Risk factors for and consequences of difficult fetal extraction in emergency caesarean section. A retrospective registry-based cohort study

INTRODUCTION

This study aimed to assess risk factors for difficult fetal extraction in emergency caesarean sections, focusing on top-up epidural anesthesia compared to spinal anesthesia. Additionally, this study addressed consequences of difficult fetal extraction on neonatal and maternal morbidity.

MATERIAL AND METHODS

This retrospective registry-based cohort study included 2,332 of 2,892 emergency caesarean sections performed with local anesthesia during 2010-2017. Main outcomes were analyzed by crude and multiple adjusted logistic regression providing odds ratios.

RESULTS

Difficult fetal extraction was found in 14.9% of emergency caesarean sections. Risk-factors for difficult fetal extraction included top-up epidural anesthesia (aOR:1.37[95 %CI 1.04-1.81]), high pre-pregnancy BMI (aOR:1.41[95 %CI 1.05-1.89]), deep fetal descent (ischial spine: aOR:2.53[95 %CI 1.89-3.39], pelvic floor: aOR:3.11[95 %CI 1.32-7.33]), and anterior placental position (aOR:1.37[95 %CI 1.06-1.77]). Difficult fetal extraction was associated with increased risk of low umbilical artery pH 7.00-7.09 (aOR:3.50[95 %CI 1.98-6.15]) pH ≤ 6.99 (aOR:4.20[95 %CI 1.61-10.91]), five-minute Apgar score ≤ 6 (aOR:3.41[95 %CI 1.49-7.83]) and maternal blood loss (501-1,000 ml: aOR:1.65[95 %CI 1.27-2.16], 1,001-1,500 ml: aOR:3.24[95 %CI 2.24-4.67], 1,501-2,000 ml: aOR:3.94[95 %CI 2.24-6.94] and ≥ 2001 ml: aOR:2.76[95 %CI 1.12-6.82]).

CONCLUSION

This study identified four risk factors for difficult fetal extraction in emergency caesarean section: top-up epidural anesthesia, high maternal BMI, deep fetal descent and anterior placental position. Additionally, difficult fetal extraction was associated with poor neonatal and maternal outcomes.

Induction of labor with high- or low-dosage oral misoprostol-A Danish descriptive retrospective cohort study 2015-16

INTRODUCTION

In Denmark, the rate of induced labor from 37 gestational weeks has increased by 108% from 12.4% in 2000 to 25.1% in 2012, and today more than 1 in 4 deliveries are induced. Standard procedure at North Zealand Hospital changed in 2016 from a dosage of 50 µg oral misoprostol 2-3 times daily, to 25 µg up to 8 times daily. Also, since 2016 healthy women with uncomplicated pregnancies (primiparous and multiparous) have been offered induction as an outpatient procedure. This study aimed to compare the current low-dosage procedure (25 µg) with the former high-dosage procedure (50 µg) in terms of induction to delivery time, maternal and fetal outcomes, and risk of uterine hyperstimulation.

MATERIAL AND METHODS

Data from June 2015 to October 2016 were included. Comparable baseline, demographic, and obstetric data for women induced according to high-dosage or low-dosage protocols were retrieved from local medical files. Descriptive statistics, Pearson's chi-squared tests, Kaplan-Meier survival estimates, and logistic regression analyses were performed.

RESULTS

The study included 816 induced deliveries. The high- and low-dosage groups differed in rates of plurality and place of induction. Induction to delivery times lasting longer than 72 hours were significantly decreased in the low-dosage group (adjusted odds ratio [aOR] 0.48, 95% confidence interval [95% CI] 0.27 to 0.86). Women in the low-dosage group also less often needed additional induction (P = 0.02), and the rate of uterine hyperstimulation was low irrespective of protocol (1% vs 3%, P = 0.16). There were no cases of uterine rupture in either group. The probability of vaginal delivery in the low-dosage group increased (adjusted hazard ratio 1.27, 95% CI 1.08 to 1.49), as did the risk of delivery with vacuum extraction (aOR 2.27, 95% CI 1.24 to 4.15), whereas delivery by cesarean section slightly decreased (aOR 0.89, 95% CI 0.59 to 1.33). The risk of meconium-stained liquor was nonsignificantly decreased (aOR 0.82, 95% CI 0.55 to 1.23).

CONCLUSIONS

The low-dosage induction protocol was associated with favorable obstetric outcomes in terms of increased probability of vaginal delivery, but with higher risk of vacuum extraction. Protracted inductions and additional nonmedical interventions were reduced. There were no cases of uterine rupture. Statistically nonsignificant, the risk of uterine hyperstimulation was increased whereas the risk of meconium-stained liquor and of cesarean section was slightly decreased.

Streptolysin O II. Relationship of Sulfyhdryl Groups to Activity

Streptolysin O (SO), a group A streptococcal toxin, exists in two forms, a reduced active state and an oxidized reversibly inactive state. Activity is measured by red blood cell hemolysis. SO is a labile toxin, and, with time, activity is irreversibly lost. The rate of activity loss is slowed by incubation with 0.1 m 2-mercaptoethanol or 0.01 m ethylenediaminetetraacetic acid (EDTA). The effect of EDTA can be reversed by excess MgSO(4). Reversibly oxidized SO is activated by cleavage of disulfide bonds. When the free sulfhydryl groups of the active SO are alkylated with iodoacetamide, complete and irreversible loss of activity results. Periodate (0.01 m) oxidation also causes complete loss of activity which may be due to oxidation of sulfhydryl groups. SO in the active form reacts with Fe(2+), Cu(2+), Ca(2+), and Mg(2+), causing loss of activity in various degrees depending on the ions and the concentration used. Ferric and cupric ions are most effective and cause loss of activity at concentrations on the order of 10(-4)m. The reversibly oxidized form of SO is not influenced by exposure to cupric ions (0.01 m), indicating that the reaction is only with the active form of SO, probably involving the free sulfhydryl groups. These groups may be responsible for the direct binding of the toxin to the target membrane or for the maintenance of the proper conformation for activity.

Antibiotics versus placebo for prevention of postoperative infection after appendicectomy

BACKGROUND

Appendicitis is the most common cause of acute abdominal pain requiring surgical intervention. The cause of appendicitis is unclear and the mechanism of pathogenesis continues to be debated. Despite improved asepsis and surgical techniques, postoperative complications, such as wound infection and intraabdominal abscess, still account for a significant morbidity. Several studies implicate that postoperative infections are reduced by administration of antimicrobial regimes.

OBJECTIVES

This review evaluated the use of antibiotics compared to placebo or no treatment in patients undergoing appendectomy. Will these patients benefit from antimicrobial prophylaxis? The outcomes were described according to the nature of the appendix, as either simple appendicitis (including the non-infectious stage) and complicated appendicitis. The efficacy of different antibiotic regimens were not evaluated.

SEARCH STRATEGY

We searched The Cochrane Central Register of Controlled Trials (Cochrane Library 2005 issue 1); Pubmed ; EMBASE; and the Cochrane Colorectal Cancer Group Specialised Register (April 2005). In addition, we manually searched the reference lists of the primary identified trials.

SELECTION CRITERIA

We evaluated Randomised Controlled Trials (RCTs) and Controlled Clinical Trials (CCTs) in which any antibiotic regime were compared to placebo in patients suspected of having appendicitis, and undergoing appendectomy. Both studies on children and adults were reviewed. The outcome measures of the studies were: Wound infection, intra abdominal abscess, length of stay in hospital, and mortality.

DATA COLLECTION AND ANALYSIS

Eligibility and trial quality were assessed, recorded and cross-checked by two reviewers.

MAIN RESULTS

Forty-five studies including 9576 patients were included in this review. The overall result is that the use of antibiotics is superior to placebo for preventing wound infection and intraabdominal abscess, with no apparent difference in the nature of the removed appendix. Studies exclusively on children and studies examining topical application reported results in favour to the above, although the results were not significant.

AUTHORS' CONCLUSIONS

Antibiotic prophylaxis is effective in the prevention of postoperative complications in appendectomised patients, whether the administration is given pre-, peri- or post-operatively, and could be considered for routine in emergency appendectomies.

Antibiotics versus placebo for prevention of postoperative infection after appendicectomy

BACKGROUND

Appendicitis is the most common cause of acute abdominal pain requiring surgical intervention. The cause of appendicitis is unclear and the mechanism of pathogenesis continues to be debated. Despite improved asepsis and surgical techniques, postoperative complications, such as wound infection and intraabdominal abscess, still account for a significant morbidity. Several studies implicate that postoperative infections are reduced by administration of antimicrobial regimes.

OBJECTIVES

The objective of this review is to evaluate the use of antibiotics with placebo or no treatment in patients undergoing appendectomy. Will these patients benefit from antimicrobial prophylaxis? The outcomes are described according to the nature of the appendix, as either simple appendicitis (including the non-infectious stage) and complicated appendicitis. This review do not attempt to compare the effect of different regimens. That clinical question is addressed in another review undertaken by Bleuer 1999.

SEARCH STRATEGY

We searched The Cochrane Controlled Trials Register (Cochrane Library 2002 issue 4); Pubmed, Embase and the Cochrane Colorectal Cancer Group Specialised Register (Up to October 2002). In addition we manually searched the reference lists of the primary identified trials.

SELECTION CRITERIA

We evaluated Randomised Controlled Trials (RCTs) and Controlled Clinical Trials (CCTs) in which any antibiotic regime were compared to placebo in patients suspected of having appendicitis, and undergoing appendectomy. Both studies on children and adults were reviewed. The outcome measures of the studies were: Wound infection, intra abdominal abscess, length of stay in hospital, and mortality.

DATA COLLECTION AND ANALYSIS

Eligibility and trial quality were assessed, recorded and cross-checked by two reviewers.

MAIN RESULTS

Forty-five studies including 9576 patients were included in this review. The overall result is that the use of antibiotics is superior to placebo for preventing wound infection and intraabdominal abscess, with no apparent difference in the nature of the removed appendix. Studies exclusively on children and studies examining topical application reported results in favour to the above although the results were not significant.

REVIEWER'S CONCLUSIONS

Antibiotic prophylaxis is effective in the prevention of postoperative complications in appendectomised patients, whether the administration is given pre-, peri- or post-operatively, and could be considered for routine in emergency appendectomies.

Heparins and mechanical methods for thromboprophylaxis in colorectal surgery

BACKGROUND

Colorectal surgery implies higher risk of postoperative thromboembolic complications as deep venous thrombosis (DVT) and pulmonary embolism (PE) than general surgery. The best prophylaxis in general surgery is heparin and graded compression stockings. No systematic review on combination prophylaxis or on thrombosis prophylaxis in colorectal surgery has been published.

OBJECTIVES

To compare the incidence of postoperative thromboembolism after colorectal surgery using prophylactic methods focussing on heparins and mechanical methods alone and in combinations.

SEARCH STRATEGY

Electronic searches was performed in MEDLINE, EMBASE back to 1970. Abstract books from major congresses were handsearched as were reference lists from previously performed reviews.

SELECTION CRITERIA

RCT or CCT comparing prophylactic interventions and/or placebo. Outcomes were ascending venography, 125 I-fibrinogen uptake test, ultrasound methods, pulmonary scintigraphy. Studies, using thermographic methods, other isotopic methods, plethysmographic methods, and purely clinical methods as the only diagnostic measure were excluded. 558 studies were identified - 477 were excluded. Only 3 of the identified studies focused exclusively on colorectal surgery. Studies of general surgery contain considerable numbers of colorectal patients. The authors of 66 studies in general and/or abdominal surgery were contacted for retrieving the results from the colorectal patients. Answers were received from very few. 19 studies entered this review.

DATA COLLECTION AND ANALYSIS

All studies and all data extraction were performed independently by at least two of the authors. Outcome was deep venous thrombosis and/or pulmonary embolism. Analysis of bleeding complications were unfeasible. 12 meaningful outcomes were analysed by means of the fixed effects model with Peto Odds Ratios.

MAIN RESULTS

Heparins versus no treatment: Any kind of heparincompared to no treatment or placebo (comparison 07.03, 11 studies). Heparin is better in preventing DVT and/or PE with a Peto Odds ratio at 0.32 (95% Confidence Interval 0.20-0.53) Unfractionated heparin versus low molecular weight heparin (comparison 08.03, 4 studies). The two treatments were found equally effective in preventing DVT and/or PE with a Peto Odds ratio 1.01 (95% Confidence Interval 0.67-1.52). Mechanical methods (comparison 10.3, 2 studies). The combination of graded compression stockings and LDH is better than LDH alone in preventing DVT and/or PE with a Peto Odds ratio at 4.17 (95% Confidence Interval 1.37-12.70).

REVIEWER'S CONCLUSIONS

The optimal prophylaxis in colorectal surgery is the combination of graduated compression stockings and low-dose unfractionated heparin. The unfractionated heparin can be replaced with low molecular weight heparin.

Mycobacterium avium induces HIV upregulation through mechanisms independent of cytokine induction

Mycobacterium avium complex (MAC) can induce upregulation of HIV. To investigate the underlying mechanisms, the effect of MAC-induced cytokines on HIV replication was first studied. Semiquantitative RT-PCR, followed by Northern blot analysis, revealed that mRNA encoding IL-6 and TNF-alpha was induced by MAC. However, production of these cytokines was undetectable and the addition of anti-cytokine antibodies to coinfected cells could only minimally block the MAC effect on HIV. Infection of U38 cells with MAC resulted in enhancement of HIV-1 LTR-CAT transcription. In addition, transient transfection of U937 cells with full-length wild-type as well as NF-kappaB-binding site-deleted mutant HIV-1 LTR-CAT constructs revealed that MAC-induced HIV-LTR CAT is NF-kappaB dependent. These findings, together with our previous work, indicate that MAC-induced cytokine expression increases the formation of NF-kappaB, which in turn enhances HIV-1 LTR-CAT transcription. However, additional factor(s) yet to be elucidated may play a more significant role in MAC-mediated HIV-upregulation.

Biodegradable implants from poly-(alpha-hydroxy acid) polymers for isoniazid delivery

SETTING

In vitro and in vivo study of an isoniazid (INH) drug delivery system.

OBJECTIVE

To develop a system for the treatment of tuberculosis using a subcutaneous polymer implant with a large drug load released slowly over a long period. INH delivery by biodegradable poly-(alpha-hydroxy acid) polymers was evaluated using ground polymer and compression molded implants.

DESIGN

Rate of drug release and structural stability of the implant in an aqueous environment were measured, as were in vivo evaluations of the duration of measurable levels of INH in serum and urine.

RESULTS

Factors that influenced the suitability of an implant in an in vitro system included polymer molecular weight and crystallinity, polymer and drug particle size, drug loading dose, and press temperature and pressure. The implant characteristics that most closely approached optimal conditions include a polymer of 100% L-lactide with low intrinsic viscosity, polymer particle size <75 micron, and INH particle = 126-180 micron, INH loading dose not to exceed 46%, and press conditions of 70 degrees C and 345000 kPa. Studies of subcutaneous implants in rabbits and baboons show that INH is released from the implant for 15 to 26 weeks.

CONCLUSIONS

An INH-containing polymer was developed that was structurally stable in an aqueous environment and that released INH over a period of at least 15 weeks. Studies with infected animals will be necessary to determine the dose required for prophylaxis and treatment of active disease.

Mycobacterium avium complex activates nuclear factor kappaB via induction of inflammatory cytokines

A variety of microorganisms has been reported to directly induce NF-kappaB, a critical step in the regulation of genes involved in the cellular immune response. In this study, we demonstrate that proinflammatory cytokines such as tumor necrosis factor alpha (TNFalpha) produced upon activation by the Mycobacterium avium complex (MAC) preceed NF-kappaB activity in U937, a human monocytoid cell line. MAC induction of TNFalpha mRNA expression was detected within 15 min after MAC infection, whereas enhanced NF-kappaB binding activity was not detected until 90 to 120 min postinfection. Supershift analysis revealed increased p50 in the MAC-induced NF-kappaB binding complexes. Consistent with an autocrine mechanism, anti-TNFalpha antibody and dexamethasone, a known cytokine inhibitor, both completely suppressed the effect of MAC on the induction of NF-kappaB. Taken together, these findings suggest that exposure of monocyte cell membranes to MAC induces endogenous TNFalpha, which in turn enhances NF-kappaB binding activity. The rapid induction of TNFalpha may be important in the initial host response to MAC infection.

Information processing and antiretroviral therapy in HIV-1 infection

Computerized reaction time (RT) tasks are sensitive measures of subclinical HIV-related mental slowing. We previously reported that nondemented HIV-seropositive patients on antiretroviral therapy at the time of testing had faster choice RTs compared to matched untreated seropositive participants. In the present study, we evaluated the performance of 163 nondemented HIV-seropositive participants on a reaction time version of the Stroop task as a function of antiretroviral status. Persons on antiretroviral therapy at the time of testing had significantly faster reaction times than untreated individuals, although treated asymptomatic participants showed significantly less Stroop interference than treated symptomatic participants. These effects could not be attributed to differences in demographic variables, disease status, substance abuse, or psychological distress. These data indicate that central information processing is faster for patients treated with antiretroviral compounds compared to untreated patients, and suggest that reaction time tasks may have significant potential utility in clinical trials of neuroprotective compounds.

[Prostate-specific antigen, acid phosphatases and rectal exploration in the diagnosis of prostatic cancer]

Eleven hundred and seven patients referred for urological evaluation including measurement of serumprostate specific antigen (PSA) measurement are reviewed. Prostate cancer was diagnosed in 105 patients. PSA was found to be superior to prostatic acid phosphatase in the discrimination between prostate cancer and benign prostatic conditions. In 105 patients with newly diagnosed prostate cancer, scintigraphic evidence of osseous metastases was found in thirty-seven. No patients with a serum PSA value less than three times the upper normal limit of the assay had a positive bone scan. Isotope bone scan can be omitted in these patients, if they are not considered candidates for curative treatment.

Transcriptional regulation of hydroxypyruvate reductase gene expression by cytokinin in etiolated pumpkin cotyledons

To understand the mechanisms by which the expression of a specific gene is modulated by cytokinin, the regulation of hydroxypyruvate reductase (HPR) transcript levels by N6-benzyladenine (BA) in etiolated pumpkin (Cucurbita pepo L. cv. Halloween) cotyledons was investigated. A pumpkin HPR cDNA was generated by reverse transcriptase-polymerase chain reaction and its nucleotide sequence was determined. An antisense HPR RNA was prepared for RNase protection analysis of HPR-mRNA expression patterns in the cotyledons of dark-grown pumpkin seedlings. Treatment of the cotyledons with BA was shown to modulate HPR mRNA levels in a dose- and time-dependent manner. Similarly, nuclear run-on studies showed that the rate of transcription was also enhanced by BA treatment of the cotyledons. These results suggest that the enhancement of HPR mRNA by cytokinin is, at least in part, at the level of transcription.

Human immunodeficiency virus and Mycobacterium avium complex coinfection of monocytoid cells results in reciprocal enhancement of multiplication

Disseminated Mycobacterium avium complex (MAC) infection is an important opportunistic infection in AIDS patients. Because cells of macrophage lineage are targets for both human immunodeficiency virus (HIV) and MAC, the monocytoid cell line U937 was coinfected with both pathogens. Coinfected cultures had increased HIV replication (more than threefold at day 6) and an increased percentage of HIV-infected cells compared with cultures infected only with HIV. The kinetics of HIV replication were significantly increased in this coinfection system as measured by flow cytometry. When cells were infected concurrently, the rate of intracellular growth of MAC was not significantly affected. However, cells preinfected with HIV before infection with MAC showed significant enhancement of MAC growth compared with control cells. The kinetics of cell death were also increased in the coinfection system compared with singly infected controls. Thus, coinfection of monocytoid cells with HIV and MAC in vitro results in reciprocal enhancement of multiplication.

Isolated myocardial abscess causing coronary artery rupture and fatal hemopericardium

We report a rare case of cardiac tamponade caused by hemopericardium secondary to erosion and rupture of a coronary artery by an adjacent solitary myocardial abscess. The resulting tamponade led to the sudden death of this 46-year-old man. Antemortem blood culture and the postmortem microscopic examination of the myocardial abscess revealed the causative agent to be Staphylococcus aureus. Hemopericardium due to ventricular wall rupture secondary to a myocardial abscess has been infrequently reported, but, to our knowledge, only one other report of hemopericardium due to coronary artery rupture related to myocardial abscess has been published.

Depressed neutrophil superoxide production in human immunodeficiency virus infection

Neutrophil (PMNL) superoxide (O2-) production was evaluated in 71 patients with human immunodeficiency virus (HIV) infection at different stages of disease. In vitro O2- production was significantly depressed for PMNL isolated from HIV-positive patients compared with control PMNL at rest and after stimulation. The degree of impairment of O2- production was more pronounced for patients with lower absolute CD4+ lymphocyte counts. Antiretroviral therapy with zidovudine was also associated with impaired O2- production, but this may reflect a longer duration of disease for treated patients. Zidovudine had no direct inhibitory effect on O2- production by control PMNL in vitro, and serial measurements of O2- production by PMNL from patients before and after initiation of zidovudine did not demonstrate an in vivo inhibitory effect. Impaired PMNL oxidative metabolism in HIV infection may contribute to the increased risk of serious bacterial infections, certain opportunistic infections, and perhaps the pathogenesis of HIV infection itself.

Human platelet antigen-1 (Zw) typing using PCR-RFLP

The agreement between human platelet antigen-1 typing with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and typing with a serological ELISA method was evaluated. A total of 82 individuals were typed and an absolute correlation was found between the two typing methods. The PCR-RFLP typing method could be clinically useful in a number of immunologically mediated platelet disorders, characterized by severe thrombocytopenia and in early prenatal diagnosis of neonatal alloimmune thrombocytopenia, in which serological methods are difficult to apply because of their dependency on access to platelets and access to well-characterized anti-HPA-1b antisera.

Kinetics of CD11b expression on neutrophils isolated from subjects with healthy gingivae and patients with advanced periodontitis

The adhesion molecule, CD11b/CD18, plays a role in host defense against bacterial infections owing to its involvement in cell migration and phagocytosis. We examined the kinetics of CD11b expression on neutrophils isolated from peripheral blood (PB-PMNs) and gingival crevicular fluid (CF-PMNs) in subjects with healthy gingivae and in patients with advanced periodontitis in order to assess if CF-PMNs respond differently in regard to CD11b expression from PB-PMNs isolated from healthy or periodontitis subjects. CF-PMNs or formylmethionylleucylphenylalanine (fMLP)-stimulated PB-PMNs were incubated in buffer with or without divalent cations for 60, 90, or 110 minutes. Plasma membrane (surface) CD11b as measured by flow cytometry was found to be reduced with time when cells (PB-PMNs or CF-PMNs) from either controls or patients were treated with calcium- and magnesium-free buffer. However, when CF-PMNs were treated with buffer containing Ca++/Mg++, surface CD11b expression increased on cells from both controls and patients. The reduction in CD11b expression on PB-PMNs is significantly greater than that measured on CF-PMNs over time. Therefore, CF-PMNs respond differently from PB-PMNs which have been artificially stimulated with fMLP in regard to kinetics of CD11b expression on the plasma membrane.

Benzodiazepines inhibit neutrophil chemotaxis and superoxide production in a stimulus dependent manner; PK-11195 antagonizes these effects

Diazepam, which binds both central (neuronal) and peripheral (non-neuronal) benzodiazepine binding sites, and Ro5-4864, a ligand selective for benzodiazepine peripheral binding sites (PBS), both inhibited the FMLP induced chemotaxis in human neutrophils at concentrations as low as 10(-8) M. A selective peripheral benzodiazepine antagonist, PK-11195 (10(-5) M), partially reversed the benzodiazepine inhibition of chemotaxis. Diazepam also inhibited the superoxide production induced by FMLP, NaF, and A23187, but not that induced by PMA whose stimulant action was insensitive even to 10(-4) M diazepam. The FMLP-induced superoxide production was most sensitive to diazepam inhibition (ID50 = 2.25 x 10(-6) M diazepam); the effect of NaF was slightly less sensitive (ID50 = 1.34 x 10(-5) M diazepam); and the effect of A23187 was least sensitive as it was suppressed only at 10(-4) M diazepam concentrations. Like diazepam, Ro5-4864 inhibited the FMLP-induced superoxide production, and PK-11195 (10(-5) M) significantly antagonized both diazepam and Ro5-4864 inhibition. Binding studies showed the presence of a saturable benzodiazepine 'peripheral' type binding site (PBS) on human neutrophils with a Kd of 1.2 +/- 0.06 x 10(-8) M (+/- SEM), and a Bmax of 1028 +/- 86.2 fmol/10(6) cells (+/- SEM) for [3H]Ro5-4864; the binding was displaceable by PK-11195, Ro5-4864 and diazepam but not by clonazepam.

Activation of human neutrophils by Mycobacterium tuberculosis-derived sulfolipid-1

The principal sulfatide of a group of acidic lipids from virulent Mycobacterium tuberculosis, sulfolipid-1 (SL-1), stimulates neutrophil superoxide (O2-) generation and, at lower concentrations, primes neutrophil response to several other metabolic agonists including FMLP, and PMA. These responses to SL-1 were examined in relation to diacylglycerol (DAG) generation, Ca2+ availability and activation of guanine nucleotide binding proteins to clarify the signal transduction pathways involved. Pertussis toxin inhibited the ability of SL-1 to both stimulate neutrophils directly and to prime neutrophils for subsequent responses induced by PMA, suggesting a role for one or more guanine nucleotide regulating proteins in both responses. SL-1 induced a rise in neutrophil DAG levels. DAG generation was inhibited by pretreatment of cells with pertussis toxin. Depletion of extracellular Ca2+ ablated O2- release induced by stimulatory levels of SL-1 but did not inhibit the priming effect induced by substimulatory concentrations of the lipid. Investigation of the activation of the neutrophil NADPH oxidase in a cell-free system revealed that the SL-1-priming effect was associated with translocation of the soluble cytosolic factors required for activation of the enzyme. Cytosolic factor translocation was not observed in pertussis toxin pretreated cells. Our results provide evidence for the role of a guanine nucleotide binding protein in both priming and direct activation of neutrophils by SL-1. This G protein regulates both SL-1-induced DAG generation and cytosolic cofactor translocation involved in neutrophil activation and priming. The multiplicity of effects of SL-1 on signal transduction pathways leading to phagocyte activation and priming may exert a profound influence on the pathogenicity of M. tuberculosis.

Activation of human neutrophils by Mycobacterium tuberculosis-derived sulfolipid-1

The principal sulfatide of a group of acidic lipids from virulent Mycobacterium tuberculosis, sulfolipid-1 (SL-1), stimulates neutrophil superoxide (O2-) generation and, at lower concentrations, primes neutrophil response to several other metabolic agonists including FMLP, and PMA. These responses to SL-1 were examined in relation to diacylglycerol (DAG) generation, Ca2+ availability and activation of guanine nucleotide binding proteins to clarify the signal transduction pathways involved. Pertussis toxin inhibited the ability of SL-1 to both stimulate neutrophils directly and to prime neutrophils for subsequent responses induced by PMA, suggesting a role for one or more guanine nucleotide regulating proteins in both responses. SL-1 induced a rise in neutrophil DAG levels. DAG generation was inhibited by pretreatment of cells with pertussis toxin. Depletion of extracellular Ca2+ ablated O2- release induced by stimulatory levels of SL-1 but did not inhibit the priming effect induced by substimulatory concentrations of the lipid. Investigation of the activation of the neutrophil NADPH oxidase in a cell-free system revealed that the SL-1-priming effect was associated with translocation of the soluble cytosolic factors required for activation of the enzyme. Cytosolic factor translocation was not observed in pertussis toxin pretreated cells. Our results provide evidence for the role of a guanine nucleotide binding protein in both priming and direct activation of neutrophils by SL-1. This G protein regulates both SL-1-induced DAG generation and cytosolic cofactor translocation involved in neutrophil activation and priming. The multiplicity of effects of SL-1 on signal transduction pathways leading to phagocyte activation and priming may exert a profound influence on the pathogenicity of M. tuberculosis.

Effect of glucocorticoids and interferon-gamma on the oxidative responses of monocytes from leprosy patients and normal donors

Leprosy patients suffering from erythema nodosum leprosum are frequently treated with glucocorticosteroids. The role glucocorticosteroids and interferon-gamma (IFN-gamma) play in regulating the interaction of phagocytic cells with Mycobacterium leprae was examined. Monocytes from leprosy patients receiving prednisone therapy responded to lower concentrations of IFN-gamma in vitro with enhanced superoxide anion release when challenged with M. leprae or M. bovis BCG than did monocytes from healthy subjects and other leprosy patients. Although the number of patients was small and the population heterogeneous, the data suggested that prednisone could alter IFN-gamma efficacy and led to the examination of the effect of glucocorticosteroids on IFN-gamma activation of monocytes. IFN-gamma treatment following in vitro dexamethasone pretreatment of monocytes from healthy subjects resulted in a greater enhancement of superoxide anion generation than that observed with IFN-gamma treatment alone. These findings are important considerations in evaluating patient immune function because IFN-gamma is being used in a number of clinical trials with leprosy patients.

CD11b expression on neutrophils in human crevicular fluid collected from clinically healthy gingivae

This study investigated the cell surface expression of CD11b (Mo 1, Mac-1, CR 3) by neutrophils (PMNs) from human crevicular fluid (CF-PMNs). CD11b expression on CF-PMNs was compared, using flow cytometry, to that on peripheral blood PMNs (PB-PMNs) isolated simultaneously from the same subjects. CD11b expression by CF-PMNs was also compared to that on PB-PMNs stimulated with formylmethionylleucylphenylalanine (fMLP) or crevicular fluid supernatant (cell-free portion of CF diluted with buffer) (CFS). Crevicular PMNs consistently expressed more CD11b than unstimulated PB-PMNs (p less than 0.001). The level of CD11b expressed on these CF-PMNs was significantly greater than that expressed by PB-PMNs stimulated with 10(-8) M fMLP (p less than 0.05). The level of CD11b surface expression on CF-PMNs was not statistically different from that expressed on PB-PMNs stimulated with CFS or 10(-6) M fMLP. However, CFS significantly stimulated upregulation of surface CD11b expression on PB-PMNs relative to that achieved with 10(-8) M fMLP (0.01 less than p less than or equal to 0.025). Thus it is concluded that CF-PMNs express a high level of CD11b and CFS can upregulate CD11b expression on PB-PMNs to a level that is at least as great as that achieved with 10(-8) M fMLP.

Analysis of neutrophil chemotaxis and CD11b expression in pre-pubertal periodontitis

The objectives of this study were to (1) determine chemotaxis (CX) response by neutrophils (PMNs) isolated from patients with the localized form of pre-pubertal periodontitis (L-PP) and compare these responses with those of age-matched and adult controls, (2) determine the level and up-regulation of CD11b expression upon stimulation with fMLP by peripheral blood PMNs (PB-PMNs) isolated from patients with L-PP and compare these levels with those of age-matched and adult controls, and (3) determine whether there is a correlation between CX and CD11b expression (up-regulation) by PB-PMNs. PB-PMNs from a total of seven patients with L-PP, seven age-matched pediatric controls, and 11 adult controls (four adults for both CD11b and CX assays, and seven adults for CX assays only) were analyzed for CX and CD11b expression. Direct immunofluorescence staining of CD11b was performed with FITC-conjugated monoclonal antibody. Flow cytometry was used to analyze stained cells for their fluorescence intensity. Chemotaxis activity in response to 10(-8) mol/L fMLP was examined in micro-well chemotaxis chambers. The results indicated that CX of PMNs from both L-PP patients and pediatric control subjects was significantly decreased, compared with that of normal adult control subjects (p less than 0.001). There was no significant difference between CX of PMNs from L-PP patients and that from normal pediatric controls (p greater than 0.7). CD11b expression did not significantly differ among L-PP patients, normal pediatric controls, and adult controls.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of monocyte oxidative responses in leprosy patients and healthy subjects as influenced by mycobacterial lipid pretreatment

Superoxide anion (O2-) release by monocytes from leprosy patients in a paired study was lower than that released by monocytes from healthy controls. Pretreatment of healthy control monocytes with phenolic glycolipid-I (PGL-I) of Mycobacterium leprae resulted in the release of less O2- than released by buffer-treated cells or cells pretreated with structurally similar lipids. However, pretreatment of patient monocytes with PGL-I did not affect the O2- generation, perhaps because the cells already had a lower capacity to produce O2-. Upon further examination of the data from the patient population, monocytes from lepromatous patients released significantly less O2- than cells from normal controls, while tuberculoid patient cells released O2- in amounts similar to that generated by cells from normal controls. In addition, monocytes from patients with a high bacterial index had a lower capacity to generate O2- when compared to cells from healthy individuals.

Killing of Mycobacterium tuberculosis by neutrophils: a nonoxidative process

To determine the role of oxygen radicals in the killing of Mycobacterium tuberculosis by neutrophils, the effects of free-radical inhibitors and enzymes, catalase, superoxide dismutase, taurine, deferoxamine, and histidine were evaluated. Changes in the viability of M. tuberculosis were determined by agar plate colony counts and a radiometric assay. No impairment in killing was seen with any of the inhibitors or enzymes. Patients with chronic granulomatous disease (CGD) have a defect in the NADPH oxidase pathway, causing their neutrophils to be unable to generate oxygen radicals. If these radicals are involved in killing, then CGD neutrophils should be less effective killers of M. tuberculosis than normal neutrophils. There was no evidence by either measure of M. tuberculosis viability that CGD neutrophils were less bactericidal than normal neutrophils. Killing by normal neutrophils was also effective in the absence of serum. These results lead to the conclusion that the mechanism by which M. tuberculosis is killed by neutrophils is independent of the oxygen metabolic burst.

Suppression of monocyte oxidative response by phenolic glycolipid I of Mycobacterium leprae

Mycobacterium leprae synthesizes a unique phenolic glycolipid (PGL-I) in abundant quantities. We studied the effect of PGL-I on the generation of superoxide anion (O2-) by stimulated human monocytes. Peripheral blood monocytes pretreated with PGL-I released less O2- when stimulated with M. leprae than did control monocytes. Monocytes pretreated with dimycocerosyl phthiocerol, mycoside A of Mycobacterium kansasii, or mycoside B of Mycobacterium microti, on the other hand, released O2- in quantities comparable to control monocytes in response to M. leprae stimulation. Monocyte O2- release in response to other stimuli of the oxidative metabolic burst, such as PMA, zymosan, Mycobacterium bovis Bacille Calmette-Guérin, or M. kansasii, was unaffected by lipid pretreatment. These findings demonstrate that PGL-I has a direct effect on monocyte O2- generation in response to M. leprae and suggest that PGL-I is a modulator of phagocytic cell function.

Suppression of monocyte oxidative response by phenolic glycolipid I of Mycobacterium leprae

Mycobacterium leprae synthesizes a unique phenolic glycolipid (PGL-I) in abundant quantities. We studied the effect of PGL-I on the generation of superoxide anion (O2-) by stimulated human monocytes. Peripheral blood monocytes pretreated with PGL-I released less O2- when stimulated with M. leprae than did control monocytes. Monocytes pretreated with dimycocerosyl phthiocerol, mycoside A of Mycobacterium kansasii, or mycoside B of Mycobacterium microti, on the other hand, released O2- in quantities comparable to control monocytes in response to M. leprae stimulation. Monocyte O2- release in response to other stimuli of the oxidative metabolic burst, such as PMA, zymosan, Mycobacterium bovis Bacille Calmette-Guérin, or M. kansasii, was unaffected by lipid pretreatment. These findings demonstrate that PGL-I has a direct effect on monocyte O2- generation in response to M. leprae and suggest that PGL-I is a modulator of phagocytic cell function.

Effect of Mycobacterium tuberculosis-derived sulfolipid I on human phagocytic cells

Experiments were performed to determine the effects of Mycobacterium tuberculosis-derived sulfolipid I on phagocytic cells. Sulfolipid I was taken up in significant amounts by human neutrophils and in lesser amounts by monocytes and lymphocytes. Superoxide (O2-) production by neutrophils was significantly increased by sulfolipid I, but the rate of production was slower than that reported previously for other stimuli. The optimal concentration of sulfolipid I for stimulation of O2- production was 27 micrograms/ml, while higher concentrations produced less. At substimulatory levels sulfolipid I caused enhancement of O2- release from neutrophils when it was subsequently stimulated by other agents. Nonadherent monocytes from most normal donors failed to produce O2- when treated with sulfolipid I; however, adherent monocytes pretreated with gamma interferon did produce O2- with sulfolipid I stimulation. Priming for an enhanced oxidative response of activated monocytes was also observed. These sulfolipid I-induced changes in phagocytic cell function may be important in altering the ability of phagocytes to respond effectively to M. tuberculosis and may also cause exaggerated inflammatory responses.

Human phagocytic cell responses to Mycobacterium leprae and Mycobacterium bovis Bacillus Calmette-Guérin. An in vitro comparison of leprosy vaccine components

Components of current vaccines for Hansen's disease include Mycobacterium bovis Bacillus Calmette-Guérin (BCG) and killed Mycobacterium leprae. BCG infections in humans are rare and most often occur in immune-compromised individuals. M. leprae on the other hand, although not causing clinical disease in most exposed individuals, is capable of infecting and replicating within mononuclear phagocytes. Lymphocytes from patients with the lepromatous form of Hansen's disease exhibit defective lymphokine production when challenged in vitro with M. leprae. This may result in inefficient mononuclear phagocyte activation for oxidative killing. To study the ability of normal phagocytes to ingest and respond oxidatively to BCG and M. leprae, we measured phagocytic cell O2- release and fluorescent oxidative product formation and visually confirmed the ingestion of the organisms. BCG stimulated a vigorous O2- generation in neutrophils and monocytes and flow cytometric oxidative product generation by neutrophils occurred in the majority of cells. M. leprae, stimulated a weak but significant O2- release requiring a high concentration of organisms and long exposure. By flow cytometric analysis, most neutrophils were able to respond to both organisms with the generation of fluorescent oxidative products. Neutrophil oxidative responses to M. leprae were substantially less than responses seen from neutrophils exposed to BCG. By microscopic examination of neutrophils phagocytizing FITC-labeled bacteria, it was shown that both M. leprae and BCG were slowly ingested but that more BCG appeared to be associated with the cell membrane of more of the cells. When phagocytic cells were incubated with BCG and M. leprae for 30 min and subsequently examined by electron microscopy, few organisms were seen in either neutrophils or monocytes. This suggests that BCG are easily recognized and slowly ingested by normal phagocytic cells, the majority of which respond with a strong oxidative burst. M. leprae appeared to only weakly stimulate phagocyte oxidative responses and were also slowly phagocytized.

Human phagocytic cell responses to Mycobacterium leprae and Mycobacterium bovis Bacillus Calmette-Guérin. An in vitro comparison of leprosy vaccine components

Components of current vaccines for Hansen's disease include Mycobacterium bovis Bacillus Calmette-Guérin (BCG) and killed Mycobacterium leprae. BCG infections in humans are rare and most often occur in immune-compromised individuals. M. leprae on the other hand, although not causing clinical disease in most exposed individuals, is capable of infecting and replicating within mononuclear phagocytes. Lymphocytes from patients with the lepromatous form of Hansen's disease exhibit defective lymphokine production when challenged in vitro with M. leprae. This may result in inefficient mononuclear phagocyte activation for oxidative killing. To study the ability of normal phagocytes to ingest and respond oxidatively to BCG and M. leprae, we measured phagocytic cell O2- release and fluorescent oxidative product formation and visually confirmed the ingestion of the organisms. BCG stimulated a vigorous O2- generation in neutrophils and monocytes and flow cytometric oxidative product generation by neutrophils occurred in the majority of cells. M. leprae, stimulated a weak but significant O2- release requiring a high concentration of organisms and long exposure. By flow cytometric analysis, most neutrophils were able to respond to both organisms with the generation of fluorescent oxidative products. Neutrophil oxidative responses to M. leprae were substantially less than responses seen from neutrophils exposed to BCG. By microscopic examination of neutrophils phagocytizing FITC-labeled bacteria, it was shown that both M. leprae and BCG were slowly ingested but that more BCG appeared to be associated with the cell membrane of more of the cells. When phagocytic cells were incubated with BCG and M. leprae for 30 min and subsequently examined by electron microscopy, few organisms were seen in either neutrophils or monocytes. This suggests that BCG are easily recognized and slowly ingested by normal phagocytic cells, the majority of which respond with a strong oxidative burst. M. leprae appeared to only weakly stimulate phagocyte oxidative responses and were also slowly phagocytized.

Rapid visualization of Acanthamoeba using fluorescein-conjugated lectins

We investigated the efficacy of fluorescein-conjugated lectins (FCLs) for the rapid visualization of Acanthamoeba species. Cultures of Acanthamoeba castellani, Acanthamoeba culbertsoni, and Acanthamoeba polyphaga were established on nonnutrient agar plates supplemented with Escherichia coli. Maximal trophozoite populations were established four to five days after initial subculturing; mature cysts were routinely noted three to six days later. At various time points, trophozoites and/or cysts were harvested and suspended in Page's saline. Following a previously described protocol, samples of the suspensions were placed on glass slides and incubated with one of a panel of 14 FCLs. At the end of the incubation period, the slides were examined using an epifluorescence microscope. Concanavalin A brightly stained both cysts and trophozoites. Wheat germ agglutinin brightly stained cysts but only minimally stained trophozoites. These results suggest that FCLs may be useful for rapid visualization of Acanthamoeba organisms in corneal infections.

Rhinitis, pneumonia, and defective neutrophil function in the Doberman pinscher

Eight closely related Doberman Pinschers with chronic rhinitis and pneumonia had normal or increased numbers of structurally normal leukocytes. Serum concentrations of immunoglobulins and complement were above or within normal ranges. Lymphocyte transformation indices for 3 mitogens were normal in 7 of the 8 dogs; the remaining dog had low values for all mitogens. Neutrophils phagocytized bacteria normally, but had impaired bactericidal ability. The bactericidal defect may have been related to the inability of neutrophils to generate normal numbers of oxygen radicals after stimulation, as determined by decreased ability of neutrophils to reduce nitroblue tetrazolium and to produce superoxide following opsonized zymosan stimulation. These observations, plus finding chronic inflammatory disease in the lungs of one dog, indicated that the disease may have some similarity to chronic granulomatous disease or to complement receptor deficiency in man.

Mycobacterium leprae fails to stimulate phagocytic cell superoxide anion generation

Mycobacterium leprae is an intracellular pathogen that is ingested by and proliferates within cells of the monocyte/macrophage series. Mechanisms by which intracellular pathogens resist destruction may involve failure to elicit a phagocyte "respiratory burst" or resistance to toxic oxygen derivatives and lysosomal enzymes. We have studied the ability of M. leprae and Mycobacterium bovis BCG to stimulate the generation of superoxide anion (O2-) in vitro by human blood neutrophils and monocytes and murine peritoneal macrophages. M. leprae bacteria failed to stimulate significant O2- release except at high bacteria-to-cell ratios (greater than 50:1) whether or not they were pretreated with normal serum or serum from patients with lepromatous leprosy. Either viable or irradiated BCG; on the other hand, stimulated the three cell types to release significant amounts of O2- when challenged with as few as 10 organisms per cell. Serum pretreatment enhanced the release of O2- by the three cell types. Preincubation for 18 h with viable M. leprae did not inhibit the ability of monocytes to respond with an oxidative burst to phagocytic stimuli. The failure of M. leprae to stimulate phagocyte O2- generation may be an important factor in its pathogenicity.

Isolation of canine neutrophil plasma membranes

This paper describes the isolation of plasma membrane vesicles formed by nitrogen cavitation of canine neutrophils. Plasma membranes from disrupted cells were separated from other membranes and organelles by Percoll-density gradient centrifugation. Transmission electron microscopic examination of membrane preparations chromatographed on either Sephacryl S-1000 or Sepharose 4B revealed that two populations of plasma membrane vesicles were formed: large (176 +/- 22nm), and small (119 +/- 11nm). Purified large vesicles were separated from Percoll and contaminating cytosol by Sephacryl S-1000 chromatography. Small vesicles were obtained free of Percoll by recavitating purified large vesicles. Problems encountered due to the presence of a soluble 5'-nucleotidase inhibitor also are discussed. Large and small membrane vesicles were separated into adherent and non-adherent populations by affinity chromatography on either concanavalin A-Sepharose or lentil lectin-Sepharose columns.

Mechanisms of lipopolysaccharide-induced protection against pseudomonas sepsis in granulocytopenic mice

The nature of the enhanced resistance to Pseudomonas aeruginosa sepsis induced by type-specific lipopolysaccharide vaccine was examined in a mouse model of cyclophosphamide-induced granulocytopenia. Mice actively immunized with type-specific vaccine survived significantly longer than did nonimmune mice (P less than .002) when challenged 8, 12, or 16 days after immunization. This protection was nonspecific eight days after immunization and specific 12 days after immunization. Passive immunization of mice with specific antibody resulted in significant, though minimal, protection. In contrast, long-term protection was observed when the passive transfer of specific antibody was combined with nonspecific immunization. This observation suggests that the specific protection observed with type-specific active immunization results from the interaction of specific antibody and an immunization-induced nonspecific cellular effector. While no significant effect of immunization on granulocyte counts in peripheral blood was demonstrated, studies of phagocytosis performed with peritoneal mononuclear cells suggest that the macrophage may be the immunization-induced, nonspecific cellular effector.

Characterization of canine neutrophil granules

The purpose of this study was to isolate distinct populations of canine neutrophil granules and to compare them with neutrophil granules from other species. Size, shape, density, and content of canine neutrophil granules were determined. Neutrophils obtained by Ficoll-Hypaque sedimentation were homogenized, and granule populations were separated by isopycnic centrifugation on a linear sucrose gradient (rho, 1.14 to 1.22 g/ml). The most dense granule population (rho, 1.197 g/ml) contained all of the myeloperoxidase, beta-glucuronidase, and elastase, more than half of the acid beta-glycerophosphatase, and most of the lysozyme. The population with intermediate density (rho, 1.179 g/ml) contained lactoferrin, vitamin B12-binding protein, and the remainder of the acid beta-glycerophosphatase and lysozyme. The least dense granule population did not contain a major peak of any of the enzymes or binding proteins tested but was distinguished by density and morphology. The size and shape of the granules were determined from scanning electron micrographs and assessment of shape was aided by transmission electron micrographs. By these methods three populations of canine neutrophil granules were characterized and named: myeloperoxidase granules, vitamin B12-binding protein granules, and low-density granules.

Nosocomial outbreak of nitrate-negative Serratia marcescens infections

Bacteremia due to multiply-antibiotic-resistant Serratia marcescens occurred within 1 week in four patients who were in adjacent beds in an intensive care unit. The strains were serotyped as O14:H12 and were nitrate negative. This unusual biochemical marker was useful in the investigation of the outbreak.

The effects of arachidonic and other fatty acids on canine neutrophil metabolism

The effect of arachidonic acid on the metabolic activity and chemiluminescence of canine neutrophils was investigated to gain further insight into its role in the neutrophil metabolic burst. Arachidonic acid was found to stimulate metabolic activity and luminol-augmented chemiluminescence. The increased metabolic activity was detected by both oxygen uptake measurements and assays of hexose monophosphate shunt activity. An inhibitor of lipoxygenase and cyclooxygenase, 5, 8, 11, 14-eicosatetraynoic acid prevented the hexose monophosphate shunt response to arachidonic acid. Aspirin or indomethacin, blockers of cyclooxygenase, inhibited chemiluminescence but failed to block the metabolic response to arachidonic acid. Since superoxide dismutase and 2-deoxyglucose, a blocker of glucose metabolism, inhibited the chemiluminescent response of neutrophils to arachidonic acid, it is likely that oxygen radicals produced via the hexose monophosphate shunt are required for the chemiluminescent reaction. In addition it was found that inhibition of cyclooxygenase activity blocked chemiluminescence but not the metabolic stimulation induced by sodium fluoride, suggesting that the chemiluminescence stimulated by sodium fluoride is associated with endogenous fatty acid stores. From these studies it can be concluded that arachidonic acid products of the cyclooxygenase pathway do not play a significant role in the metabolic response of neutrophils when arachidonic acid or sodium fluoride is the stimulant while the lipoxygenase pathway appears to be involved. The metabolic response is not linked to the chemical reaction that caused neutrophil chemiluminescence, although the chemiluminescent response depends on hexose monophosphate shunt activity and presumably the oxygen radicals that ultimately result from that process.

Stimulation of human and canine neutrophil metabolism by amphotericin B

The effect of an antifungal agent, amphotericin B, on human and canine neutrophil metabolism was studied. Commercial preparations of amphotericin B in concentrations ranging from 5 to 100 micrograms/ml stimulated neutrophil chemiluminescence in the presence of 10(-8) M luminol. This response was blocked by 2-deoxyglucose, a metabolic inhibitor, and by the absence of extracellular calcium ions. Neither pure amphotericin B nor the solubilizing agent present in the commercial preparation, alone or in combination, stimulated neutrophil chemiluminescence. Commercial amphotericin B caused an increase in oxygen uptake by neutrophils but no detectable superoxide anion production. Neutrophils were injured by commercial amphotericin B, as shown by an increase in trypan blue dye uptake but not cell lysis. Binding of amphotericin B to neutrophil membrane sterol with a subsequent alteration in membrane configuration is the most likely cause of metabolic stimulation.

Activation of human neutrophil metabolism by streptolysin O

The effect of streptolysin O on the metabolic activity of human neutrophils was examined. Streptolysin O, within the range of 3 to 75 hemolytic units, stimulated neutrophils to emit light. This chemiluminescence was the result of metabolic activation, as confirmed by oxygen uptake studies and the suppression of chemiluminescence by the metabolic inhibitor, 2-deoxyglucose. Free cholesterol, which prevents streptolysin O from binding to membrane cholesterol, blocked the neutrophil chemiluminescent response to streptolysin O. Extracellular calcium ions were necessary for the streptolysin O-stimulated chemiluminescent response of neutrophils. Some cell viability was lost, as measured by trypan blue uptake and neutrophil lysis within the range of streptolysin O concentration that caused metabolic stimulation. These observations suggest a possible role for streptolysin O as a pathogenic factor in streptococcal infections.