Biomedical subjects

C Babin-Chevaye

Publications and source records attributed to C Babin-Chevaye.

At least 19 recordsLinked to original sources

PubMed2005

Interaction of rifalazil with oxidant-generating systems of human polymorphonuclear neutrophils.

It is well acknowledged that ansamycins display immunosuppressive and anti-inflammatory properties in vitro and in vivo. Rifalazil, a new ansamycin derivative, has not been studied in the context of inflammation. In particular, there are no data on the possible interference of rifalazil with oxidant production by phagocytes. We have compared the antioxidant properties of rifalazil to those of rifampin, a drug well known in this context, by using cellular and acellular oxidant-generating systems. Oxidant production by polymorphonuclear neutrophils was measured in terms of cytochrome c reduction, lucigenin-amplified chemiluminescence (Lu-ACL), and the 2',7'-dichlorofluorescin diacetate H2 (DCFDA-H2) technique (intracellular oxidant production). Rifalazil impaired O2- production in a concentration-dependent manner, with 50% inhibitory concentrations (IC50) (concentrations which inhibit 50% of the response) of 5.4 (30 and 60 min of incubation) and 6.4 (30 min) mg/liter, respectively, for phorbol myristate acetate (PMA) and formyl-methionyl-leucyl-phenylalanine (fMLP) stimulation. In agreement with the published fMLP-like activity of rifampin, the inhibitory effect of rifampin was significantly greater for fMLP (IC50 of 5.6 mg/liter) than for PMA (IC50 of 58 mg/liter) stimulation. Alteration of intracellular oxidant production was also observed with IC50 values similar to those obtained by the cytochrome assay. In addition, rifalazil and rifampin (> or = 25 mg/liter) scavenged O2-, as demonstrated by the acellular (hypoxanthine-xanthine oxidase) system. Interference with light detection systems was evidenced for both drugs by Lu-ACL. The clinical relevance of the antioxidant effect of rifalazil demonstrated in vitro, in particular its potential anti-inflammatory activity, requires further investigation.

Anti-Bacterial Agents↗

PubMed2005

Accumulation of azithromycin and roxithromycin in tracheal epithelial fetal cell lines expressing wild type or mutated cystic fibrosis transmembrane conductance regulator protein (CFTR).

Macrolides are accumulated in phagocytes, partially via an active transport system; the membrane carrier is not identified but many data indicate a link with the P-glycoprotein family which includes the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. We have used two epithelial cell lines which express either wild-type (N cells) or mutated (homozygous deltaF508) (F cells) CFTR to study the cellular accumulation of two macrolides (azithromycin and roxithromycin). Adherent cells were incubated with the radiolabeled drugs before extensive washings and counting. Azithromycin was better (about 2-fold) accumulated in F cells up to 60 min but then plateaued, whereas accumulation continued without saturation over 3 hours in N cells. Roxithromycin was also better (1.5-fold) accumulated in F cells at 15 and 30 min, but there were no differences at further incubation times. Macrolide efflux from loaded N and F cells, and the susceptibilities of the carrier systems (entry and efflux) to various pharmacologic agents were similar to those previously observed with phagocytes. These data suggest that the macrolide carriers (for entry and efflux) are not strictly specific for phagocytes and that the CFTR protein plays a role in macrolide uptake.

Analysis of Variance↗

PubMed2003

Interaction of macrolides and ketolides with the phagocytic cell line PLB-985.

Interactions between antibacterial agents and polymorphonuclear neutrophils (PMNs) are a major focus of investigation. Owing to the variable drug susceptibility of PMNs from different individuals, in vitro studies require samples from large panels of healthy volunteers to reach statistical significance. Here, we used a phagocytic cell line, PLB-985, which can differentiate into mature PMNs in vitro, for the study of cellular interactions (drug uptake and antioxidant effects) of two macrolides (azithromycin and roxithromycin) and four ketolides [HMR 3004, HMR 3647 (telithromycin), HMR 3562 and HMR 3787]. The oxidative burst of differentiated (D) cells was inhibited by macrolides and ketolides. IC50% values (concentrations impairing the oxidative burst by 50%), determined after 30 min of incubation, were as follows for azithromycin, roxithromycin, HMR 3004, telithromycin, HMR 3562 and HMR 3787, respectively: 40, 39, 15, 23, 26, and 33 mg/l (fMLP stimulation) and 37, 86, 39, 43, 14, and 31 mg/l (PMA stimulation). These values were similar to those obtained with PMNs. Uptake of the two macrolides was significantly lower in non-differentiated (ND) cells than in D cells and PMNs. The cellular/extracellular (C/E) concentration ratios at 60 min for PMNs, D and ND PLB were respectively 67, 25 and 11 (roxithromycin) and 159, 137 and 48 (azithromycin). Ketolide uptake by ND-PLB was also significantly lower than that obtained with PMNs (C/E ratios at 60 min were about 75 versus 265 (HMR 3004), 36 vs 230 (telithromycin), 75 vs 235 (HMR 3562) and 20 vs 130 (HMR 3787). Although the active carrier system seemed to be present in ND cells, its activation pathway was not functional. Thus, the PLB-985 cell line is a good in vitro model for studying drug-PMN interactions. The use of ND and D cells may shed light on the nature and activation pathways of macrolide transport systems present on the PMN membrane.

Anti-Bacterial Agents↗

PubMed2002

Structure-activity relationships among 9-N-alkyl derivatives of erythromycylamine and their effect on the oxidative burst of human neutrophils in vitro.

Macrolide antibiotics have recently triggered much interest owing to the immunomodulatory potential of some derivatives, particularly in the field of inflammatory diseases. Among the possible mechanisms underlying these anti-inflammatory effects, macrolide-induced inhibition of oxidant production by phagocytes has attracted much attention. We and others have previously reported that erythromycin A-derived macrolides impair the phagocyte oxidative burst, a property linked to the presence of L-cladinose. However, we have also demonstrated that other substituents can be involved in the modulation of phagocyte function. Here we have extended the analysis of structure-activity relationships by studying the effects of five 9-N-alkyl derivatives of erythromycylamine on oxidant production by human neutrophils in vitro. LY211397 (2-methoxyethyl derivative) neither altered cell viability nor superoxide anion production. LY281389 (n-propyl derivative) did not alter cell viability and was slightly more inhibitory than erythromycylamine for the production of superoxide anion; its IC50 (concentration that inhibits 50% of the neutrophil response) was about 18 and 24 microM (versus 72 and 74 pM for erythromycylamine) after 60 min of incubation following fMLP and PMA stimulation, respectively. LY80576 (N-phenyl-3-indolylmethyl derivative), LY281981 (3-phenyl-n-propyl derivative) and LY57843 (benzyl derivative) all displayed cellular toxicity at high pharmacological concentrations after 30 to 60 min of incubation. Interestingly, these latter three drugs exhibited a rapid (5 min incubation) and strong inhibitory effect on the neutrophil oxidative burst from either stimulus, with IC50 values of 3 to 10 pM. Further in-vitro and in-vivo investigations are required to analyze the anti-inflammatory potential of these three derivatives.

Cell Survival↗

PubMed1997

Induction of interleukin-1 and subsequent tissue factor expression by anti-proteinase 3 antibodies in human umbilical vein endothelial cells.

OBJECTIVE: To assess the ability of anti-proteinase 3 (anti-PR3) classic antineutrophil cytoplasmic antibodies (cANCA) to stimulate endothelial expression of tissue factor (TF), which is the main initiator of the coagulation cascade that can lead to endothelial injury and thrombosis in patients with Wegener's granulomatosis. METHODS: Human umbilical vein endothelial cells (HUVEC) were grown to confluence and stimulated with affinity-purified anti-PR3 antibodies, Igs from healthy subjects, and endotoxin (lipopolysaccharide) as positive control. RESULTS: TF activity was generated in anti-PR3-stimulated cells, as shown by a chromogenic test. This activity was inhibited by specific anti-TF antibodies. TF messenger RNA (mRNA) was found in anti-PR3-stimulated cells, as detected by reverse transcriptase-polymerase chain reaction, but not in cells stimulated with irrelevant human Igs or Igs from normal control sera. TF expression reached maximum levels 12 hours after exposure to the anti-PR3 cANCA, and did not require complement. TF mRNA expression was inhibited by cycloheximide, suggesting a requirement for protein synthesis. When added to the incubation medium, interleukin-1 (IL-1) receptor antagonist inhibited the induced TF mRNA expression, suggesting that cANCA-stimulated cells initiate IL-1 synthesis. Moreover, cANCA induced IL-1alpha mRNA before TF mRNA. CONCLUSION: This study showed that anti-PR3 treatment of HUVEC induces sequential expression of IL-1alpha mRNA and TF mRNA, as well as their corresponding proteins. Both proteins could have pathogenic roles in the vasculitic process, since TF is the main initiator of the coagulation cascade.

Antibodies, Antineutrophil Cytoplasmic↗

PubMed1996

Inhibition of human neutrophil binding to hydrogen peroxide-treated endothelial cells by cAMP and hydroxyl radical scavengers.

Hydrogen peroxide (H2O2) increases adherence of human polymorphonuclear neutrophils (PMN) to cultured human umbilical vein endothelial cells (HUVEC). Catalase and HO. scavengers did not affect the increased PMN adherence to HUVEC stimulated by other compounds such as phorbol myristate acetate (PMA) and thrombin, showing that the observed effect was H2O2- and HO.-specific. This effect was inhibited by hydroxyl radicals (HO.) scavengers and not by iron-chelators that do not penetrate the cells, suggesting the involvement of intracellular HO. in the increased adherence mechanism. An increase in cAMP inhibited H2O2-induced adherence, as observed with isoproterenol, isobutylmethylxanthine, and dibutyryl-cAMP. Similarly, pentoxifylline (Ptx), an HO. scavenger that also increases cAMP, inhibited H2O2-mediated adherence but had no effect on that induced by PMA or thrombin. PKA inhibitors cancelled the Ptx-induced inhibition of H2O2-mediated adherence. However, PKA inhibitors or atrial natriuretic peptide that decreases cAMP did not increase adherence, showing that decrease in cAMP is not responsible for increased adherence. HO. scavengers did not alter the H2O2-induced reduction in cAMP levels, but did inhibit the effect of H2O2 on adherence. We conclude that HO. mediates the H2O2-induced increased in PMN adherence to HUVEC, and that the increase in cAMP that mediates PKA activation downregulates this effect.

1-Methyl-3-isobutylxanthine↗

PubMed1995

Effects of pentoxifylline on the adherence of polymorphonuclear neutrophils to oxidant-stimulated human endothelial cells: involvement of cyclic AMP.

Cultured human umbilical vein endothelial cells (HUVECs) treated with reactive oxygen species (ROS) show increased adherence of polymorphonuclear leukocytes (PMNs). Because pentoxifylline (PTX) is known to inhibit cell interactions, we studied PMN adherence to ROS-stimulated HUVECs pretreated with PTX. ROS were generated by the oxidation of hypoxanthine by xanthine oxidase, giving rise to superoxide anion and hydrogen peroxide. Human PMNs were then added to HUVEC monolayers. After various times, the cultures were washed and the number of adherent PMNs was estimated by measuring myeloperoxidase in the total cell homogenate. PTX inhibited adherence in a concentration-dependent manner. Moreover, the increase in intracellular cAMP content varied with the PTX concentration. Isobutylmethylxanthine (IBMX) and isoproterenol (ISO) which increase intracellular cAMP content, also inhibited the adherence of PMNs to ROS-stimulated HUVECs. We conclude that cAMP is probably involved in the intracellular regulation of ROS-mediated PMN adherence to endothelial cells.

1-Methyl-3-isobutylxanthine↗

PubMed1992

K562 cells produce an anti-inflammatory factor that inhibits neutrophil functions in vivo.

We have previously reported that K562, a chronic myelogenous leukemia cell line, releases a low molecular weight factor (6 to 8 Kd) that inhibits human polymorphonuclear neutrophil (PMN) adherence and adherence-related functions tested in vitro. We now report that this factor, which we have named K562 inhibitory factor (K562-IF), has potent anti-inflammatory activity in mice, associated with an inhibition of PMN functions. Its in vitro actions were less marked with mouse PMN than with human PMN. They included (1) an inhibition of both nonstimulated locomotion and locomotion induced by FMLP or serum; (2) an inhibition of the chemiluminescence induced by opsonized zymosan, but not that induced by phorbol myristate acetate or FMLP; (3) an inhibition of the degranulation stimulated by opsonized zymosan, as reflected by lactoferrin and lysozyme release; and (4) a decrease in arachidonic acid release and leukotriene B4 production by A23187-stimulated PMN. The in vivo actions of K562-IF after intraperitoneal injection included (1) an inhibition of subcutaneous PMN accumulation at the site of injection of opsonized zymosan (PMN accumulated neither outside the vessels nor intravascularly, as shown by means of histochemistry); (2) an inhibition of neutrophil accumulation in the peritoneum of mice having received sodium caseinate or opsonized zymosan intraperitoneally; and (3) lysozyme concentration in neutrophils having reached the peritoneum after opsonized zymosan treatment equal to that in blood, suggesting diminished release. PMN influx and degranulation in the peritoneum were reduced by 50% after 3 hours of treatment with 1 microgram of K562-IF (equivalent to the effect of 120 micrograms of prednisolone). Taken together, these results show that K562-IF is a potent anti-inflammatory agent that acts by inhibiting PMN functions.

Animals↗

PubMed1991

Effect of a factor released by K562 malignant cells in culture on human neutrophil bactericidal activity.

We have previously demonstrated that k562 malignant cells in culture contain and release a low-molecular-mass (8-kDa) factor that inhibits adherence-related functions of neutrophils but does not alter fMet-Leu-Phe- or phorbol ester-induced oxidative burst (M. Amar, N. Amit, T. Pham Huu, S. Chollet-Martin, M.T. Labro, M.A. Gougerot-Pocidalo, and J. Hakim, J. Immunol. 144:4749-4756, 1990). In this study, we investigated the effects of this factor, referred to as inhibitory factor 1 (IF1), on the bactericidal activity of human polymorphonuclear cells (PMNs) on Staphylococcus aureus opsonized in various ways. S. aureus was used either nonopsonized or opsonized with heat-inactivated serum or normal serum containing complement factors. The bactericidal activity of PMNs preincubated with IF1-treated or control medium was examined by counting the surviving bacteria. The ability of IF1-treated PMNs to kill bacteria was diminished when they were opsonized with normal serum. When S. aureus was not opsonized or was opsonized with heat-inactivated serum, the bactericidal activity of IF1-treated PMNs was similar to that of controls. Likewise, the phagocytosis of IF1-treated PMNs was diminished when S. aureus was opsonized with normal serum but was not altered when S. aureus was not opsonized or was opsonized with heat-inactivated serum. These results suggest that the decrease in killing might be due to defective ingestion. The chemiluminescence response of IF1-treated PMNs was inhibited when S. aureus was not opsonized or was opsonized with normal serum. No effect on chemiluminescence was observed when S. aureus was opsonized with heat-inactivated serum. These results suggest that IF1 interferes not only with S. aureus stimulation of PMNs via complement receptors but also with oxygen-dependent bactericidal activity.

Biological Factors↗

PubMed1989

Comparison of the in-vitro effect of several macrolides on the oxidative burst of human neutrophils.

We have compared the in-vitro interaction of five macrolides (roxithromycin, erythromycin, spiramycin, oleandomycin and josamycin) with human neutrophils (PMN). Only roxithromycin strongly impaired the oxidative burst of PMN assessed by luminol amplified chemiluminescence, superoxide anion generation, and myeloperoxidase-mediated iodination of proteins. This effect was observed only for high concentrations of this drug (100 and 50 mg/l). Furthermore, the sensitivity of PMN to the depressive effect of roxithromycin permitted the definition of two kinds of PMN: in Highly Sensitive (HS)-PMN, the oxidative response was completely abolished while in Moderately Sensitive (MS)-PMN, a decreased, but yet measurable (20-50% of the control), response was obtained. The roxithromycin-induced depression of PMN was time-dependent and partly reversed by washing. Chemotaxis was also impaired by roxithromycin (100 mg/l) but phagocytosis of Klebsiella pneumoniae was unaltered even at high concentrations of the drug. Since roxithromycin displays the highest intracellular uptake, compared with the other macrolides assessed in this study, this could explain the results observed here. The relevance to the clinical situation needs further study. This effect of roxithromycin could be useful to control the inflammatory process associated in certain infectious diseases, in particular if high concentrations of the drug are obtained in tissues.

Anti-Bacterial Agents↗

PubMed1989

Synergistic interaction of josamycin with human neutrophils bactericidal function in vitro.

Josamycin, a 16-membered ring macrolide is concentrated up to 20-fold in phagocytic cells compared with serum. We have studied the in-vitro interaction of this drug with human neutrophils (PMN) bactericidal function by using two strains resistant to this antibiotic, Pseudomonas aeruginosa and Klebsiella pneumoniae, and a sensitive one, Staphylococcus aureus 209P. It was shown that josamycin-pretreated adherent PMN displayed an increased phagocytic activity (about 30 to 40%) for S. aureus or K. pneumoniae, mainly due to the recruitment of an additional phagocytizing subset of PMN. Furthermore, the bacterial killing was enhanced in josamycin-treated PMN in a dose-dependent manner for K. pneumoniae (60-130% increase in the range of concentration 0.1-25 mg/l) and independently of the dose for S. aureus (about 425-460% increase for josamycin 0.1-10 mg/l). P. aeruginosa killing by whole blood was also significantly increased in the presence of 10 and 1 mg/l of josamycin. Other PMN functions were not much altered by josamycin except an enhancement of the formyl-methionyl-leucyl-phenylalanine-induced oxidative response. Chemotaxis was only increased by the presence of a high concentration (100 mg/l) of josamycin. These data suggest that the bactericidal synergy between PMN and josamycin could be related, partly at least, to a direct enhancing effect of josamycin on some PMN functions such as phagocytosis, chemotaxis and FMLP-induced chemiluminescence. On the other hand, alterations of bacteria, either inside the phagolysosome or in the extracellular medium, could lead to an enhanced susceptibility to the phagocytes' microbial mechanisms.

Chemotaxis, Leukocyte↗

PubMed1989

[Bactericidal synergy of josamycin and human polynuclear neutrophils in vitro].

Due to their high intracellular uptake, macrolides may interfere with phagocytes antibacterial system. We have studied the interaction of josamycin with bactericidal activity of human neutrophils (PMNs) or whole blood, in vitro. PMNs preincubated with josamycin (100-0.1 mg/l) display an increased phagocytic ability for K. pneumoniae, independently of the concentrations of josamycin; this effect appears to correlate with the recruitment of an additional population of phagocytizing PMNs without alteration of the mean number of PMN-associated bacteria, whatever the experimental conditions (adherent or non adherent PMNs). PMNs bactericidal function is also enhanced in the presence of josamycin in a dose-dependent manner (mean increase 60 to 370% for josamycin 0.1 to 10 mg/l). Bactericidal activity of whole human blood for P. aeruginosa (a strain resistant to the lytic effect of serum) is increased with a mean survival (CFUt min/CFU 0 min) of 24 and 71% at 60 and 120 min respectively, in the presence of josamycin 10 mg/l, and 42 and 128% in the presence of josamycin 1 mg/l, compared to the survival of the control, 68 and 166%. PMNs functions are not altered by josamycin with the exception of an enhancement of the oxidative burst induced by formylmethionyl-leucyl-phenylalanine, a synthetic compound similar to bacterial derivatives. In conclusion, we have shown a synergic interaction between phagocytes and josamycin for the killing of bacteria resistant to this antibiotic (MiC greater than 128 mg/l). This could be due either to an alteration of some PMN membrane receptors or to alterations of bacteria which render them more sensitive to natural bactericidal mechanisms and/or more able to activate these mechanisms.

Blood Bactericidal Activity↗

PubMed1988

Influence of subinhibitory concentrations of ceftriaxone on opsonization and killing of Pseudomonas aeruginosa by human neutrophils.

Ceftriaxone, a 2-aminothiazolyl cephalosporin does not alter human neutrophil (PMN) bactericidal function. However, low concentrations of ceftriaxone induce some bacterial strains to be more sensitive to PMN killing. We have studied the effect of a subinhibitory concentration of ceftriaxone (10 mg/l) on Pseudomonas aeruginosa (MIC greater than 128 mg/l). After an overnight exposure to this concentration of ceftriaxone, P. aeruginosa elongated into filaments. PMN killing of ceftriaxone-treated bacteria was better than killing of control bacteria. This enhanced killing was correlated with an increased sensitivity to oxygen-dependent bacterial killing. Furthermore, the altered bacteria induced a greater oxidative response of PMN which was independent of their chemiluminescence response after stimulation by control P. aeruginosa. This increased oxidative burst was attributable to both non-opsonodependent stimulation and to increased deposit of opsonins.

Ceftriaxone↗

PubMed1988

Effects of amodiaquine, chloroquine, and mefloquine on human polymorphonuclear neutrophil function in vitro.

This study concerns the in vitro interaction with human polymorphonuclear neutrophils (PMNs) of amodiaquine, chloroquine, and mefloquine, three antimalarial drugs currently in use for the treatment and prophylaxis of malaria. It was found that mefloquine (100 and 50 micrograms/ml) significantly altered PMN viability while the other two drugs did not. Neutrophil chemotaxis was impaired by chloroquine (100 micrograms/ml) and mefloquine (greater than 10 micrograms/ml) but not by amodiaquine. Phagocytosis was decreased by about 50% in the presence of chloroquine (100 micrograms/ml) or mefloquine (10 micrograms/ml). The three antimalarial drugs altered neutrophil oxidative metabolism as assessed by luminol-amplified chemiluminescence. The strongest effect was observed with mefloquine, which abolished almost completely the neutrophil burst at concentrations of greater than 10 micrograms/ml whatever the stimulus used. This effect was not reversed by washing. Chloroquine and amodiaquine also impaired this PMN response by approximately 80 and 50%, respectively, but only at the highest concentration used (100 micrograms/ml). In the case of amodiaquine, the neutrophil response was restored by washing, except for stimulation with opsonized particles. After washing, the depressive effect of chloroquine was reversed completely in the case of phorbol myristate acetate stimulation and partly in the case of opsonized particle stimulation, but the formylmethionyl-leucyl-phenylalanine-induced response was not restored. These data show that although they are structurally related, amodiaquine and chloroquine exhibit qualitatively and quantitatively different depressive effects on PMN function and probably interfere at different points of cell activation, although the precise mechanisms are as yet unresolved.

Amodiaquine↗

PubMed1988

[Interaction of roxithromycin with human polymorphonuclear neutrophils in vitro and ex vivo].

Roxithromycin (RU 28965) a new semisynthetic macrolide has been reported to display an antibacterial spectrum and activity in vitro similar to those of others macrolides. However, roxithromycin seems more efficient than erythromycin in in vivo experimental infections (mice). We have previously reported that roxithromycin increases the ability of human neutrophils (PMN) for bactericidal activity (S. aureus) or phagocytosis (K. pneumoniae) in vitro without altering other PMN functional parameters. In this study, roxithromycin (single dose-300 mg) was given to 6 human volunteers. The neutrophils collected 90 min after ingestion display a significant increased ability to phagocytose and kill S. aureus and K. pneumoniae. Furthermore chemotaxis, oxidative burst and myeloperoxidase activity of the PMN after roxithromycin ingestion were enhanced compared to those of PMN before ingestion. This discrepancy between immunomodulating effect of roxithromycin in vitro and in vivo outlines the complexity of in vivo experimental models and requires further studies in vivo in particular in patients suffering from sepsis.

Adult↗

PubMed1987

Cefodizime (HR 221) potentiation of human neutrophil oxygen-independent bactericidal activity.

The enhanced bactericidal activity of human neutrophils induced by cefotaxime and cefodizime, two methoxy-imino-amino- 2-thiazolyl cephalosporins, is linked to the cell stimulation of oxygen-dependent and oxygen-independent killing systems, respectively. Cefotaxime enhances both the killing and the oxidative response of neutrophils to opsonized particulate stimuli (bacteria for both activities and opsonized zymosan for the oxidative burst). These effects were not observed with non-opsonized particles (bacteria or zymosan) or soluble stimuli. On the contrary, cefodizime enhances killing of opsonized and non-opsonized bacteria by neutrophils regardless of treatment with phenylbutazone which blocks neutrophil oxidative metabolism. Cefodizime does not universally alter the oxidative burst induced by various stimuli, but has been shown to enhance the bactericidal activity of crude extracts of neutrophil granules. The data suggest that cefodizime and non O2-dependent killing systems of neutrophils cooperate in killing bacteria.

Cefotaxime↗

PubMed1987

Interaction of ceftriaxone with human polymorphonuclear neutrophil function.

Ceftriaxone, an amino-2-thiazolyl cephalosporin, has been shown to cooperate in vitro with human neutrophils for the killing of some bacteria. In this work the direct interaction with human leucocyte bactericidal function has been studied. Ceftriaxone (1000 to 1 mg/l) did not alter neutrophil chemotaxis or superoxide anion production. It also did not interfere with the chemiluminescence response of isolated PMN although a paradoxical depressive effect was observed with whole human blood in the case of zymosan stimulation. The killing of Staphylococcus aureus and Klebsiella pneumoniae was not enhanced by ceftriaxone and phagocytosis was significantly depressed only with adherent neutrophils but not when using neutrophils in liquid medium. It is concluded that the synergy observed between leucocyte and ceftriaxone for bacterial killing cannot be related to a direct stimulation of neutrophil functions and should depend on bacterial alteration.

Blood Bactericidal Activity↗

PubMed1987

Effect of ceftriaxone-induced alterations of bacteria on neutrophil bactericidal function.

Two bacterial strains (Staphylococcus aureus and Klebsiella pneumoniae) were exposed to subinhibitory concentrations of ceftriaxone. After an overnight culture in presence of 1 MIC of ceftriaxone either in broth or on solid medium S. aureus showed enlarged forms which were better phagocytosed (increase about 40%) and killed (increase about 50%) than control staphylococci. Exposure of K. pneumoniae to 0.1 MIC ceftriaxone resulted in filamentation of bacteria. When grown in the presence of 0.01 MIC, K. pneumoniae did not elongate into filaments but were significantly more phagocytosed (increase about 40%) or killed (increase about 170%) than control bacilli. The mechanism of the greater sensitivity to PMN killing of the altered S. aureus and K. pneumoniae was assessed either with phenylbutazone-treated PMN or by in-vitro exposure to crude granule extracts of PMN. The altered bacteria displayed a significant susceptibility to the non-oxidative killing mechanism while untreated bacteria were unaffected by the non-oxidative system. These data could explain the synergy observed between ceftriaxone and leucocytes in the killing of some micro-organisms.

Blood Bactericidal Activity↗