Chemiluminescent response to pathogenic organisms: normal human polymorphonuclear leukocytes

Extremely high-frequency electromagnetic radiation enhances neutrophil response to particulate agonists

The growing use of extremely high-frequency electromagnetic radiation (EHF EMR) in information and communication technology and in biomedical applications has raised concerns regarding the potential biological impact of millimeter waves (MMWs). Here, we elucidated the effects of MMW radiation on neutrophil activation induced by opsonized zymosan or E. coli in whole blood ex vivo. After agonist addition to blood, two samples were prepared. A control sample was incubated at ambient conditions without any treatment, and a test sample was exposed to EHF EMR (32.9-39.6 GHz, 100 W/m² ). We used methods that allowed us to assess the functional status of neutrophils immediately after exposure: oxidant production levels were measured by luminol-dependent chemiluminescence, and morphofunctional changes to neutrophils were observed in blood smears. Results revealed that the response of neutrophils to both agonists was intensified if blood was exposed to MMW radiation for 15 min. Neutrophils were intact in both the control and irradiated samples if no agonist was added to blood before incubation. Similarly, exposing suspensions of isolated neutrophils in plasma to MMW radiation enhanced cell response to both zymosan and E. coli. Heating blood samples was shown to be the primary mechanism underlying enhanced EHF EMR-induced oxidant production by neutrophils in response to particulate agonists. Bioelectromagnetics. 39:144-155, 2018. © 2017 Wiley Periodicals, Inc.

Influence of hormone supplementation therapy on the incidence of denture stomatitis and on chemiluminescent activity of polymorphonuclear granulocytes in blood of menopausal-aged women

Background

Menopause is a health and social problem that affects a large number of women. Inadequate quantity of steroid hormones also impacts quality of the mucous membrane of the oral cavity. During menopausal age, many women wear removable prosthetic restorations in order to replace missing teeth. Such restorations may facilitate the development of inflammations in the surface of the oral cavity, referred to as denture stomatitis.

Objective

The aim of the study was to evaluate the influence of hormone supplementation therapy on the incidence of Candida-associated denture stomatitis and on the metabolic activity of polymorphonuclear granulocytes in peripheral blood of female patients.

Materials and methods

The study was conducted on a group of women in menopausal age, users of hormone replacement therapy and of removable prosthetic restorations. Female patients were subjected to a clinical study that included interviews and physical examinations. Laboratory microbiological examinations were completed on the basis of direct swabs collected from the mucous membrane of the oral cavity and from the surface of dentures. Metabolic activity of polymorphonuclear granulocytes in peripheral blood of female patients was evaluated by means of a chemiluminescence test.

Results

Candida-associated denture stomatitis observed was characterized by a strong growth of fungi and a lower chemiluminescent activity of neutrophils in blood of female patients undergoing hormone supplementation therapy.

Conclusions

Patients using hormone supplementation therapy and removable prosthetic restorations constitute a high-risk group for Candida infections and inflammations of the mucous membrane of the oral cavity; thus they should remain under constant dental control.

Antioxidant Potential of Thymol Determined by Chemiluminescence Inhibition in Human Neutrophils and Cell-Free Systems

Thyme essential oil and thymol have antimicrobial, antifungal and antioxidant activities. Their antioxidant activity has been studied almost exclusively by means of chemical testing in order to be able to use it for food preservation purposes. The aim of this luminol amplified chemiluminescence (LACL) study was to investigate whether thymol can interfere with the production of reactive oxygen species, nitric oxide and the nitric oxide-derived peroxynitrite released by human neutrophils after activation by fMLP and PMA with and without the addition of the L-arginine (L-Arg) nitric oxide donor to the medium. The lowest thymol concentration that was still active in reducing LACL was 2.73 microg/ml, and there was a progressive linear inhibition of LACL from this concentration to 21.87 microg/ml, the highest thymol concentration investigated. This was also observed in the case of both fMLP and PMA stimulation with or without L-Arg. In cell-free systems using H(2)O(2)/HOCl(-) and SIN-1 as radical producers, a significant scavenging activity of thymol was present already at 0.08 and 0.68 microg/ml respectively, and these are very low concentrations. These findings can be related to the phenolic structure of thymol, because phenolic compounds have redox properties and play an important role in adsorbing and neutralizing free radicals and peroxynitrite, and in decomposing peroxides. Our findings in human neutrophils are pharmacologically relevant as they imply that thymol is a potential antioxidant and anti-inflammatory agent in human cells.

Budesonide reduces superoxide and peroxynitrite anion chemiluminescence during human neutrophil bursts

Many lung disorders are characterized by airway inflammation involving the recruitment of inflammatory cells, and leading to the release of oxidant and inflammatory mediators. The overproduction of superoxide anion (O(2)(*-)) and nitric oxide (NO) during the respiratory bursts of neutrophils leads to production of peroxynitrite, a highly damaging oxidant with an important role in the inflammatory loop causing airway hyper-reactivity in respiratory diseases like asthma. The aim of this study was to investigate in vitro the effects of a 1-hour incubation with budesonide at 2.5 x 10(-7), 5 x 10(-7), 1 x 10(-6), 2 x 10(-6) and 4 x 10(-6) mol/l on O(2)(*-), NO, and peroxynitrite production during the respiratory burst of human neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine (fMLP, 5 x 10(-7) mol/l) or phorbol 12-myristate 13-acetate (PMA, 2 x 10(-6) mol/l), as documented by luminol-amplified chemiluminescence (LACL). In absence of L-arginine, budesonide (5 x 10(-7) to 4 x 10(-6) mol/l) dose-dependently reduced both fMLP- and PMA-induced LACL (18.3-50.6%). In the presence of L-arginine (100 microg/ml), a NO donor increasing peroxynitrite production, LACL increased 3-5 times compared with baseline, but budesonide dose-dependently reduced LACL (25.5-59.6%). Mifepristone (4 x 10(-6) mol/l), a glucocorticoid receptor antagonist, inhibited the effect of budesonide on LACL, thus confirming that budesonide reacts with glucocorticoid receptors to exert an antioxidant activity. These results suggest that budesonide target rapidly human neutrophils leading to a fast reduction in both NO and peroxynitrite production, and are consistent with decrease in exhaled NO levels after treatment with budesonide in patients with asthma.

A combination of budesonide and the SH-metabolite I of erdosteine acts synergistically in reducing chemiluminescence during human neutrophil respiratory burst

Activated neutrophils can release superoxide anion and nitric oxide (NO), which subsequently combine with each other to yield peroxynitrite anions, powerful and harmful oxidants that preferentially mediate the oxidation of the thiol groups in proteins and non-protein molecules. These oxidants play a direct role in the inflammatory process in chronic obstructive pulmonary disease and asthma by increasing the number of neutrophils and macrophages that induce a self-sustaining phlogogenic loop. Budesonide (BUD) and erdosteine (a muco-active drug which, after metabolization, produces an active metabolite (Met I) with a sulfhydryl group) are both active in reducing the release of superoxide anion, NO and peroxynitrite, and can be administered to patients with respiratory diseases. The aim of this study was to investigate the possible synergistic in vitro effect of BUD and Met I on chemiluminescence generation during fMLP-stimulated respiratory bursts of human neutrophils with the NO donor L-arginine, added to the incubating medium. The investigated BUD concentrations ranged from 6 x 10(-8) to 1 x 10(-6) mol/l in logarithmic scale and a significant and progressive reduction in luminol-amplified chemiluminescence (LACL) was observed at concentrations ranging from 2.5 x 10(-7) to 1 x 10(-6) mol/l. The investigated concentrations of Met I varied from 0.62 to 10 microg/ml. No significant changes were observed at 0.62, 1.25, and 2.5 microg/ml, but a significant decrease in LACL was observed at 5 and 10 microg/ml. When the two drugs were combined, there was a greater significant decrease in LACL versus the single drugs with the combinations of BUD 1 x 10(-6) mol/l plus Met I 10 microg/ml, BUD 5 x 10(-7) mol/l plus Met I 5 microg/ml, BUD 2.5 x 10(-7) mol/l plus Met I 2.5 microg/ml, and BUD 1.25 x 10(-7) mol/l plus Met I 1.25 microg/ml. A further interesting finding was that the combination of BUD 2.5 x 10(-7) mol/l plus Met I 2.5 microg/ml and BUD 1.25 x 10(-7) mol/l plus Met I 1.25 microg/ml significantly decreased LACL, whereas the single concentrations had no significant effect, thus indicating the possibility of extending the duration of the effect. Our findings indicate a synergistic antioxidant effect when BUD and Met I are given together, which is of interest for counteracting the airway phlogosis involved in many respiratory diseases.

Gemifloxacin: effects of sub-inhibitory concentrations on various factors affecting bacterial virulence

This study investigated the ability of sub-MICs of gemifloxacin to interfere with the bacterial virulence parameters of adhesiveness, haemagglutination, hydrophobicity and motility, as well as their interactions with host neutrophilic defences such as phagocytosis, killing and respiratory bursts. The adhesiveness of both Escherichia coli and Staphylococcus aureus was significantly reduced to a subinhibitory concentration of 1/32 MIC. Indirect fimbriation parameters, such as hydrophobicity and haemagglutination were significantly reduced at a concentration of 1/8 MIC, as was migration (swarming). Phagocytosis and the respiratory burst measured by means of chemiluminescence were not affected, but killing was significantly increased from 1/2 to 1/8 MIC. The interpolation of these pharmacodynamic findings with pharmacokinetic curves indicates that sub-MIC concentrations of gemifloxacin can prolong antimicrobial effects on virulence determinants up to 27 h after the antimicrobial concentration has fallen below the MIC value.

Interference of sub-inhibitory concentrations of gatifloxacin on various determinants of bacterial virulence

The physico-chemical characteristics of the molecular array on the outermost surface of bacteria modulate various bacterial functions which, when expressed in the human environment, constitute important determinants of bacterial virulence. The present study investigated the ability of subinhibitory concentrations of gatifloxacin to interfere with various virulence determinants of Escherichia coli and with the adhesiveness of Staphylococcus aureus. The adhesiveness of S. aureus and E. coli to human epithelial cells was inhibited at gatifloxacin concentrations down to 1/32 and 1/64 the minimum inhibitory concentration (MIC). Sub-MICs of gatifloxacin down to 1/8-MIC significantly reduced hemagglutination and hydrophobicity, which are correlated with fimbriation and provide clues relating to the physico-chemical characteristics of the outer surface of bacteria. Swarming (motility) was reduced at concentrations down to 1/8 MIC. Phagocytosis was not affected but killing significantly increased from 1/8 to 1/2 MIC. The respiratory bursts of neutrophils investigated by a chemiluminescence procedure were not modified. The interpolation of these pharmacodynamic findings with pharmacokinetic curves indicates that the effect of sub-MIC concentrations of gatifloxacin can engender activity, prolonging antimicrobial effects on virulence determinants over 30 hours after the antimicrobial concentration has fallen below the MIC.

Effects of gatifloxacin on phagocytosis, intracellular killing and oxidant radical production by human polymorphonuclear neutrophils

The ingestion and killing of bacteria by phagocytic cells is an important step in the sequence of interactions between invading microorganisms and host defense systems and may be affected by antibiotics. We investigated the effects of gatifloxacin on the phagocytosis, killing and oxidative bursts of human polymorphonuclear neutrophils (PMNs). The percentage phagocytosis and the phagocytosis index were unaffected by exposure of Escherichia coli strains to sub-MICs of gatifloxacin to a 1/64 dilution. However a significant increase in percentage intraphagocytic killing and the killing index occurred in one E. coli strain at 1/32 MIC and in two strains at 1/16 MIC. The incubation of PMNs with sub-MICs and supra-MICs of gatifloxacin (to 32 MIC) did not affect the oxidative bursts.

Pharmacodynamic effects of subinhibitory concentrations of rufloxacin on bacterial virulence factors

It has been reported that subinhibitory concentrations (sub-MICs) of some fluoroquinolones are still capable of affecting the topological characteristics of DNA (inhibition DNA-gyrase) and that this leads to a reduction in some of the factors responsible for bacterial virulence (by means of the disruption of protein synthesis and alterations in phenotype expression), even though the microorganisms themselves are not killed. The present study investigated the ability of sub-MICs of rufloxacin, an orally absorbed monofluorinated quinolone with a long half-life (28 to 30 h), to interfere with the bacterial virulence parameters of adhesiveness, hemagglutination, hydrophobicity, motility, and filamentation, as well as their interactions with host neutrophilic defenses such as phagocytosis, killing, and oxidative bursts. It was observed that Escherichia coli adhesiveness was significantly reduced at rufloxacin concentrations of 1/32 MIC, hemagglutination and hydrophobicity were significantly reduced at concentrations of, respectively, 1/4 MIC and 1/8 MIC, and motility was significantly reduced at concentrations of 1/16 MIC; filamentation was still present at concentrations of 1/4 MIC. Phagocytosis was not affected, but killing significantly increased from 1/2 MIC to 1/8 MIC; oxidative bursts measured by means of chemiluminescence were not affected. The fact that sub-MICs are still effective in interfering with the parameters of bacterial virulence is useful information that needs to be correlated with pharmacokinetic data in order to extend our knowledge of the most effective concentrations that can be used to optimize treatment schedules, for example, single administrations, particularly in noncomplicated lower urinary tract infections.

Long-term treatment with GM-CSF in patients with chronic lymphocytic leukemia and recurrent neutropenic infections

In this prospective study we evaluated the multiple effects of long-term GM-CSF therapy on blood counts, granulocyte functions and disease progression in patients with chronic lymphocytic leukemia (CLL) with chronic neutropenia and recurrent bacterial infections. The treatment duration varied from 2 to 12 weeks. The neutrophil count was raised in all patients, by the median of 6.6-fold. The neutrophil level of 1.0 x 10(9)/l was usually reached after two weeks. The initial dose of GM-CSF was 5 microg/kg/day, and 1-7 microg/kg/day was required to maintain the neutrophil level above 1.0 x 10(9)/l. Granulocyte functions, i.e. chemiluminescence (CL), random migration, and fMLP-stimulated chemotaxis were initially depressed in all patients when compared to healthy controls. GM-CSF enhanced significantly CL even when given at small doses (less than 1 microg/kg/day), even lower than the dose required to promote granulopoiesis. We conclude that GM-CSF is effective in improving CLL associated chronic neutropenia and also enhances impaired granulocyte chemiluminescence. Thus, GM-CSF could be helpful for giving chemotherapy without neutropenic delays and for prophylaxis of infectious complications in CLL patients.

Age-associated differences in neutrophil oxidative burst (chemiluminescence)

Phagocytic defensive functions consist of a sequence of events, including migration, phagocytosis, secretion, and the release of reactive oxygen species (ROS). The last of these (also called "oxidative burst") has not received due attention in the elderly, even though it can be considered the most important event in the process of killing an invading microorganism. The aim of the present study was to investigate the oxidative burst activity of polymorphonuclear neutrophil leukocytes (PMNs) in relation to age, using a technique that specifically identifies ROS production: luminol-amplified chemiluminescence (LACL). Besides the use of LACL, a particular feature of the study was the use of five rather than just one or two different stimulants: two particulate (Candida albicans and zymosan) and three soluble ones [N-formyl-methionyl-leucyl-phenylalanine (fMLP), phorbol 12 myristate 13 acetate (PMA), and polyanetholesulfonate (liquoid)]. This approach allowed us to observe a dichotomy between the effects of Candida and zymosan (particulates), which were not significantly different in the elderly subjects compared to the young controls, and those of fMLP, PMA, and liquoid (solubles), which showed a significant reduction in LACL in the elderly group. Considering the different results obtained with the various stimulants adopted that are all believed to have NADPH oxidase as a common final target of oxidative burst, it may be postulated that aging can influence the different transductional pathways in different ways.

Penetration of brodimoprim into human neutrophils and intracellular activity

The entry of an antibiotic into phagocytes is a prerequisite for its intracellular bioactivity against susceptible facultative or obligatory intracellular microorganisms. Brodimoprim is a dimethoxybenzylpyrimidine that has recently entered into clinical use, and its uptake into and elimination from human polymorphonuclear neutrophils (PMNs), together with its effects on normal phagocytic and antimicrobial mechanisms, have been investigated. Brodimoprim uptake by PMNs was determined by a velocity-gradient centrifugation technique under various experimental conditions and was expressed as the ratio of the intracellular to the extracellular drug concentration (C/E) in comparison with the C/E of trimethoprim, which was used as a control drug. After incubation with 7.5 micrograms of brodimoprim per ml, PMNs accumulated brodimoprim (C/E, 74.43 +/- 12.35 at 30 min) more avidly than trimethoprim (C/E, 20.97 +/- 6.61 at 30 min). The cellular uptake of brodimoprim was not affected by temperature, 2,4-dinitrophenol, or potassium fluoride and was increased with an increase in the pH of the medium. It was reduced in formaldehyde-killed PMNs. The efflux of brodimoprim was very rapid (46% after 5 min). The liposolubility of brodimoprim was about three times that of trimethoprim, as was the uptake. Therefore, a possible passive transmembrane diffusion mechanism might be proposed. Brodimoprim did not decrease either phagocytosis or phagocyte-mediated bactericidal activity, nor did it affect oxidative burst activity, as investigated by luminol-amplified chemiluminescence. On the basis of the pharmacokinetic data for brodimoprim, the concentration of 7.5 micrograms/ml was chosen as the highest concentration attainable in serum by oral therapy, and at this concentration of brodimoprim, the amount of drug that penetrated into PMNs was able to maintain its antimicrobial activity without interfering with the functions of the PMNs.

Functional abnormalities in granulocytes predict susceptibility to bacterial infections in chronic lymphocytic leukaemia

Leukocyte functions were studied in 22 patients with chronic lymphocytic leukaemia (CLL) and were related to the patients' susceptibility to infections. In CLL patients with a history of infections, compared with CLL patients without infections or healthy controls, there were significant impairments of most granulocyte functions; random migration, N-formyl-methionylleucylphenylalanine (fMLP) and C5a stimulated chemotaxis and chemiluminescence response were decreased. No differences in these functions between CLL patients without infections and healthy controls were observed. Phagocytosis and intracellular killing of granulocytes were intact in all patients with CLL. By univariate analysis, neutrophil count and serum IgG level also predicted susceptibility to infections. By multivariate analyses, granulocyte chemotaxis and chemiluminescence remained as statistically significant predictors of infections. The lymphocyte functions (mitogen-induced lymphocyte proliferation and immunoglobulin production in vitro) were equally impaired in all patients with CLL and differed significantly from the respective functions in healthy control subjects. We conclude that impairments in granulocyte functions contribute to susceptibility to infections in CLL.

Differentiated U937 cells and human monocytes exhibit a differential production of extracellular oxygen species: O2.- excretion versus H2O2 diffusion

The nature and the localization of the oxidative response triggered by different stimuli in either differentiated U937 cells and peripheral blood-derived human monocytes was investigated using luminometric and cytofluorometric techniques. Differentiated U937 cells essentially produced extracellular superoxide anion (O2.-), whatever the stimulus used. Monocytes, however, responded to Salmonella typhimurium, phorbol esters, and opsonized zymosan by an intracellular, an extracellular, and both an intra- and extracellular production of oxygen species, respectively. Furthermore, H2O2 but not O2.- was detected in the extracellular oxidative response of monocytes. Using differentiated U937 cells, luminol was found to be as efficient as lucigenin in the detection of extracellular O2.-, providing sufficient concentrations of extracellular horseradish peroxidase were present. However, both azide and histidine inhibited the lucigenin-enhanced chemiluminescence, suggesting an initial and transient production of singlet oxygen by differentiated U937 cells. Taken together these results strongly suggest that, when stimulated, differentiated U937 cells directly excrete O2.- in the extracellular medium while, within monocytes, O2.- is rapidly dismutated in H2O2 which can eventually diffuse outside the cell. Such differences in the oxidative response between the two cell types could be explained by the lack of total closure of the phagosome, only observed in differentiated U937 cells.

Optimization of a phagocyte microplate chemiluminescent assay

Chemiluminescent assays have been used to quantify phagocytic activity since 1972. In recent years these assays have been adapted to the 96-well microplate format as new luminometers have been developed. In this report we describe the optimization of a lucigenin enhanced phagocyte chemiluminescent assay using a Titertek Luminoskan. Factors such as cell concentration, serum concentration in the opsonization of the zymosan used and lucigenin concentration were all optimized in our assay. In addition we have found that some of the unique features of the Luminoskan, continuous microplate agitation during the assay and microplate temperature control up to 43 degrees C, also significantly enhanced the chemiluminescent response.

Properties of Yersinia enterocolitica porins: interference with biological functions of phagocytes, nitric oxide production and selective cytokine release

We have extracted and purified Yersinia enterocolitica ATCC 9610 porins that have molecular weights of 36-38 kDa. They inhibited phagocytosis and phagosome-lysosome fusion (30%) in human monocytes and caused enhanced nitrite production. Preincubation of polymorphonuclear neutrophils with porins (1-10 micrograms/ml/10(6) cells) induced a reduction in chemotaxis, adherence to nylon wool and chemiluminescence. Human lymphomonocytes treated with Y. enterocolitica porins showed a distinctive cytokine profile. Interleukin-1 alpha, interleukin-6 and tumour necrosis factor alpha were released within 3-6 h, while interleukin-8, gamma interferon and granulocyte-macrophage colony stimulating factor were released after 18 h. Interleukin-3 and interleukin-4 were not detected at up to 48 h of incubation. In conclusion, these immunomodulating and histotropic properties may account for Y. enterocolitica infection and its sequelae.

Immunobiological activities of Helicobacter pylori porins

Studies were carried out on some biological activities of Helicobacter pylori porins in vitro. We extracted and purified a porin with an apparent molecular mass of 30 kDa. Human polymorphonuclear leukocytes preincubated with H. pylori porins showed a decrease of chemotaxis, of adherence to nylon wool, and of chemiluminescence. Used as chemotaxins in place of zymosan-activated serum or as chemotaxinogens in place of zymosan, the porins induced polymorphonuclear leukocyte migration. Human monocytes and lymphocytes cultivated in the presence of H. pylori porins released cytokines. Release of the various cytokines studied was obtained with differentiated kinetics and at various porin concentrations. Starting only 3 h after culture, tumor necrosis factor alpha is released quickly, reaching a peak at 18 h, at a porin concentration of 1 microgram/ml/10(6) cells. Interleukin-6 (IL-6) appears later, with a peak at 10 micrograms/ml/10(6) cells, while IL-8 is released after 6 h of culture, with a peak at 24 h, at a porin concentration of 10 micrograms/ml/10(6) cells, while IL-8 is released after 6 h of culture, with a peak at 24 h, at a porin concentration of 10 micrograms/ml/10(6) cells. Lymphocytes stimulated by H. pylori porins release gamma interferon after 18 h of culture at higher concentrations of porins (20 micrograms/ml/10(6) cells). Granulocyte macrophage colony-stimulating factor is released from 6 to 48 h at a concentration of 1 microgram/ml/10(6) cells, while both IL-3 and IL-4 are released after 18 h of culture at different porin concentrations (0.1 and 1 microgram/ml/10(6) cells, respectively). Our results lead us to think that during H. pylori infection, surface components, porins in particular, are able to induce a series of chain reactions ranging from the inflammatory to the immunological responses.

Polymorphonuclear leukocyte chemiluminescence induced by Actinobacillus actinomycetemcomitans and Haemophilus aphrophilus in serum and saliva

The ability of different strains of Actinobacillus actinomycetemcomitans (A.a.) and Haemophilus aphrophilus (H.a.) to trigger activation of an oxidative burst in human polymorphonuclear leukocytes (PMNL) was examined by measuring the luminol-amplified light emission--chemiluminescence (CL)--from these cells. Bacterial cells were incubated with PMNL from one healthy subject, in the presence of either active serum, heat-inactivated serum, saliva, or saliva and active serum. In the presence of active serum, all five H.a. strains and two out of five A.a. strains triggered a CL response. The CL induced in the presence of heat-inactivated serum was considerably less than that achieved with fresh serum. In the presence of only saliva, all strains induced considerably weaker CL responses than those induced in the presence of saliva with active serum. In the presence of serum, intracellular reactions appeared to be the main source of CL, while addition of saliva and active serum increased the extracellular CL. The results indicate that strain-dependent differences exist among A.a. strains in their ability to trigger the oxygen-dependent bactericidal mechanisms of human PNML. In contrast, the CL patterns of H.a. strains were equivalent. Various factors in the environment, such as activated complement and salivary compounds, affect the interaction of these species with neutrophils.

Correlation between changes in surface hydrophobicity and interaction of Streptococcus pyogenes with human polymorphonuclear leukocytes after prolonged starvation in sea water

The aim of this research was to evaluate the persistence of virulence characteristics of Streptococcus pyogenes cells after prolonged starvation in sea water. Studies were carried out on changes in viability, alterations in the chemical composition and surface hydrophobicity and the interaction of S. pyogenes with human polymorphonuclear leukocytes (PMN) after starvation. Results showed that surface hydrophobicity decreased progressively starting after three days of starvation and was correlated with the decrease in total carbohydrate, lipid and protein content. These values correlated with a better interaction of S. pyogenes cells with the PMN, as shown by a chemiluminescence increase that reached a peak after 32 days of starvation. Furthermore, bacterial cells became more easily phagocytized and killed by human PMN.

Infection of differentiated U937 cells by Salmonella typhimurium: absence of correlation between oxidative burst and antimicrobial defence

The human histiocytic lymphoma cell line U937 can be induced to differentiate along the monocyte/macrophage pathway by either phorbol myristate acetate (PMA) or by the combination of retinoic acid (RA) and 1,25-dihydroxyvitamin D3 (VD). U937 cells treated with either PMA or RA/VD were able to phagocytose Salmonella typhimurium in the presence of non-immune human serum. However, only cells differentiated by RA/VD were capable of developing an oxidative metabolic burst in response to infection. Since the oxidative burst is considered to be a potent antimicrobial mechanism, we investigated its effect on S. typhimurium. The oxidative burst failed to affect either the viability or the multiplication of S. typhimurium suggesting that it plays only a minor role in the host defence against S. typhimurium.

Effect of Haemophilus somnus on phagocytosis and hydrogen peroxide production by bovine polymorphonuclear leukocytes

The interactions between bovine polymorphonuclear leukocytes (PMNs) and the bacterium Haemophilus somnus are known to be complex. In this paper, we evaluated the effect of H. somnus on PMN function using a flow cytometric (FC) technique that simultaneously determined the extent of phagocytosis and hydrogen peroxide production by PMNs, as well as using conventional techniques, such as the nitroblue tetrazolium (NBT) and chemiluminescence assays, to analyse the PMN respiratory burst. Results from the FC and chemiluminescence assays demonstrated that in vitro exposure of PMNs to logarithmically growing H. somnus reduced the respiratory burst of PMNs obtained from healthy calves. However, this reduction was not detected by the NBT assay. A decrease in phagocytosis by PMNs could also be shown using the FC assay. In addition, PMNs from calves with acute Hemophilosis (i.e. exposed to H. somnus in vivo) showed reduced activity when compared to PMNs from healthy calves. These in vitro and in vivo observations indicate that the modulation of bovine PMN function by H. somnus may contribute significantly towards the pathogenesis of the disease.

Enhanced basal and stimulated PMN chemiluminescence activity in children with atopic dermatitis: stimulatory role of colonizing staphylococci?

In adults, intense staphylococcal skin colonization and hyperactivity of polymorphonuclear leukocyte (PMN) oxidative metabolism are characteristic features of atopic dermatitis. Precise data on childhood atopic dermatitis are lacking. In a prospective study we analysed the PMN chemiluminescence activity with special reference to staphylococcal stimuli in 19 children (mean age 6.2 years) with mild to moderate atopic dermatitis. Staphylococcus aureus was isolated from 17/19 (90%) of children with atopic dermatitis and 13/45 (29%) of healthy age-matched controls (p less than 0.001). The mean (SEM) chemiluminescence activity of unstimulated atopic dermatitis-PMN was 0.34 (0.009) (controls: 0.092 (0.003) x 10(6) cpm/10(6) PMN/min (p less than 0.02). Staphylococcal antigens (S. aureus, S. epidermidis, S. haemolyticus) induced a 1.9-3.1-fold higher peak chemiluminescence response in children with atopic dermatitis than in controls (p less than 0.05). The time interval until peak chemiluminescence activity was considerably shorter for all stimuli in atopic dermatitis. We conclude that PMN of children with atopic dermatitis are "primed", showing enhanced release of reactive oxygen metabolites even in the "resting" state, and are easily stimulated by staphylococcal antigens present on the skin of patients with atopic dermatitis from early childhood on. We speculate that PMN hyperreactivity may contribute to chronic skin damage in atopic dermatitis.

Chemiluminescence of polymorphonuclear granulocytes in the presence of selected Candida species

We monitored the respiratory burst of polymorphonuclear granulocytes (PMN) during infection in vitro with 25 strains of six Candida species with different extracellular proteolytic activity by chemiluminescence (CL). The CL-response of PMNs to viable Candida blastoconidia was compared to the response to ethanol-fixed cells of the same strain. Ethanol-fixed blastoconidia of all tested fungal strains uniformly increased the CL-response on contact. Viable fungal blastoconidia induced different CL-responses: (1) virulent C. albicans and C. tropicalis induced a low CL-response, (2) less virulent C. glabrata, C. parapsilosis and C. krusei induced CL-responses which reflected strain-specific differences, and (3) viable blastoconidia of attenuated C. guilliermondii uniformly caused a high PMN CL-response. After the CL-measurement, the killing of Candida by PMNs was assayed. High CL-response could be correlated to an augmented killing of the yeasts. These results were discussed with respect to a factor of fungal virulence, the secretion of acid proteinase.

L-arginine-dependent production of nitrogen oxides by rat pulmonary macrophages

Rat alveolar and pleural macrophages incubated with lipopolysaccharide, opsonized zymosan or recombinant interferon-gamma, but not with recombinant tumor necrosis factor-alpha, produced nitrite dose and time dependently. This production depends on the presence and amount of L-arginine in the culture medium. The precursor of the nitrite was demonstrated as being nitric oxide, by bleaching of ferredoxin at 410 nm when added to the culture medium. Addition of NG-monomethyl-L-arginine, an inhibitor of nitric oxide synthesis, and cycloheximide, a protein synthesis inhibitor, to the medium resulted in a decrease of nitrite production. Glucocorticoids were able to block the induction of nitrite production in alveolar macrophages. These data indicate that pulmonary macrophages are capable of secreting L-arginine-derived nitrogen oxides.

Correlation between modification of membrane phospholipids and some biological activity of lymphocytes, neutrophils and macrophages

Our study considered the possibility of modifying the functional response of human neutrophils, of mouse lymphocytes and macrophages treated with phospholipids having different polar groups, different isomerisms with saturated and unsaturated fatty acids from C12 to C20 carbon atoms. The results are as follows. a) Most of the phospholipids containing fatty acids from C12 to C20 cause inhibition of the blastogenic capacity of the polyclonal activators tested. b) The phospholipids tested cause a decrease in adherence of polymorphonuclear leukocytes with the exception of the phosphatidyl-choline containing saturated and unsaturated fatty acids. c) A decrease in polymorphonuclear leukocytes migrational capacity almost always occurs. d) The cells treated with L-phosphatidyl-ethanolamine having fatty acids from C14 to C17 show an increase in chemiluminescence; those treated with phosphatidyl-choline and L-phosphatidyl-glycerol show a decrease of the chemiluminescence; L-phosphatidic acid and L-phosphatidyl-ethanolamine having Microbial fatty acids (FAs) at C16 cause a decrease in the formation of phagolisosomes in the macrophages tested.

Phagocytic cell chemiluminescence using different zymosan preparations

This study compared the effectiveness of opsonized and unopsonized zymosan prepared in our laboratories with a commercially available opsonized preparation used for induction of luminol-dependent oxidative burst in phagocytic cells. The production of chemiluminescence (CL) by human whole blood, isolated human neutrophils, normal BALB c mouse splenocytes, and an immortal BALB c mouse macrophage cell line (J774A.1) was tested in an automated luminometer. Recombinant murine or human interferon-gamma (IFN-gamma) and lipopolysaccharide (LPS) were used as priming agents in some of the experiments. With human leukocytes and normal mouse spleen cells the laboratory-prepared zymosans (regardless of opsonization) induced equal or significantly greater CL than did the commercially prepared zymosan. In addition, greatly increased CL was evident with IFN-gamma- and LPS-primed neutrophils tested with our zymosans compared with the commercial preparation. These results suggest that effective zymosans capable of inducing strong, reproducible CL responses from several different phagocytic cell populations can be readily made in the laboratory.

Nifedipine administration impairs natural resistance of mice to Salmonella typhimurium

Administration of Ca2+ channel blockers in cardiac disorders and the central role of Ca2+ in modulating neutrophil functions, prompted us to investigate whether administration of nifedipine to mice would alter their natural resistance to infectious agents like Salmonella typhimurium. Neutrophil chemiluminescence (CL) in response to S. typhimurium was significantly (p less than 0.01) decreased in mice fed with nifedipine (0.015 mg/kg body weight) over a period of six months. Intracellular killing of S. typhimurium by isolated neutrophils also decreased significantly (p less than 0.01) and exponentially with nifedipine administration, representing a 42% fall at six months. In addition the drug administration lowered the survival rate of animals following challenge by a lethal dose of S. typhimurium (LD50 = 1 x 10(4) bacteria/animal). Our data suggest that long term administration of nifedipine lowers the natural resistance of mice to S. typhimurium owing to impaired neutrophil functions.

Chemiluminescence response of human phagocytes against IgG-opsonized staphylococci with and without protein A activities

The effects of immunological IgG binding to Staphylococcus aureus and IgG binding via protein A on the chemiluminescence (CL) response of human phagocytes were examined. The results obtained by enzyme immunoassay showed a clear correlation between the magnitude of the CL response and amount of IgG on protein A-deficient HL-87 strain. Despite no difference in protein A activity between 209P and Cowan I strains, the CL response to IgG-opsonized 209P cells was lower than that to Cowan I cells similarly opsonized. Moreover, the CL response to opsonized HL-87 cells was identical with that of opsonized Cowan I cells, which was a protein A-rich parent strain of the HL-87. The protein A activity of Cowan I cells was significantly decreased when the cells were treated with the Fc fraction of IgG before opsonization, but such a treatment did not change the phagocytic CL response. These results strongly suggest that IgG bound to protein A via its Fc portion has no effect on the phagocytic CL response and that IgG immunologically bound to S. aureus is responsible for the opsonization of the bacteria.

Effect of Salmonella typhimurium porins on biological activities of human polymorphonuclear leukocytes

The effect of Salmonella typhimurium porins on human polymorphonuclear leukocytes (PMNs) was studied. Labeled porins were shown to bind to the PMNs, and could be completely displaced by unlabeled porins. The binding caused modifications of membrane integrity and of the physico-chemical characteristics of the PMN surface, e.g. decreased oxidative burst, decreased hydrophobicity and altered cell morphology. The porins acted as both chemotaxins and chemotaxinogens. When PMNs were preincubated with porins their migration in the presence of commonly used chemoattractants (serum activated by zymosan or N-formyl-L-methionyl-L-leucyl-L-phenylalanine) was inhibited.

Role of cloned virulence factors (mannose-resistant haemagglutination, mannose-resistant adhesions) from uropathogenic Escherichia coli strains in the release of inflammatory mediators from neutrophils and mast cells

Genetically cloned E. coli strains expressing cloned virulence factors were studied with regard to their capability to induce inflammatory mediator release from various target cells. Among the strains were E. coli strains with mannose-resistant haemagglutination (MRH+) and mannose-resistant adhesins, e.g. E. coli 536/21 pANN 801/4, E. coli 536/21 pANN 921 and E. coli 536/21 pANN 801-1. In comparison, E. coli 536/21, E. coli 536/21 pGB 30 int and E. coli K12, without and with mannose-sensitive haemagglutination (MSH +/-), and adhesins were studied. The properties of the various strains for human PMN with regard to adherence and phagocytosis, chemiluminescence, 5-lipoxygenase activation of arachidonic acid, leukotriene formation, granular enzyme release and release of histamine from rat mast cells were analysed. It is evident that the various biochemical processes of cell activation are dissociated events. The highest chemiluminescence response is obtained with strains expressing MSH+, P-MRH+ or S-MRH+; the presence of S-adhesins suppressed the response. Highest leukotriene formation is obtained with E. coli 536/21 pANN 801-4, while E. coli with MSH was inactive. The concomitant presence of haemolysin secretion enhanced mediator release significantly. Our data suggest a potent role for mannose-resistant haemagglutination (MRH), adhesins and haemolysin as virulence factors in inducing the release of inflammatory mediators.

Heterogeneity in opsonic requirements of Staphylococcus epidermidis: relative importance of surface hydrophobicity, capsules and slime

The opsonic requirements of 65 strains of Staphylococcus epidermidis were compared in fresh and in heated normal human serum. The strains were isolated from patients with CAPD peritonitis (n = 26), neonatal septicaemia (n = 24) and nasal cultures (n = 15). A wide variation was observed in opsonic requirements between the different strains, both with fresh and with heated serum. Opsonization in heated serum proceeded less efficiently and higher concentrations (mean three-fold compared to fresh serum) were needed for adequate phagocytosis. However, a highly significant correlation was found between the minimal opsonic concentrations of fresh and of heated serum (r = 0.84, P less than 0.0005). In addition, S. epidermidis can become opsonized in agammaglobulinaemic serum. Thus, opsonization of S. epidermidis can be mediated by antibodies alone and by complement alone. Slime-producing strains and encapsulated strains did not require higher concentrations of serum to become opsonized. Opsonic requirements were highly significantly correlated with surface hydrophobicity. Enzymatic treatment rendered the strains more hydrophilic and decreased their opsonic requirements. Isolates from nasal cultures required significantly higher concentrations of both fresh and heated serum to become adequately phagocytozed, whereas isolates from CAPD peritonitis required higher concentrations of heated serum only compared to blood isolates. The uptake of S. epidermidis preopsonized in heated serum as determined in our direct phagocytosis assay did not result in a comparable chemiluminescence response.

Chemiluminescence of peripheral polymorphonuclear leukocytes from adult periodontitis patients

Polymorphonuclear leukocytes (PMN's) constitute a primary host resistance factor against infection. This study investigated the chemiluminescent (CL) response of peripheral blood PMN's isolated from human subjects with adult periodontitis. 32 subjects were categorized on the basis of age and periodontal disease status into 4 equal groups--young healthy, young diseased, old healthy and old diseased. PMN CL was stimulated using heat-killed, serum-opsonized Fusobacterium nucleatum--a specific periodontopathic gram-negative anaerobe, and Escherichia coli as a gram-negative control organism. The results showed a statistically significant enhancement (p less than 0.05) in the CL response, which was cell associated, in the young diseased subjects. This was not seen in the old subjects (p greater than 0.05), suggesting that in periodontal disease in young subjects the peripheral blood PMNs may be in a metabolically activated state. There was nevertheless a degree of variability between individual subjects within each of the 4 clinical groups.

A reference procedure to study chemiluminescence induced in polymorphonuclear leukocytes by Neisseria meningitidis

Luminol-enhanced chemiluminescence (CL) was used to study the ability of various strains of Neisseria meningitidis (MC) to induce oxidative metabolism of polymorphonuclear leukocytes (PMNL); an indirect measure of phagocytic activity. To circumvent variations related to different PMNL donors, a MC serogroup X strain was used as a control for indexing the CL responses induced by other MC strains. This procedure, with pooled serum from healthy blood donors to standardize opsonising conditions, gave reproducible and comparable results, irrespective of PMNL donors. Under these conditions, there was a highly significant difference between pathogenic and non-pathogenic MC strains as regards their ability to induce CL responses (p less than 0.001). The results indicated that the differences were due partly to opsonizing antibodies, partly to other differences related to pathogenicity of tested MC strains. These differences in leukocyte/MC interaction were also confirmed by phagocytic-killing experiments. The index procedure of CL measurements may be a suitable method to study the appearance of natural immunity to MC disease, as well as the pathogenicity of particular MC strains.

Measurement of phagocyte chemiluminescence in a microtitre plate format

Previously described assays of phagocyte chemiluminescence have required large numbers of cells and have not been able to follow responses from a large number of samples in single experiments. Recently, sensitive luminometers which employ a 96 well microtitre plate format have become available. We describe the application of this equipment to the measurement of phagocyte chemiluminescence using lucigenin to enhance the response and the estimation of the opsonic activity of serum. It was found that as few as 5 X 10(4) cells (polymorphonuclear leukocytes or monocytes) per well and a ratio of 10:1 zymosan particles to cells gave good results when opsonised with 10% whole serum. This method allows assays of opsonic activity to be performed in triplicate on large numbers of sera with a relatively small number of phagocytes and should aid the investigation of the role of opsonisation in infectious disease.

Mast cell subtypes from human lung tissue: their identification, separation, and functional characteristics

The contribution of mast cell subtypes and their different mediators to the pathogenesis of chronic obstructive lung diseases (COLD) has not yet been established. In the present study, enzymatic digestion, centrifugal elutriation and Percoll gradient centrifugation were used to obtain two populations of mast cell subtypes from human lung tissue. Mast cell subtypes were challenged with anti-human IgE, propranolol, compound 48/80, or opsonized zymosan. Both subtypes were able to release histamine, but differed in the amount of the amine release. Only the formalin-sensitive and alcian blue-positive type (FS-AB) released histamine on challenge with opsonized zymosan. The same subtype was able to release leukotriene C4 (LTC4) after challenge with anti-human IgE. The other subtype, the formalin-insensitive and alcian blue-positive type (FI-AB), did not respond to opsonized zymosan and did not release LTC4 after challenge with anti-human IgE. Stimulation with propranolol or compound 48/80 did not release histamine from the FS-AB mast cells while the FI-AB mast cells released only about 10% of their histamine content upon challenge with these secretagogues.

[Measuring chemiluminescence in phagocytic granulocytes--simultaneously a parameter of their killing function?]

The results of the chemiluminescence activity determined in whole blood samples very often were used to compare the unspecific defense mechanism of polymorphonuclear granulocytes (PMN) against causative organisms to preoperative capable risk parameters in surgery. Our investigations try to compare the results of a bacteria-induced chemiluminescence with those we received from a standardized agar killing plate-test. It could be shown that there is no correlation between the used two test systems. Therefore it is not possible to conclude from the chemiluminescence results especially made out of whole blood samples to the potency of the defense mechanism of PMN granulocytes.

Luminol dependent chemiluminescence and thiol group oxidation provoked by neutrophils is attributable to different oxidizing species

Luminol-dependent chemiluminescence and thiol group oxidation of glutathione and human serum albumin were measured in order to demonstrate whether the inhibition of polymorphonuclear leukocyte chemiluminescence by albumin was attributable to thiol group oxidation. We have shown that: 1. thiol groups on glutathione and albumin are oxidized by PMNL stimulated by soluble and phagocytic stimuli; 2. thiol group oxidation in albumin and glutathione did not correlate with the inhibitory effects of these substances on luminol-dependent chemiluminescence with respect to time course, magnitude, effects of known scavengers or extracellular activity. It was therefore concluded that thiol group oxidation was not the cause of albumin inhibition of luminol-dependent chemiluminescence; 3. a metastable oxidant was identified after PMNL activation which was capable of oxidizing thiol groups but unable to elicit chemiluminescence from luminol.

Neutrophil phagocytic and serum opsonic response of the foal to Corynebacterium equi

This study was undertaken to examine the neutrophil response to Corynebacterium (Rhodococcus) equi, and to assess the possibility of neutrophil immaturity or malfunction in predisposition to C. equi pneumonia in foals. Neutrophil phagocytosis of Corynebacterium (Rhodococcus) equi was studied in foals from birth to 6 months of age. Chemiluminescence (CL) and bactericidal assays were used to assay the phagocytic response of peripheral blood neutrophils to C. equi in vitro. Results of in vitro bactericidal and CL assays indicate that foal neutrophils are able to ingest and kill C. equi, however are significantly more efficient in the presence of opsonization with specific antibody, and less importantly complement. Neutrophil CL was significantly decreased (p greater than .05) or eliminated by antibody adsorption, heat-inactivation, or removal of serum from the assay. The ability of the neutrophil to kill C. equi, as measured by in vitro bactericidal assay, was greater than 90% killing by 6 hours, in the presence of C. equi antiserum. Bactericidal activity was reduced to less than 40% killing when C. equi adsorbed serum was used as the opsonin source. As CL results indicated complement involvement in the opsonization of C. equi, the temporal development of hemolytic and conglutinating complement was measured in normal and C. equi infected foals. Neither defects nor age-related suppression of neutrophil function or complement activity were detected in C. equi affected foals, suggesting that these are not pathogenic mechanisms involved in foal pneumonia.

Relationships of serum opsonins and complement in human experimental gingivitis

This study assessed the phagocytosis of polymorphonuclear neutrophils and the opsonic capacity of serum in experimental human gingivitis. Relationships were sought among these two measurements, clinical indices of gingivitis and complement-related opsonins. Measurements of chemiluminescence provided an index of phagocytosis and of opsonic capacity. Test group Plaque Index scores were higher than the control group on Days 7, 14, and 21, while the Gingival Index of the test group was elevated only on Day 21. Phagocytosis of test subjects' PMNs and opsonic capacity of their sera were no different from that of the controls'. Levels of C3 in both nonactivated and activated sera of the test group were significantly lower than that of the control group only on Day 14. In the test group, differences of per cent C3 conversion occurred between Days 14 and 21, and Plaque Index scores were inversely correlated with the order of per cent C3 data on these same days. Our results also indicate that complement contributes significantly to the serum opsonic capacity. The levels of developing plaque and subsequent gingival inflammation are apparently related to the degree of complement activation.

Induction of inflammatory mediators from human polymorphonuclear granulocytes and rat mast cells by haemolysin-positive and -negative E. coli strains with different adhesins

We investigated the role of various E. coli strains that expressed different adhesins and/or generated haemolysin with regard to the induction of inflammatory mediators, e.g. histamine release from rat mast cells as well as the chemiluminescence response and the release of lipoxygenase transformation products from human polymorphonuclear neutrophils. Our data show that the degree of haemagglutination did not parallel the induction of the chemiluminescence response. Haemolysin-negative bacteria with different adhesins induced more 5-hydroxyeicosatetraenoic acid as compared to haemolysin-positive bacteria, which generated more leukotriene B4 as compared to 5-hydroxyeicosatetraenoic acid. Among the leukotrienes, more leukotriene B4 as compared to leukotriene C4 was released from peripheral leucocytes. Studies with rat mast cells showed that histamine release was dependent on the haemolysin activity expressed by washed bacteria or present within the bacterial culture supernatant. Histamine release was markedly diminished when haemolysin activity decayed. Several haemolysin-negative bacteria with defined adhesins also released histamine, suggesting that, in addition to haemolysin, other factors contribute to mediator release. Thus, various properties of bacteria (e.g. adhesins, haemolysin) may participate to varying degrees in the induction of inflammatory mediators, e.g. oxygen radicals, lipoxygenase transformation products, leucotrienes and histamine.

Platelet-activating factor (PAF-acether) induced leukotriene C4 formation and luminol dependent chemiluminescence by human eosinophils

Human eosinophils are capable of synthesizing almost exclusively the strongly spasmogenic compound LTC4 when stimulated with either the calcium ionophore A 23187 or opsonized zymosan (OZ). Although PAF-acether in concentrations ranging from 10 nM to 1 microM is hardly capable of inducing significant LTC4 synthesis itself, it significantly enhances the OZ-induced LTC4 formation at a concentration of 1 microM. However, at a concentration of 10 microM, PAF-acether itself is capable of inducing LTC4 formation comparable with that induced by OZ. PAF-acether, at a concentration of 10 microM (and not at a concentration of 1 microM) is also capable of inducing a luminol dependent chemiluminescent response by eosinophils. The PAF-acether antagonist BN 52021 at a concentration of 0.1 mM not only partially inhibited the PAF-acether induced LTC4 formation but also the OZ induced LTC4 formation. Since an equal inhibition is found the inhibitory mode of action of BN 52021 is most likely directed towards a common pathway. Taken together, these results suggest that eosinophils may be triggered by high locally reached concentrations of PAF-acether to release inflammatory and bronchoconstrictive mediators. This may be of importance for the pathogenesis of the allergen induced late phase asthmatic reaction.

Albumin bound to the surface of M protein-positive streptococci increased their phagocytosis by human polymorphonuclear leukocytes in the absence of complement and bactericidal antibodies

Using a phagocytosis assay (Leijh 1980, Infect. Immun. 30, 421), determination of chemiluminescence, and transmission electron microscopy, the influence of the binding of albumin to M protein-positive group A streptococci on their phagocytosis by human polymorphonuclear leukocytes (PMNL) was investigated. Coating of streptococci with albumin in the absence of other serum components enhanced phagocytosis but not killing of the bacteria. Complement had no additional effect on engulfment. Fibrinogen reduced the enhancing effect of albumin. Albumin had no additional effect on the high phagocytosis rate of an M-protein-negative strain. It could be demonstrated that human PMNL bound human serum albumin-gold conjugate. The results are discussed with regard to the role of plasma proteins in the phagocytosis of streptococci under in vivo-conditions.