SAMPLE POPULATION

Neutrophils from 10 cattle.

PROCEDURE

Neutrophils were primed with recombinant bovine tumor necrosis factor-alpha (TNF-alpha) or the des-arginine derivative of bovine C5a (C5a(desArg)) and mixed with S aureus. Phagocytosis and OB were measured by use of flow cytometry. Rate of phagocytosis and intracellular killing were evaluated. Expression of receptors for immunoglobulins and the C3bi fragment of complement were estimated by use of flow cytometry.

RESULTS

Priming of neutrophils by TNF-alpha improved phagocytosis of S aureus with a concentration-dependent effect. Phagocytosis of preopsonized washed bacteria was increased by activation of neutrophils with C5a(desArg). Phagocytosis was optimal when neutrophils primed with TNF-alpha were activated with C5a(desArg). The OB of phagocytizing neutrophils was highest when TNF-alpha and C5a(desArg) were used in combination. Bactericidal activity of neutrophils was stimulated by priming with TNF-alpha or C5a(desArg). Binding of bovine IgM or IgG2 to bovine neutrophils was not stimulated byTNF-alpha, C5a(desArg), or both, and aggregated IgG1 did not bind to neutrophils regardless of their activation state. Both TNF-alpha and C5a(desArg) increased expression of beta2 integrins (CD18), with the highest expression when they were used in combination.

CONCLUSIONS AND CLINICAL RELEVANCE

The mediators TNF-alpha and C5a(desArg) stimulated phagocytic killing by neutrophils and potentiated each other when used at suboptimal concentrations. Bovine neutrophils have enhanced bactericidal activities at inflammatory sites when TNF-alpha, C5a(desArg), or both are produced locally.

Functional states of polymorphonuclear leukocytes determined by chemiluminescent kinetic analysis

During the respiratory burst, upon stimulation with both soluble and particulate matter, polymorphonuclear leukocytes (PMN) generate reactive oxygen species (ROS) and emit chemiluminescence (CL) as a result of metabolic activation. The measurement of CL has been demonstrated to be a useful tool for in vitro assessment of the opsonophagocytic function of PMN. Using component analysis of CL kinetics, we characterized the functional state of PMN by three parameters of the respiratory burst: capacity, effectiveness and velocity (CEV space). The possibility of delimiting eight different functional states of PMN is discussed. The CL kinetics shown by blood PMN in different functional states was analysed, and revealed six out of eight functional states. We conclude that CEV-estimated functional states of PMN are relative, depending on both PMN readiness to generate ROS and conditions of the CL test.

Polymorphonuclear neutrophil chemiluminescence in whole blood from blunt trauma patients with multiple injuries

BACKGROUND

Studies using isolated polymorphonuclear neutrophils (PMNs) indicate that trauma is associated with altered function of PMNs. Because isolation of PMNs can itself alter the function of these cells, we examined the relationships among measures of injury severity and several indices of PMN function using whole blood samples from trauma patients.

METHODS

Whole blood samples were obtained from 12 blunt trauma patients with multiple injuries in the intensive care unit of a Level I trauma center within 24 hours of admission and from 11 healthy volunteers. Samples were assayed for PMN chemiluminescence (CL) in response to a complement receptor 3 (CR3)-dependent agonist and for CD11b (CR3) expression. Common clinical parameters were correlated with CL and CR3 expression.

RESULTS

The CL ratio (i.e., unprimed/primed CL) was significantly correlated with initial base deficit (BD), Injury Severity Score (ISS), CR3 expression, units of packed red blood cells transfused during the interval before blood sampling, and length of intensive care unit stay (survivors only). In contrast, BD did not correlate with units of red blood cells transfused or length of stay. Similarly, ISS did not correlate with length of stay.

CONCLUSION

Significant correlations were observed between CL ratios and CR3 expression, ISS, initial BD, length of stay, and units of blood given. These data suggest that measuring CL produced by PMNs in whole blood is a potentially useful way to assess injury severity. Whereas the initial BD and ISS are indicators of how badly injured a patient is at the time of entry into a trauma center, the CL ratio may be a more useful indicator of both injury severity and prognosis.

Studies of skin-window exudate human neutrophils: increased resistance to pentoxifylline of the respiratory burst in primed cells

Human neutrophils were isolated both from peripheral blood (PB) and from aseptic inflammatory exudates obtained by the Senn's skin window technique (SW). The respiratory burst (O2- production) induced by in response to n-formyl-methionyl-lencyl-phenylalanine (fMLP) and by serum-treated zymosan (STZ) was investigated using a microplate assay. SW neutrophils were primed to enhanced fMLP-dependent O2- production in response to fMLP but not to STZ. Pentoxifylline, a cAMP-elevating drug, dose-dependently inhibited the respiratory burst in any experimental condition, but the dose-effect curves were markedly different according the stimulant used and the source of the cells. With fMLP as stimulant, a significant inhibition of the O2- production by PB neutrophils was obtained using doses of 10 micrograms/ml, while SW neutrophils were inhibited only by doses equal or higher than 100 micrograms/ml. With STZ as stimulant, the inhibition of the respiratory burst of PB neutrophils and of SW neutrophils was obtained only with doses higher than 400 micrograms/ml and 1 mg/ml respectively. Pentoxifylline dose-dependently (10 micrograms/ml to 1 mg/ml) increased the intracellular adenosine 3'-5'-cyclic monophosphate (cAMP) to the same extent in SW and in PB neutrophils. These data indicate that the priming of neutrophil oxidative metabolism by in vivo inflammation is associated with an increase in the resistance to the regulating effect of cAMP on the fMLP-dependent activation pathway of NADPH oxidase. The fact that therapeutic doses of pentoxifylline do not inhibit the respiratory burst of primed neutrophils may have relevance in the interpretation of the clinical effects of this drug.

Role of reactive oxygen species in male infertility

Human spermatozoa exhibit a capacity to generate ROS and initiate peroxidation of the unsaturated fatty acids in the sperm plasma membrane, which plays a key role in the etiology of male infertility. The short half-life and limited diffusion of these molecules is consistent with their physiologic role in key biological events such as acrosome reaction and hyperactivation. The intrinsic reactivity of these metabolites in peroxidative damage induced by ROS, particularly H2O2 and the superoxide anion, has been proposed as a major cause of defective sperm function in cases of male infertility. The number of antioxidants known to attack different stages of peroxidative damage is growing, and it will be of interest to compare alpha-tocopherol and ascorbic acid with these for their therapeutic potential in vitro and in vivo. Both spermatozoa and leukocytes generate ROS, although leukocytes produce much higher levels. The clinical significance of leukocyte presence in semen is controversial. Seminal plasma confers some protection against ROS damage because it contains enzymes that scavenge ROS, such as catalase and superoxide dismutase. A variety of defense mechanisms comprising a number of anti-oxidants can be employed to reduce or overcome oxidative stress caused by excessive ROS. Determination of male infertility etiology is important, as it will help us develop effective therapies to overcome excessive ROS generation. ROS can have both beneficial and detrimental effects on the spermatozoa and the balancing between the amounts of ROS produced and the amounts scavenged at any moment will determine whether a given sperm function will be promoted or jeopardized. Accurate assessment of ROS levels and, subsequently, OS is vital, as this will help clinicians both elucidate the fertility status and identify the subgroups of patients that respond or do not respond to these therapeutic strategies. The overt commercial claims of antioxidant benefits and supplements for fertility purposes must be cautiously looked into, until proper multicentered clinical trials are studied. From the current data it appears that no single adjuvant will be able to enhance the fertilizing capacity of sperm in infertile men, and a combination of the possible strategies that are not toxic at the dosage used would be a feasible approach.

Neutrophil migration, oxidative metabolism, and adhesion in elderly and young subjects

OBJECTIVE

To evaluate neutrophil functions in the elderly.

METHODS

We investigated the PMN migration in vivo and PMN superoxide production and adhesion in response to a variety of compounds; PMN have been isolated both from blood and from a skin experimental exudate (obtained by Senn's skin window technique) of 25 normal elderly and of 25 normal young control subjects.

RESULTS

No difference was found in PMN migration in vivo (62.9 +/- 21.3 x 10(6) and 65.5 +/- 9.1 x 10(6) PMN/cm2/24 hours in elderly and young subjects respectively), neither were different the adhesion under basal condition and after some stimuli and the superoxide production in basal condition and in response to STZ and PMA in two groups. In elderly subjects superoxide production, in response to fMLP, markedly resulted lower than in young controls both by circulating PMNs (3.6 +/- 2.7 and 9.3 +/- 3.3 nMOLES O2-/10(6) PMN respectively, p < 0.0001) and by exudate PMNs (13.6 +/- 4.3 and 19.4 +/- 6 nMOLES O2-/10(6) PMNs respectively, p < 0.005).

CONCLUSION

Many PMN functions in the elderly do not differ from young people, suggesting that the overall defense function of these cells is not affected by aging. The only parameter that we have found to be different between the two groups is the poor superoxide production after fMLP stimulus of PMNs. The stimulus- and function-specificity of this defect in PMNs from elderly subjects indicates the existence of a dysregulation of the signal transduction pathway distal to fMLP receptor and proximal to NADPH oxidase activation.

Pathophysiology of the burn wound and pharmacological treatment. The Rudi Hermans Lecture, 1995

The body's reaction to thermal injury is much more than an initial, local inflammatory response. The burn wound is a continuous, severe threat against the rest of the body due to invasion of infectious agents, antigen challenge and repeated additional trauma caused by wound cleaning and excision. The inflammatory mediators which control blood supply and microvascular permeability in the wound have been extensively studied and are largely understood. Attempts to suppress the inflammatory reaction by different drugs, have, however, been less successful. Extensive thermal injury and sepsis also results in immunosuppression. The defects causing immunosuppression are still very much under consideration. An understanding of these defects is essential for the development of therapies. The increasing interest in the control of the inflammatory reactions by cytokines may, in the near future, be of great importance.

Changes of fatty acid composition and oxidative metabolism of human neutrophils migrating into an inflammatory exudate

The peripheral blood neutrophils and the neutrophils accumulated into a skin-window experimental exudate were compared for their ability to release superoxide anion (O2-) and for their fatty acid composition, determined by capillary gaschromatography. The basal O2- release and the phorbol myristate acetate (PMA)-induced O2- release were not significantly different in the two neutrophil populations, while in response to formyl-methionyl-leucyl-phenylalanine (fMLP) the exudate cells showed an activity that was two fold higher than that of blood cells. The most significant changes of fatty acid composition of exudate versus blood cells were the following: i) increase of C16:0 (palmitic acid) from 21.3 +/- 1.2% to 23.5 +/- 1.3% (+ 10.2%) of total fatty acids (p < 0.001),ii) increase of C18:2 (linoleic acid) from 9.3 +/- 1.7% to 11.0 +/- 2.1% (+ 18.3%) (p = 0.005), iii) decrease of C20:4 (arachidonic acid) from 12.8 +/- 1.6% to 10.6 +/- 1.2% (-17.3%) (p < 0.001), whereas C18:1 (oleic acid) did not change. The total content of saturated or unsaturated fatty acids did not change. In exudate cells, a strong negative correlation was found between palmitic acid content and O2- release in response to both fMLP and PMA (r = -0.52, p < 0.02 and r = -0.49, p < 0.05, respectively) whereas arachidonic acid correlated positively, but weakly, with O2- (r = 0.40, p = 0.07 and r = 0.47, p = 0.05, with fMLP and PMA as stimulants respectively). A positive correlation was also found between the arachidonic acid content of blood cells and the number of cells that migrated into the inflammatory exudate. These results indicate that the process of extravasation from blood into the exudate causes specific and consistent modifications of the fatty acid composition of neutrophils and suggest that these modifications have a role in the activation and the regulation of the O2- forming system.

Rabbit polymorphonuclear granulocyte function during ethanol administration--migration and oxidative responses in a joint with immune complex synovitis

Functional impairments of polymorphonuclear granulocytes (PMN) are believed to contribute to hampered inflammation and host defence in alcoholics. We studied effects of i.v. ethanol administration on PMN responses in rabbits during induction of a knee-joint synovitis. The synovitis conferred systemic effects, since chemiluminescent responses of peripheral blood PMN to opsonized zymosan and phorpbol myristate acetate (PMA) increased 6.4- and 17.9-fold, respectively. Chemiluminescent responses of synovial PMN were further amplified. This up-regulation was reduced to 33% in rabbits treated with ethanol when opsonized zymosan was used as the PMN stimulus; in contrast, PMA responses were unaffected. The appearance and migration of PMN to the synovitis joint were normal despite a blood ethanol concentration of 0.5%. Thus, ethanol impaired release of oxygen metabolites from PMN, but not the delivery of cells at an inflammatory site.

Hemodialysis with cellulose membranes primes the neutrophil oxidative burst

Hemodialysis with cellulose membranes causes a complement-mediated neutropenia. Changes in neutrophil function have also been reported; however, it is unclear if these changes indicate a direct effect of the membrane on neutrophils or if they are a consequence of the neutropenia. We tested the hypothesis that neutrophil oxidative burst activity is enhanced during dialysis with cellulose membranes. Resting and Staphylococcus aureus-stimulated H2O2 production were determined predialysis and in blood entering and leaving the dialyzer during the first 30 min of dialysis and in blood leaving the membrane module in a single-pass on-line model of hemodialysis. Resting H2O2 production increased slightly but significantly during the first 30 min of dialysis. Transit of neutrophils through the dialyzer caused a marked increase in stimulated H2O2 production, indicating priming of the oxidative burst. However, priming was limited to the first 5 min of dialysis before the onset of neutropenia. In contrast, stimulation and priming of H2O2 production persisted throughout 30 min of single-pass on-line perfusion. These results indicate that cellulose membranes both stimulate and prime neutrophil oxidative burst activity but that these effects are partially obscured by neutropenia.

The chemiluminescence response of neutrophils on polymer surfaces made by glow discharge plasma polymerization

Polypropylene tubes were coated with different polymers made by glow discharge plasma polymerization. Isolated human blood neutrophils were allowed to interact with the polymer surface and the chemiluminescence response of the cells was recorded as a measure of oxidative activation. The polymers represented surfaces that differed markedly with respect to charge, hardness, and wettability. We found that all polymers stimulated the chemiluminescence response in neutrophils differently; when preincubation with human serum albumin (HSA) there was a general reduction of the chemiluminescence response particularly on one of the positively charged surface 1,2-diamino-cyclohexane (DACH). Addition of a soluble stimulus, the chemoattractant formylmethionyl-leucylphenylalanine (FMLP), to the cells caused a dramatic increase in the response on one of the hydrophobic surface hexamethylene-disiloxane (HMDSO). However, there was also a pronounced reduction in the response on polymers with acrylic acid (AA). The response was normalized after addition of HSA. Taken together, the chemiluminescence response of the neutrophils interacting with the polymer surfaces differed with regard to the type of surfaces. When HSA and FMLP were added a larger difference in the response was found. Our results showed that the activation of human neutrophil granulocytes influenced by different polymer surfaces, followed unspecific different patterns which were someway related to the specific characteristics of the polymer and from this point we came to similar conclusions made by Kaplan et al. (J. Biomater. Res. 28, 377 (1994)), that it is difficult to extrapolate any activation mechanisms from one material to another.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies of skin-window exudate human neutrophils: complex patterns of adherence to serum-coated surfaces in dependence on FMLP doses

Human neutrophils were isolated both from peripheral blood (PB) and from aseptic inflammatory exudates obtained by the Senn's skin-window (SW) technique. The respiratory burst (O2- release) and the adherence to serum-coated wells of culture microplates was investigated using a simultaneous assay. Unstimulated PB resting neutrophils did not produce a significant amount of O2- and were incapable of adhering to serum-coated plastic surfaces, while unstimulated SW neutrophils showed augmented adhesion to serum-coated culture wells. SW neutrophils were primed to enhanced FMLP-dependent O2- release in response to n-formyl-methionyl-leucylphenylalanine (FMLP). Adhesion of SW neutrophils was significantly decreased by addition of low doses (10(-10)-10(-8) M) of FMLP (from 17.1% to 8.4%, P < 0.01, N = 12), while fully activating doses (> 5 x 10(-8) M) of FMLP induced a marked increase of the cell adhesion, more pronounced in SW (39.2%) than in PB cells (27.2%). Low (5 x 10(-9) M) and high (5 x 10(-7) M) FMLP doses induced morphological changes (polarization) and actin polymerization in the neutrophils from both sources. Biphasic dose-response curves of SW neutrophil adherence were observed using FMLP, but not using concanavalin A or phorbol myristate acetate as stimulatory agents. Therefore, the adherence of SW cells appears to be regulated in a complex fashion, nonlinearly dependent on the chemotactic peptide doses and specifically regulated according to the receptors involved.

Neutrophil Priming Mechanisms of Sulfolipid-I and N-Formyl-Methionyl-Leucyl-Phenylalanine

The principal sulfatide of virulent Mycobacterium tuberculosis, sulfolipid-I (SL-I), both directly stimulates neutrophil superoxide (O(-)(2)) release and, at substimulatory concentrations, primes these cells for markedly enhanced oxidative responsiveness to other stimuli. The present study was undertaken to clarify the priming mechanisms by comparing cellular events following priming doses of SL-I with those following priming with N-formyl-methionyl-leucylphenylalanine (FMLP). We compared the involvement of the calcium cation (Ca(2+)), as well as membrane protein kinase C (PKC) activity and the translocation of NADPH oxidase-cytosolic cofactor effected by priming levels of the two agonists. The investigation led to two important conclusions. First, we clearly demonstrate that priming by both SL-I and FMLP results from activation of cellular processes that are not involved in direct oxidative activation. For example, whereas direct induction of O(-)(2) generation by FMLP and SL-I required increases in intracellular Ca(2+), an increase in intracellular calcium concentration ([Ca(2+)](i)) above basal levels was not required for priming. Second, we identified key differences in the cellular responses to priming doses of SL-I and FMLP. Whereas increased membrane PKC activity caused by priming doses of FMLP was only partially blocked by chelation of intracellular Ca(2+), Ca(2+) chelation completely inhibited the increase in membrane PKC activity caused by SL-I. NADPH oxidase-cytosolic factor translocation to plasma membranes was completely blocked by pertussis toxin when priming doses of SL-I were used. This guanine-nucleotide-binding protein inhibitor had no effect on FMLP-dependent translocation of the oxidase cofactors. The comparative approach introduced in this report provides a valuable and novel method to discern the complex interactions of various cellular processes that regulate the state of activation of stimulated cells. Copyright 1994 S. Karger AG, Basel

Ex vivo studies of polymorphonuclear neutrophils from patients with early-onset-periodontitis (II). Chemiluminescence response analysis

Previous studies have indicated that oxygen-free radicals may cause damage to the periodontal tissues. This study compared the luminol-dependent chemiluminescence response (after stimulation with either opsonized zymosan or phorbol myristate acetate (PMA) of peripheral blood polymorphonuclear leukocytes (PMN) isolated from human subjects with a healthy periodontium (n = 7), gingivitis (n = 8), adult periodontitis (n = 8), or early-onset periodontitis (n = 17). These results were also compared with those obtained in a larger reference group which consists of 50 subjects without infection or inflammation, selected on the basis of laboratory investigations. An enhanced response was defined as being 2 standard deviations above the reference group mean; a reduced response was defined as being 2 standard deviations below this mean. Although PMN from patients with either gingivitis or periodontitis were often functionally activated (when compared to the PMN from the reference group), no significant differences could be found between the 4 groups, with regard to the chemiluminescence response means obtained in a basal state or after stimulation.

Dual effects of formylpeptides on the adhesion of endotoxin-primed human neutrophils

Neutrophils, treated with sequential additions of bacterial products such as endotoxin (E. Coli lipopolysaccharide, LPS) and the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP), undergo to metabolic activation and express membrane-anchoring proteins that promote adhesion to serum-coated culture wells. By investigating the dose-response relationships of these phenomena, we have found that: (a) resting neutrophils do not produce a significant amount of superoxide (O2-) and show only minimal adhesion to serum-coated plastic surfaces; (b) fully activatory doses (> 5 x 10(-8) M) of fMLP induce the release of O2- and a significant increase of the cell adhesion; (c) pretreatment of the cells for 1 h with LPS augments cell adhesion to serum-coated culture wells in the absence of further stimulation and primes the neutrophils to enhanced fMLP-dependent O2- release; (d) addition of low, substimulatory doses of fMLP (from 10(-10) M to 5 x 10(-9) M) inhibits and reverses the adhesion of LPS-treated cells, (e) high fMLP doses ( > 10(-7) M) are additive to LPS in promoting adhesion. Phorbol-myristate acetate (> 10(-9) M) increased adhesion in both normal and LPS-treated neutrophils, but low doses of this stimulant did not inhibit adhesion. Low doses (10(-9) M) of fMLP increased intracellular cyclic AMP in both normal and LPS-treated neutrophils, suggesting that stimulus-induced rises in cAMP may be the negative signal responsible for down-modulation of adhesion.(ABSTRACT TRUNCATED AT 250 WORDS)

Role for C5 and neutrophils in the pulmonary intravascular clearance of circulating Cryptococcus neoformans

Although C5a-induced intravascular pulmonary sequestration of neutrophils has been investigated with regards to lung injury, relatively few studies have addressed the possible role for this mechanism in the intravascular clearance of circulating microorganisms. A murine model was used in which the complement-fixing, encapsulated yeast Cryptococcus neoformans (Cne) was inoculated intravenously (IV), and lung clearance of the organism was measured 24 h later. In normal mice, clearance was remarkably effective, but in leukocyte-depleted or C5-deficient (C5-) animals, clearance was significantly decreased. In vitro assays indicated that C5 was necessary for neutrophils to kill encapsulated Cne and evidence was obtained that C5a was involved. In vivo studies using light and electron microscopy demonstrated that 30 min after an IV inoculation of encapsulated yeast into C5-sufficient (C5+) mice, neutrophils accumulated in pulmonary vessels and engulfed Cne. However, in C5- mice, neutrophils failed to accumulate in pulmonary vessels and there was no endocytosis of encapsulated yeasts. These studies suggested that following Cne interaction with complement in the blood, release of C5a activated circulating neutrophils to adhere to Cne, and perhaps to adjacent endothelium, which facilitated rapid phagocytosis and killing of the organism. In contrast to the IV infection model, when Cne was inoculated into the tracheas of C5+ and C5- mice, no evidence was obtained for an early PMN-C5-dependent clearance mechanism. C5a-dependent neutrophil killing in the lung vasculature may provide important host protection against Cne during vascular dissemination and perhaps against other disseminating microorganisms that activate complement.

Terbinafine induces the PMNL priming effect and enhances in vitro PMNL fungicidal activity against Candida albicans blastospores

Terbinafine, a new antifungal drug of the allylamine category, has been shown not to interfere with some polymorphonuclear leucocyte (PMNL) functions such as chemotaxis and chemiluminescence. The aim of the present study was to elucidate the effects of terbinafine on PMNL respiratory burst activation and killing of Candida albicans blastospores by PMNLs at the biochemical and ultrastructural level by means of scanning electron microscopy (SEM). Terbinafine is shown to enhance the respiratory burst and superoxide anion release in human PMNLs stimulated by phorbol esters or chemotactic peptides, and to have a priming effect on PMNL functions. Moreover, in our experiments we found that terbinafine does not interfere with PMNL killing of C. albicans blastospores but, in fact, at the concentration found in tissues after oral administration, slightly increases it. As PMNLs play a key role in the early stages of fungal infections we suggest that in vivo terbinafine induces priming of PMNLs, and that this effect is related to enhanced candidacidal activity independent of direct drug damage to fungal particles.

Homologous priming in chemotactic peptide-stimulated neutrophils

The kinetics and dose-dependence of activation of human neutrophils exposed to sequential additions of the chemotactic peptide n-formyl-methionyl-leucyl-phenylalanine (fMLP) have been investigated by multiwell microplate assays. Treatment of neutrophils with medium-high doses (from 10(-8) to 5 x 10(-7) M) of fMLP caused activation of superoxide anion (O2-) production, but prevented further activation by a subsequent addition of an optimal dose (from 10(-7) M to 5 x 10(-7) M) of fMLP. These findings represent an example of cell desensitization, or adaptation. However, neutrophils treated with low, sub-stimulatory doses (from 10(-10) to 5 x 10(-9) M) of the peptide and then treated with optimal doses of fMLP exhibited an O2- production that was two to three-fold higher than that induced by the same optimal doses on untreated cells. A similar phenomenon of homologous priming of the oxidative metabolism of neutrophil has not previously been described or characterized. Priming was maximal after about 30 min of incubation with fMLP, which differed from desensitization, which required only a few minutes. Homologous priming was not confined to O2- production, but was also observed with the release of the granule enzyme, lysozyme. Low doses of fMLP were also capable of triggering an increase of intracellular free Ca2+ and of fMLP membrane receptors, which are possible mechanisms responsible for priming.

Chemoattractant agents and nerve growth factor stimulate human spermatozoal reactive oxygen species generation

OBJECTIVE

To investigate the ability of N-formyl-methionyl-leucyl-phenylalanine (f-MLP), complement 5a (C5a), and nerve growth factor (NGF) to stimulate human spermatozoal reactive oxygen species generation in fertile and infertile patients.

DESIGN

Prospective, controlled study measuring human spermatozoal reactive oxygen species generation after addition of f-MLP, C5a, or NGF.

SETTING

A large health maintenance organization.

PATIENTS, PARTICIPANTS

The fertile group consisted of 14 men with established fertility and normal bulk semen parameters. The infertile group was comprised of 8 men who were infertile after > 18 months of unprotected sexual intercourse.

INTERVENTIONS

The sperm samples were subjected to four test conditions: f-MLP stimulation, C5a stimulation, NGF stimulation, and no stimulation (control).

MAIN OUTCOME MEASURE

Reactive oxygen generation was measured over a 15-minute period using the method of chemiluminescence.

RESULTS

In both the fertile and infertile groups, reactive oxygen species generation was significantly enhanced by f-MLP, C5a, and NGF compared with controls. No significant difference in f-MLP- and C5a-stimulated reactive oxygen production was demonstrated between the infertile and fertile groups; however, there was a significant difference in reactive oxygen generation between infertile and fertile subjects when stimulated with NGF.

CONCLUSIONS

The current study represents the first report of f-MLP-, C5a-, and NGF-stimulated reactive oxygen species generation by human spermatozoa. Nerve growth factor enhanced reactive oxygen species production to a greater extent in infertile subjects compared with fertile subjects. This points to a possible NGF-mediated biochemical defect in the sperm of infertile patients.

Factor-specific changes in oxidative burst response of human neutrophils in skin-window exudates

Human neutrophils were isolated from blood and aseptic inflammatory exudates. The respiratory burst response was measured as superoxide (O2-) production by a microplate assay system and polarographically as oxygen consumption. Exudate cells exhibited a respiratory burst in response to n-formyl-methionyl-leucyl-phenyl-alanine (FMLP) that was two- to threefold higher than the burst exhibited by peripheral blood cells. The O2- production induced by substance P was also found to be fivefold higher in exudate cells, while the metabolic response to other stimulants such as concanavalin A (con A), phorbol-myristate acetate (PMA), NaF, and immunocomplexes was not primed. Serum-treated zymosan (STZ)-stimulated activity was primed by only 11%. In contrast, superoxide production in response to tumor necrosis factor-alpha (TNF) was decreased in exudate versus blood cells by about 50%. Therefore, the skin-window cells, compared to blood cells, appear to be at the same time primed, unmodified, and desensitized, according to the different stimulants employed.

Stimulated reactive oxygen species generation in the spermatozoa of infertile men

To investigate the possible similarities between the reactive oxygen generating systems of the leukocyte and the spermatozoa, and to identify possible biochemical differences between fertile and infertile patients, the effect of various stimulants on the production of reactive oxygen in fertile, fertile with varicocele and infertile patients was examined. Generation of reactive oxygen species by human spermatozoa was examined in 2 patient groups: a fertile group (14), which included 7 patients with a palpable varicocele, and an infertile group (16) composed of 7 patients with a palpable varicocele and 9 who remained infertile 6 months to 3 years (mean 20 months) after internal spermatic vein ligation. Various known stimulants of reactive oxygen generation in leukocytes were used to assess spermatozoal reactive oxygen production. Reactive oxygen species generation was measured by the technique of chemiluminescence. In the infertile group reactive oxygen generation was markedly increased by the calcium ionophore A23187 and the chemoattractants N-formyl-methionyl-leucyl-phenylalanine and complement 5a (p < 0.05). In addition, fertile patients with varicoceles showed significantly enhanced chemoattractant stimulated reactive oxygen generation compared to fertile donors without varicoceles. This finding of a biochemical alteration in the sperm of infertile patients and patients with varicoceles may lend support to the argument for early varicocele repair.

Retention fluids of chronic sinusitis induce neutrophil adherence to microvascular endothelial cells

The adherence of circulating leukocytes to the vascular endothelium is a critical step in the emigration of leukocytes through blood vessel walls to inflammatory lesions. The influence of nasal secretions on the adherence of neutrophils to the vascular endothelium was investigated using monolayers of human mucosal microvascular endothelial cells derived from the inferior turbinate. Preincubation of vascular endothelial cells with retention fluids from the maxillary sinus of the patients with chronic sinusitis showed increased neutrophil adherence. Recombinant IL-1 beta was also tested and found to induce adherence of neutrophils to human mucosal microvascular endothelial cells. However, no adhesive effect was observed with the nasal secretions of nasal allergy. An enzyme-linked immunosorbent assay detected considerable amounts of IL-1 beta in the chronic sinusitis retention fluids, while the amounts of IL-1 alpha and TNF-alpha were very low. The increased adhesion of the neutrophils by the retention fluids of chronic sinusitis was also neutralized by the incubation with anti-IL-1 beta antibody in a dose dependent manner. These findings suggest that IL-1 beta in the paranasal secretion of chronic sinusitis induces the adherence of neutrophils to vascular endothelium and subsequent infiltration of neutrophils in the paranasal sinuses, thus contributing to the persistence of chronic sinusitis.

Low ligand binding activities of two distinct types of Fc gamma receptor on guinea-pig peripheral blood polymorphonuclear leukocytes are differentially improved by proteolysis or platelet activating factor

The expression and ligand binding activity of Fc receptors for IgG (Fc gamma R) on guinea-pig peripheral blood polymorphonuclear leukocytes (blood PMN) have been compared with those on casein-elicited peritoneal PMN (exudate PMN). Both the PMN were found to express two distinct types of Fc gamma R, one specific for IgG1 and IgG2 (Fc gamma 1/gamma 2 R) and the other for IgG2 alone (Fc gamma 2 R), when evaluated by their reactivity to monoclonal antibodies (mAb) directed against each type of Fc gamma R. The surface density of Fc gamma 1/gamma 2 R was not significantly different between the two cell types, whereas exudate PMN expressed five times as many Fc gamma 2 R as blood PMN. Moreover, IgG immune complex (IC) binding activities of both the Fc gamma R on blood PMN were markedly low as compared with those on exudate PMN. In addition, blood PMN could not significantly generate superoxide anion (O2-) when exposed to IC. However, these lower activities were improved by protease treatment of the cells or by incubation with platelet activating factor (PAF). Fc gamma 2 R on blood PMN was found to be sensitive to pronase, whereas Fc gamma 1/gamma 2 R was resistant. Pronase-treated blood PMN showed a marked IC binding activity, though they lacked Fc gamma 2 R. This activity was completely blocked by anti-Fc gamma 1/gamma 2 R mAb, indicating that the proteolysis augments the ligand binding capacity of Fc gamma 1/gamma 2 R. In contrast, PAF was found to specifically modulate Fc gamma 2 R. The Fc gamma 2 R expression was significantly increased within 5 min incubation with PAF, whereas that of Fc gamma 1/gamma 2 R was not affected. The cells also exhibited enhanced IgG2-IC binding and subsequent O2- generating activities. These results indicate that both the Fc gamma R on blood PMN are functionally immature and are converted to exhibit intrinsic activities by proteases and PAF; such changes may occur in vivo during exudation and at inflammatory sites.

Bovine neutrophils recruited by endotoxin to a teat cistern continuously produce oxygen radicals and show increased phagocytosis and extracellular chemiluminescence

Bovine neutrophils were harvested from a teat cistern following endotoxin infusion and were compared with blood neutrophils by measurements of chemiluminescent and phagocytic activity towards C3- and IgG-opsonized and unopsonized yeast particles. Both phagocytosis and luminol-dependent chemiluminescence elicited by all three particles were enhanced in the teat cells. The increase in the luminol-dependent chemiluminescence towards C3- and IgG-opsonized particles was due to an enhanced extracellular release of myeloperoxidase. The observed increase in phagocytosis of unopsonized yeast was shown to reflect the interaction between up-regulated CR3 receptors on the surface of the teat neutrophils and the yeast particles. A high chemiluminescent activity of the teat neutrophils in both the luminol- and lucigenin-dependent systems in the absence of a phagocytic prey indicated that the NADPH oxidase was permanently active and that myeloperoxidase was continuously released by the cells. Treatment of neutrophils with cytochalasin B showed that the chemiluminescence and phagocytosis of teat neutrophils were less sensitive to this drug than that of blood neutrophils. These results indicate that the teat neutrophils have up-regulated their receptors for IgG- and C3-opsonized and unopsonized yeast on the cell surface by the action of actin. The cells also have a permanently active NADPH oxidase dependent on the association with actin and show a higher tendency than blood neutrophils to secrete the content of their primary granules during phagocytosis.

Host mediators in gingival crevicular fluid: implications for the pathogenesis of periodontal disease

During the past few years, a considerable number of studies have examined different aspects of the host response in gingival crevicular fluid (GCF), including the relationship of specific markers to the active phases of periodontal disease. Various indicators of the acute inflammatory response (the lysosomal enzymes beta-glucuronidase and collagenase, the cytoplasmic enzyme aspartate aminotransferase, and the arachidonic acid metabolite PGE2) have been shown to be associated with clinical attachment loss in chronic adult periodontitis in man and experimental periodontitis in animal models. In contrast, the relationship of indicators of the humoral immune response in GCF to active periodontal disease is equivocal. Furthermore, a number of indicators of the cellular immune response have been identified recently in GCF (i.e., Interleukin-1 alpha, IL-1 beta, tumor necrosis factor-alpha), but their relationship to active phases of periodontal disease have not been studied. The polymorphonuclear leukocyte (PMN) is the cellular hallmark of acute inflammation. Evidence from the GCF studies suggests that hyperreactivity of these cells plays a critical role in the active phases of some forms of periodontal disease. Metabolic activation of PMN can be associated with a number of potentially destructive reactions. The major effector mechanism for tissue destruction that can be specifically identified with the PMN is the synergistic effect of the release of PMN proteases and the generation of reactive oxygen metabolites by these cells. Priming of the PMN, where the PMN response is enhanced by agents that do not initiate the response, may be an important mechanism for PMN activation in the crevicular environment; for example, cytokines such as IL-1 beta and TNF-alpha, and lipopolysaccharides released from subgingival Gram-negative bacteria, can serve this function. The hypothesis proposed here argues that in addition to the severe forms of periodontal disease that have been associated with qualitative or quantitative PMN defects, tissue destruction in the periodontum can be observed with hyperreactivity of these cells. These differing conclusions do not create a dilemma, but may represent opposite ends of a balance that is no longer in equilibrium.

Platelet-activating factor primes human eosinophil generation of superoxide

Platelet-activating factor (PAF) is a potent inflammatory mediator that can cause airway obstruction and hyperresponsiveness; these processes are also associated with pulmonary eosinophilia, suggesting a link between these two events. Thus, PAF's interaction with eosinophils may provide a mechanism for airway damage. However, direct in vitro activation of eosinophils by PAF requires concentrations that are likely higher than those achieved in vivo. As a result, we investigated whether lower, more physiologic concentrations of PAF could prime eosinophils for subsequent activation to another receptor-stimulated factor, in this case formylmethionylleucylphenylalanine (FMLP). To test this hypothesis, eosinophils were preincubated (1 and 15 min) with low concentrations of PAF (1 x 10(-8) and 1 x 10(-10) M); this exposure to PAF resulted in enhanced generation of superoxide anion to FMLP stimulation. Moreover, similar concentrations of PAF decreased eosinophil density and increased expression of cell surface CR3 receptors. Finally, low, nonactivating concentrations of PAF (1 x 10(-10) to 1 x 10(-8) M) caused transient increases in eosinophil cytosolic free Ca2+ concentrations. Collectively, these responses are consistent with the hypothesis that short-term exposure to low concentrations of PAF primes eosinophils to cause an enhanced inflammatory response upon subsequent activation to another receptor agonist. The consequences of this PAF-associated phenomenon can produce an enhanced inflammatory response and airway injury.

Stimulation of neutrophil functions by C5a(desArg): an in vitro model of haemodialysis

Cuprophane membranes during haemodialysis significantly increase the plasma levels of C5a(desArg) (maximal 55 mug C5a(adesArg)/1 blood after 30 min) whereas Hemophane or Polysulphonemembranes induce only low plasma levels of C5a(desArg). C5a(desArg) generated in vitro by yeast incubation of autologous plasma stimulates PMN chemotaxis and oxidative metabolism but has no effect on enzyme release. Preincubation of whole blood with C5a(desArg) causes aggregation and changed oxidative burst activity of the isolated PMN. These changes are similar to those found in cells from patients after haemodialysis with cuprophane membranes. So the elevated plasma levels of C5a(desArg) after haemodialysis explain some of the changes in PMN functions, but additional mechanisms have to be assumed.

Oxidative metabolism of circulating granulocytes in adult respiratory distress syndrome

Among the different mechanisms involved, polymorphonuclear leukocytes (PMNs) may play a central role in the pathogenesis of adult respiratory distress syndrome (ARDS). PMNs were evaluated in 15 patients with ARDS, in 21 at risk of developing ARDS (AR), and in 36 controls (C). Spontaneous and opsonized zymosan (OZ), phorbol myristate acetate (PMA), and F-Met-Leu-Phe (F-M-L-P)-stimulated oxygen radical production was measured by luminol- and lucigenin-enhanced chemiluminescence (CL). Spontaneous CL activity of PMNs from ARDS patients was significantly greater than that from the PMN control (luminol CL, 2.8 +/- 0.6 vs. 0.8 +/- 0.1 mV, p less than 0.001; lucigenin CL, 2.0 +/- 0.6 vs. 0.30 +/- 0.04 mV, p less than 0.001), and the CL value from AR patients (luminol CL, 1.3 +/- 0.2 mV, p less than 0.001 vs. C; lucigenin CL, 0.8 +/- 0.1 mV, p less than 0.001 vs. C) was found to be between the ARDS and C patients. The peak of PMA-stimulated CL occurred earlier and it was significantly higher in ARDS patients than in AR patients (p less than 0.05) and controls (p less than 0.001). When the CL response was elicited with F-M-L-P, no difference among the three groups was found. When stimulated with OZ, the peak CL generated by PMNs from ARDS patients was significantly depressed compared with controls (luminol CL, 26.7 +/- 1.8 vs. 40.9 +/- 2.3 mV, p less than 0.01; lucigenin CL, 5.0 +/- 0.4 vs. 7.4 +/- 0.5 mV, p less than 0.005) with a similar result being obtained from AR patients (luminol CL, 32.1 +/- 2.5 mV, p less than 0.01 vs. C). Plasma from ARDS and AR patients showed a defective opsonizing capacity, suggesting in vivo complement consumption in both patient groups. No correlation between the severity of hypoxemia, the cause of ARDS, the outcome, and the different PMN functions could be established. Our results are in agreement with a determinant role of PMNs in the development of ARDS. The opposite metabolic responses may explain both the pulmonary injury and the increased susceptibility to infections observed in patients at risk of or with ARDS.

In vitro incubation with influenza virus primes human polymorphonuclear leukocyte generation of superoxide

Viral respiratory illnesses exacerbate asthma, increase airway responsiveness, and enhance the frequency of late asthmatic reactions. A number of mechanisms have been identified to explain how respiratory viral illnesses provoke wheezing, including enhanced inflammatory activity of leukocytes. To further understand how respiratory virus-caused illnesses promote leukocyte-dependent airway injury, the following study evaluated the effect of an in vitro incubation of influenza A virus on human polymorphonuclear leukocyte (PMN) generation of superoxide (O2-). PMNs were isolated from anticoagulated human blood following density gradient centrifugation; purified PMNs were then incubated (37 degrees C x 30 min) with influenza virus (PMN:virus ratio of 5:1 [egg-infective dose 50%] and 10:1) in the presence of 10% autologous serum. After incubation, the viable PMNs (greater than 95% exclusion of trypan blue) were activated, by the chemotactic peptide formyl-methionine-leucine-phenylalanine (fMLP), calcium ionophore A23187, or phorbol myristate acetate (PMA), and O2- generation was then measured. Generation of O2- to fMLP and A23187 was significantly enhanced from PMNs that had been incubated with influenza virus. Although influenza virus itself did not generate O2-, it caused a transient increase in intracellular calcium ([Ca2+]i), when measured with Indo-1-loaded cells. These results suggest that influenza virus primes PMNs to generate increased amounts of O2- and that the priming effect is associated with a transient increase in [Ca2+]. Consequently, we postulate that influenza virus priming produces PMNs of enhanced inflammatory potential to cause greater airway injury, obstruction, and responsiveness during a viral respiratory infection.

Influence of 4-hydroxynonenal on chemiluminescence production by unstimulated and opsonized zymosan-stimulated human neutrophils

The lipid peroxidation product 4-hydroxy-2, 3-trans-nonenal (HNE) has a spectrum of biological effects on different cell types depending on the concentrations tested. In particular micromolar HNE concentrations stimulate neutrophil migration and polarization whereas higher doses inhibit. In our experimental conditions, fMet-Leu-Phe (fMLP) increased CL production of both unstimulated and zymosan-stimulated neutrophils, whereas cell stimulation with low HNE concentrations as well as zymosan addition to HNE incubated cells did not enhance light emission. In contrast 10(-4) M HNE reduced CL emission by unstimulated cells nearly to background values, completely depressed CL production by zymosan-stimulated cells and reduced phagocytosis. Cysteine was found to be able to counteract the HNE effect by about 70 per cent. The possibility that this aldehyde could exert its inhibitory effect through the alkylation of NADPH-oxidase SH-groups is postulated. Moreover, our present data on differences observed between fMLP and HNE indicate a different chemotactic mechanism induced by these two classes of compounds and lead to the conclusion that the local functional features of the attracted cells may be different.

Priming effect of 2,3-dibenzylbutane-1,4-diol (mammalian lignan) on superoxide production in human neutrophils

We investigated the effect of 2,3-dibenzylbutane-1,4-diol (DBB), a mammalian lignan, on superoxide production and [Ca2+]i mobilization in human neutrophils. DBB did not generate superoxide production by itself, but enhanced the FMLP or A23187-induced superoxide production in a dose dependent manner. DBB did not influence the OAG-induced superoxide production. The priming effect of DBB was inhibited by W-7 or trifluoroperazine, but not by H-7 or staurosporine. And the priming effect of DBB was observed in the presence or absence of extracellular Ca2+. DBB enhanced the low dose FMLP-induced [Ca2+]i mobilization. These results suggest that the priming effect of DBB in human neutrophils may be caused by the activation of the calcium-calmodulin pathway but not the protein kinase pathway.

Evaluation of phagocytic cell function in an ex vivo model of hemodialysis

An ex vivo model of hemodialysis was used to evaluate the effect of dialysis membranes on phagocytic cell function. Blood was withdrawn continuously from healthy, non-uremic donors, heparinized, and pumped, single pass, through membrane modules under conditions which simulated normal dialysis conditions. The membrane modules contained membranes of cellulose, DEAE-substituted cellulose, or polysulfone. Blood was obtained from the module outlets for determination of complement activation, phagocyte elastase release, zymosan-induced phagocyte chemiluminescence, and monocyte interleukin-1 production. Significantly less complement activation occurred with the polysulfone and DEAE-substituted cellulose membranes than with cellulose membranes. Normal monocyte interleukin-1 production was not stimulated by any of the membranes used. In contrast, the cellulosic, but not the polysulfone, membranes primed the oxidative burst of the phagocytes and caused them to release elastase. DEAE-substituted cellulose had a lesser effect on elastase release than did cellulose and elastase release correlated significantly with the degree of complement activation. However, the correlation between complement activation and priming of phagocyte oxidative burst was weak, suggesting that membranes affect phagocyte oxidative metabolism through more than one mechanism. We conclude that some dialysis membranes stimulate the bacteriacidal functions of normal phagocytic cells, in part through complement-dependent mechanisms.

Resistance to the Sterne strain of B. anthracis: phagocytic cell responses of resistant and susceptible mice

Inflammatory responses were compared in vivo, and host phagocytic cell functions compared in vitro, of mice resistant (CBA/J) and susceptible (A/J) to lethal infection with the Sterne strain of Bacillus anthracis. Polymorphonuclear leukocyte (PMN) and macrophage responses at the initial site of infection were slower in A/J mice than in CBA/J mice. Whereas in A/J mice, the number of PMN ultimately responding to infection was equal to, or greater than, that in CBA/J mice, fewer macrophages accumulated. A/J mice failed to clear relatively low doses of the organisms and died. In vitro, chemotactic responses to both serum- and bacteria-derived attractants were similar for macrophages from A/J and CBA/J mice but were reduced for PMN from A/J mice. PMN and macrophages from the two mouse strains phagocytosed and killed spores in vitro to a similar extent, although killing by A/J PMN could be blocked by prior uptake of large numbers of killed spores. Thus susceptibility to lethal infection with Sterne strain correlated with the delayed influx (PMN) and reduced accumulation (macrophages) of phagocytes at the initial site of infection, but not with defective in vitro uptake or killing of spores.

Macrophage-produced oxygen radical generating activities for polymorphonuclear leukocytes

Guinea pig peritoneal macrophages were stimulated in vitro by bacterial lipopolysaccharide. After incubation, the supernatants of macrophage cultures were collected and tested for O2- production on guinea pig peritoneal polymorphonuclear leukocytes. The supernatants of macrophage cultures stimulated by lipopolysaccharide had significantly higher levels of O2- -generating activities in polymorphonuclear leukocytes, and these activities appeared in the macrophage cultures within 2 h after stimulation by lipopolysaccharide. However, the supernatants obtained from the nonstimulated cultures could not produce these activities. These activities disappeared with heating or trypsin and were not produced in macrophage cultures by incubation with cycloheximide.

Stimulation of protein synthesis in human neutrophils by gamma-interferon

Treatment of human, peripheral blood neutrophils with gamma-interferon both "primed" their ability to generate reactive oxidants and increased their rate of protein synthesis. This increased rate of protein synthesis was greatest 60 min after the addition of 100 U/ml gamma-interferon and was not due to an increased intracellular pool of radiolabelled amino acid. Analysis of the newly-synthesized polypeptides by two-dimensional polyacrylamide gel electrophoresis (PAGE) revealed two classes of proteins which were regulated by this agent. The first of these represented proteins whose rate of labelling increased very little (1-2-fold) whereas the rate of biosynthesis of a second group of proteins increased more markedly (10-20-fold). We propose that these newly-synthesized, gamma-interferon regulated proteins play an important role in the function of these cells during an acute inflammatory response.

Complement levels in septic primates treated with anti-C5a antibodies

During gram-negative sepsis it is known that endotoxin activates complement by the alternate pathway. The complement anaphylatoxin C5a, a result of this activation, is thought to play a key role in attracting and activating neutrophils in the lungs, leading to the adult respiratory distress syndrome. Complement levels were measured in primates made septic by Escherichia coli infusions. Anti-human C5a antibodies were administered to study their effect on neutrophil-mediated lung injury. Control (I), septic (II) and septic + anti-C5a antibody (III) groups (n = 4) were studied. The antibody-treated group (III) demonstrated a significant attenuation of septic shock and pulmonary edema as has been previously reported. All complement profiles were corrected for varying hemoglobin concentrations. C3, C4, and C5 levels were measured by radial immunodiffusion and were depleted in both septic groups. Once the levels were depleted from the plasma, they did not recover. The depletion of C4 indicates that classical pathway activation also occurred. C3a, C4a, and C5a levels were measured by radioimmunoassay. Significantly increased peak levels were reached in the septic groups 15 min after initiation of the E. coli infusion. There were no significant differences in early peak C3a and C4a levels between groups II and III. However, the mean peak C5a level in group III (anti-C5a antibodies) was 42% lower than that in group II, and after this early peak, C5a levels were not elevated above control levels in group III. The antibody to human C5a was thus shown to be cross-reactive with primate C5a and was specific since C3a and C4a levels were not decreased in group III.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular influx and activation increase macrophage cytotoxicity and interleukin-1 elaboration during pulmonary inflammation in rats

This study was undertaken to investigate the effects of pulmonary inflammation induced by bacillus Calmette-Guérin (BCG) on the density distribution of lavaged alveolar macrophages. We sought to determine macrophage cytotoxicity and interleukin-1 elaboration in density-defined subpopulations of macrophages during tissue inflammation. At all time points after intravenously administered BCG, lavaged alveolar macrophages contained increased percentages of higher density cells. Alveolar macrophage cytotoxicity against the rat sarcoma cell line XC increased maximally 2 to 6 days after intravenous administration of BCG before declining on Day 13. Macrophage interleukin-1 elaboration increased maximally 14 days after administration of BCG before declining on Day 23. Additionally, macrophage cytotoxicity and interleukin-1 elaboration were increased above normal in cells from each of five density fractions. We conclude that a subpopulation of higher density macrophages, probably recently derived from blood monocytes, accumulates in inflammatory sites. Cellular activation increases the cytotoxicity and interleukin-1 elaboration by macrophages in all density-defined subpopulations and obscures the relationship between cellular density and function that is present in normal animals.

Opsonin-dependent and independent surface phagocytosis of S. aureus proceeds independently of complement and complement receptors

We examined the mechanism of surface phagocytosis of Staphylococcus aureus by human polymorphonuclear leucocytes (PMN). Surface phagocytosis of unopsonized bacteria occurred, but was significantly enhanced by the presence of serum. The serum requirement was low, and a maximal effect occurred with serum concentrations of 0.25-0.5%. The opsonic effect of serum was not removed by heat inactivation of complement but was adsorbed, at low serum concentrations, by protein A, indicating that opsonin-dependent surface phagocytosis requires IgG but not C3. The requirement of opsonin-dependent surface phagocytosis for IgG was demonstrated further with purified IgG preparations as the sole opsonin. Activation of PMN by N-formyl-methionyl-leucyl-phenylalanine (FMLP) or phorbol myristate acetate (PMA) increased opsonin-independent surface phagocytosis by 47% and 66%, respectively, but had no effect on opsonin-dependent surface phagocytosis. Blockade of the PMN iC3b receptor (CR3), which has lectin-like properties, by a panel of monoclonal antibodies against the alpha- and beta-chains of CR3 did not inhibit the surface phagocytosis of opsonized or unopsonized S. aureus, and one antibody (NIMP-R10) enhanced opsonin-independent surface phagocytosis. These results indicate that the mechanism of surface phagocytosis is quite different to that observed in suspension assays. Opsonin-independent surface phagocytosis occurs and is enhanced by PMN activation, opsonin-dependent surface phagocytosis is dependent on IgG and not complement, and neither opsonin-independent nor -dependent surface phagocytosis proceeds through CR3.

Phorbol myristate acetate potentiates superoxide release and membrane depolarization without affecting an increase in cytoplasmic free calcium in human granulocytes stimulated by the chemotactic peptide, lectins and the calcium ionophore

We investigated the inter-relationships of superoxide (O2-) release, membrane depolarization and an increase in cytoplasmic free Ca2+, [Ca2+]i, in human granulocytes stimulated by various agonists. When concanavalin A or the Ca2+ ionophore ionomycin was used as stimulus, an increase in [Ca2+]i clearly preceded the onset of membrane depolarization, which was followed by O2- release. On the other hand, when N-formylmethionylleucylphenylalanine or wheat-germ agglutinin was used as stimulus, no demonstrable lag was seen in any of the responses. O2- release and membrane depolarization stimulated by all these agonists were markedly potentiated in parallel by pretreatment of cells with a low concentration of phorbol myristate acetate (0.25 ng/ml), whereas an increase in [Ca2+]i was not affected or minimally potentiated. The lag time between addition of the stimulus (concanavalin A or ionomycin) and onset of membrane depolarization or O2- release was significantly reduced by pretreatment of cells with phorbol myristate acetate, whereas the lag time between addition of concanavalin A and onset of the increase in [Ca2+]i was not affected. The dose-response curves for triggering of O2- release and membrane depolarization by each of receptor-mediated agonists in phorbol myristate acetate-pretreated or control cells were identical. These findings suggest that; (a) an increase in [Ca2+]i stimulates membrane depolarization indirectly; (b) a low concentration of phorbol myristate acetate potentiates membrane depolarization and O2- release by acting primarily at the post-receptor level, in particular, at the level distal to an increase in [Ca2+]i, but not by augmenting an increase in [Ca2+]i; and (c) the system provoking membrane depolarization and the system activating NADPH oxidase share a common pathway, which may be susceptible to a low concentration of phorbol myristate acetate.

Exudate polymorphonuclear leukocytes isolated from skin chambers are primed for enhanced response to subsequent stimulation with chemoattractant f-Met-Leu-Phe and C3-opsonized yeast particles

The ability to respond metabolically to stimulation with both soluble and particulate substances was investigated in human polymorphonuclear leukocytes (PMNLs) isolated from an aseptic inflammatory reaction. Exudate PMNLs isolated from skin chambers (E-PMNLs) and blood PMNLs isolated from the peripheral blood (B-PMNLs) of the same individual were investigated in parallel. E-PMNLs were primed, resulting in an increased chemiluminescence (CL) response to subsequent stimulation with the chemotactic peptide formyl-methionyl-leucyl-phenylalanine (FMLP) (334%) and serum-opsonized yeast particles (C3 yeast) (201%), as compared to B-PMNLs. Phorbol myristate acetate (PMA) on the other hand, induced a CL response in E-PMNLs that was only 70% of the response obtained in B-PMNLs. A similar primed state resulting in enhancement of the CL response to FMLP and C3 yeast could be induced in B-PMNLs by pretreatment with a bacterial culture filtrate. Pretreatment of E-PMNLs with the bacterial culture filtrate, however, did not increase the CL response to FMLPs any further. The enhanced functional response to FMLPs in E-PMNLs was accompanied by an increased binding of the peptide, demonstrated by a doubling of the amount of bound f-Met-Leu-[3H]Phe (209%), as compared to B-PMNLs. The increased C3-yeast-induced CL generation in E-PMNLs was accompanied by an increased ingestion and attachment of C3-opsonized yeast particles. The enhancement of phagocytosis in E-PMNLs was, however, dependent upon the opsonin used, since IgG-opsonized yeast particles were phagocytosed to the same extent by E-PMNLs and B-PMNLs, thereby indicating that selective receptor modulation is also involved in the priming of E-PMNLs for an enhanced response to C3-yeast. These results show that exudate cells isolated from skin chambers are modulated with respect to receptor-mediated functions resulting in an increased metabolic response to FMLP coupled with an increased binding of the peptide and an increased phagocytosis of C3-coated yeast particles. Receptor modulation during exudation may be an important mechanism in regulating the inflammatory response by PMNLs.

Macrophage-derived cytokines amplify immune complex-triggered O2-. responses by rat alveolar macrophages

Interleukin-1 (IL-1) and tumor necrosis factor (TNF) are monocyte macrophage-derived hormonelike regulatory proteins that participate in many physiologic and pathophysiologic processes. Several proinflammatory activities have been attributed to these cytokines, but their importance in anatomically compartmentalized inflammatory processes is unclear. The current in vitro studies have been designed to examine modulatory influences of these cytokines on O2-. responses of rat phagocytes implicated as effector cells in immune complex mediated lung injury. Purified human IL-1, recombinant human TNF (rTNF), and culture supernatant from zymosan-activated alveolar macrophages significantly amplified O2-. responses of immune complex-stimulated alveolar macrophages but did not enhance the responses of neutrophils. Equivalent concentrations of IL-1, rTNF, and alveolar macrophage culture supernatant had no direct stimulatory effect on alveolar macrophages as measured by O2-. production. Culture media from unstimulated alveolar macrophages exerted negligible effects on O2-. generation by immune complex-activated alveolar macrophages. These data indicate that O2- responses of immune complex alveolar macrophages can be enhanced by the presence of IL-1, TNF, or media from activated macrophages. It is possible that macrophage products may greatly amplify tissue injury through the enhancement of oxygen radical production.

Neutrophil function in patients on continuous ambulatory peritoneal dialysis

Frequent and recurrent episodes of peritonitis are a major cause of morbidity in patients on continuous ambulatory peritoneal dialysis (CAPD). One factor contributing to this problem may be an abnormality of neutrophil function in these patients. We have therefore quantified phagocytosis and killing by circulating and peritoneal neutrophils from patients on CAPD with and without peritonitis. Circulating neutrophils from uninfected patients showed reduced phagocytosis of both Staphylococcus epidermidis and Candida guilliermondii because of an opsonic defect in CAPD serum and because of a defect of the neutrophils themselves. In contrast, phagocytosis by circulating and peritoneal neutrophils from patients with peritonitis was normal. Intracellular killing of C. guilliermondii was normal in all groups of neutrophils but killing of S. epidermidis, the organism most commonly isolated in CAPD peritonitis, was reduced. The possible mechanisms for the enhanced neutrophil activity seen in peritonitis, and for the decreased killing of S. epidermidis in contrast to normal killing of C. guilliermondii are discussed. A defect in killing of S. epidermidis may explain why peritonitis caused by this organism can be difficult to erradicate.

A rapid technique for the isolation of highly purified, functionally intact bovine neutrophilic granulocytes

A new method for the isolation of bovine neutrophilic granulocytes from peripheral blood based on centrifugation in a discontinuous metrizamide gradient has been developed. The procedure is rapid, taking only about 2 h, and gives highly purified (greater than 90%) neutrophils in a high yield (approximately 85%). The function of the cells, as measured by chemiluminescence and migration assays, is not significantly influenced by the isolation procedure. Eosinophils can also be isolated by a slight variation of the method. Initial applications of the separation procedure indicate its usefulness in clinical studies of bovine neutrophil function. A variation between individuals in the function of the cells was thus demonstrated. Moreover, the chemiluminescence of neutrophils from infected animals was found to be greatly increased, and neutrophil migration was shown to be stimulated by in vivo ACTH treatment.