Influenza A virus alters structural and biochemical functions of the neutrophil cytoskeleton

Influenza A virus (IAV) has previously been shown to alter chemotactic, oxidative, and secretory functions of polymorphonuclear leukocytes (PMNL). Because of the role of cytoskeletal proteins in these processes, studies were carried out to determine if IAV altered the PMNL cytoskeleton. PMNL were incubated with buffer of IAV, stimulated with f-met-leu-phe (FMLP), fixed and stained with NBD-phallacidin (NBD-Ph) and studied by flow cytometry. Mean F-actin fluorescence was increased 18% in virus treated cells pre-FMLP stimulation and 13% 5 and 10 min post-FMLP (P less than .03); no significant difference in F-actin fluorescence was noted in virus treated PMNL 15-30 s post-FMLP compared to control cells. PMNL exposed to the same conditions were solubilized and actin content was determined following SDS-PAGE of triton insoluble precipitates. Increased actin was recovered from virus treated compared to buffer treated cells before and after FMLP stimulation in the 8,000g precipitates (P less than .001). Immunofluorescent microscopy studies of F-actin distribution were done in PMNL stained with NBD-Ph following FMLP stimulation for 10 min. These studies showed an increased lamellipod F-actin/uropod F-actin ratio in PMNL pre-incubated with IAV compared to controls (4.6 vs. 1.0; P less than .025). Phosphorylation of specific cytoskeletal proteins was examined after immunoprecipitation. IAV alone altered phosphorylation of both vimentin and vinculin, and in stimulated PMNL virus led to decreased phosphorylation of vimentin and vinculin. These data show distributional and biochemical effects of IAV on PMNL cytoskeletal proteins, indicating additional targets for IAV interference in the PMNL signal-transduction-function process.

Depression of polymorphonuclear leukocyte functions by purified influenza virus hemagglutinin and sialic acid-binding lectins

Infection of polymorphonuclear leukocytes (PMNL) with influenza virus causes depression of PMNL metabolic and bactericidal activities. The studies reported here were undertaken to determine whether the hemagglutinin (HA) glycoprotein of influenza virus mediates this depression. PMNL were incubated with purified HA and the oxidative responses to exogenous stimuli were measured. The results indicate that HA, in either liposomes or protein aggregates referred to as rosettes, depressed PMNL oxidative responses. Depression was observed within 2 min of initial interaction of HA with PMNL and lasted more than 2 h. The membrane fusion activity of HA requires proteolytic cleavage of the HA, whereas the receptor binding activity does not. There was no difference in the ability of virions with cleaved or uncleaved HA to depress PMNL responses suggesting that the fusion event is not required for PMNL dysfunction. Inasmuch as the HA glycoprotein binds to sialic acid-containing receptors on the surface of the PMNL, we tested whether other sialic acid-specific binding proteins can mediate the reduction of PMNL responses. Sialic acid-specific lectins from Limulus polyphemus or Limax flavus were incubated with PMNL before measuring their responses to secondary stimulus. Depression was observed upon incubation with the lectins similar to that seen upon incubation with the HA or influenza virus. These results suggest that attachment of influenza virus to sialic acid-containing receptors is responsible at least in part, for suppressing PMNL oxidative responses.

Depression of polymorphonuclear leukocyte functions by purified influenza virus hemagglutinin and sialic acid-binding lectins

Infection of polymorphonuclear leukocytes (PMNL) with influenza virus causes depression of PMNL metabolic and bactericidal activities. The studies reported here were undertaken to determine whether the hemagglutinin (HA) glycoprotein of influenza virus mediates this depression. PMNL were incubated with purified HA and the oxidative responses to exogenous stimuli were measured. The results indicate that HA, in either liposomes or protein aggregates referred to as rosettes, depressed PMNL oxidative responses. Depression was observed within 2 min of initial interaction of HA with PMNL and lasted more than 2 h. The membrane fusion activity of HA requires proteolytic cleavage of the HA, whereas the receptor binding activity does not. There was no difference in the ability of virions with cleaved or uncleaved HA to depress PMNL responses suggesting that the fusion event is not required for PMNL dysfunction. Inasmuch as the HA glycoprotein binds to sialic acid-containing receptors on the surface of the PMNL, we tested whether other sialic acid-specific binding proteins can mediate the reduction of PMNL responses. Sialic acid-specific lectins from Limulus polyphemus or Limax flavus were incubated with PMNL before measuring their responses to secondary stimulus. Depression was observed upon incubation with the lectins similar to that seen upon incubation with the HA or influenza virus. These results suggest that attachment of influenza virus to sialic acid-containing receptors is responsible at least in part, for suppressing PMNL oxidative responses.

Meningitis due to Haemophilus influenzae type b resistant to ampicillin and chloramphenicol

Invasive disease due to Haemophilus influenzae type b (Hib) resistant to chloramphenicol and ampicillin is rare in the United States. Review of the literature reveals that all previously reported cases occurred in children with meningitis. These children were treated initially with ampicillin and chloramphenicol and had complicated courses characterized by delayed sterilization of the cerebrospinal fluid. The present report describes an infant who developed meningitis due to ampicillin- and chloramphenicol-resistant Hib. The patient received cefotaxime from the onset of therapy and had an uncomplicated course. The presence of Hib strains resistant to chloramphenicol and ampicillin should be considered in patients with meningitis due to Hib who respond poorly to treatment with these two drugs. Furthermore, the in vitro susceptibility of all Hib isolates to chloramphenicol (as well as to other antimicrobial agents) should be evaluated routinely. If the incidence of such resistant organisms increases, a change will be warranted in the commonly recommended combination of ampicillin and chloramphenicol as empiric therapy for bacterial meningitis in pediatric patients.

Synthesis of viral proteins in polymorphonuclear leukocytes infected with influenza A virus

Various reports have indicated that infection of polymorphonuclear leukocytes (PMNL) with influenza virus causes depression of their metabolic and chemotactic responses, but the effect the PMNL has on the life cycle of influenza virus has not been well defined. The studies reported here were undertaken to determine whether influenza virus could replicate within PMNL. Virus-infected and uninfected PMNL were labeled with [35S]methionine and analyzed by gel electrophoresis and fluorography for detection of newly synthesized proteins. Both host- and virus-specific proteins were produced within PMNL. By using indirect immunofluorescence techniques combined with flow cytometry, the expression of newly synthesized viral antigens was detected in virus-infected PMNL. Plaque assays on supernatant fluid from infected PMNL showed that infectious progeny were not produced, indicating that influenza virus infection of PMNL is abortive.

Alterations in cell protein phosphorylation in human neutrophils exposed to influenza A virus. A possible mechanism for depressed cellular end-stage functions

When polymorphonuclear leukocytes (PMN) are exposed to most harvests of influenza A virus (depressing virus, DV) for 20 min, chemotactic, secretory, and oxidative functions are depressed upon subsequent exposure to soluble or particulate stimuli. Other harvests of influenza A virus (non-DV) do not alter these activities. The DV-induced changes in multiple functions suggest the virus may interfere with steps involved in PMN activation. Because some of these steps may be regulated by protein phosphorylation, we examined the effect of non-DV and DV on cellular protein phosphorylation. PMN loaded with 32P-labeled inorganic orthophosphate were exposed to non-DV, DV, or buffer for 30 min; cells were then treated with buffer, FMLP (10(-6) M), or PMA (100 ng/ml) for 30 s. Samples were sonicated and centrifuged; cytosolic and particulate fractions were analyzed by SDS-PAGE and autoradiography. Exposure of PMN to either non-DV or DV caused phosphorylation of several cell proteins. However, when DV-treated PMN were then stimulated with FMLP or PMA, further phosphorylation was inhibited compared to non-DV- or buffer-treated cells. This suggests that DV-induced depression of PMN end-stage functions may be due to changes in cell protein phosphorylation. DV could interfere with phosphorylation of PMN proteins by altering protein kinase activity. We therefore examined the influence of non-DV and DV on some parameters that could affect kinase function. PMN intracellular [Ca2+] was monitored by using the fluorescent Ca2+ indicator, Indo 1, and cAMP levels were measured by RIA. PMN treated with DV alone or DV plus FMLP had higher intracellular [CA2+] than PMN similarly treated with non-DV or buffer. Exposure of PMN to non-DV, DV, or buffer caused minimal changes in cAMP levels, and similar increases occurred in cAMP levels upon FMLP stimulation. To determine whether DV interferes with transmembrane signaling, the effect of influenza virus on PMN transmembrane potential was studied by using a fluorescent cyanine dye. Transmembrane potential changes were greater in PMN exposed to DV than to non-DV or buffer; however, subsequent stimulation with FMLP caused equivalent changes in transmembrane potential. Our data show that protein phosphorylation in PMN is induced by DV and non-DV infection; upon subsequent stimulation with FMLP or PMA, there is inhibited cellular phosphorylation only in PMN previously exposed to DV.(ABSTRACT TRUNCATED AT 400 WORDS)

Alterations in cell protein phosphorylation in human neutrophils exposed to influenza A virus. A possible mechanism for depressed cellular end-stage functions

When polymorphonuclear leukocytes (PMN) are exposed to most harvests of influenza A virus (depressing virus, DV) for 20 min, chemotactic, secretory, and oxidative functions are depressed upon subsequent exposure to soluble or particulate stimuli. Other harvests of influenza A virus (non-DV) do not alter these activities. The DV-induced changes in multiple functions suggest the virus may interfere with steps involved in PMN activation. Because some of these steps may be regulated by protein phosphorylation, we examined the effect of non-DV and DV on cellular protein phosphorylation. PMN loaded with 32P-labeled inorganic orthophosphate were exposed to non-DV, DV, or buffer for 30 min; cells were then treated with buffer, FMLP (10(-6) M), or PMA (100 ng/ml) for 30 s. Samples were sonicated and centrifuged; cytosolic and particulate fractions were analyzed by SDS-PAGE and autoradiography. Exposure of PMN to either non-DV or DV caused phosphorylation of several cell proteins. However, when DV-treated PMN were then stimulated with FMLP or PMA, further phosphorylation was inhibited compared to non-DV- or buffer-treated cells. This suggests that DV-induced depression of PMN end-stage functions may be due to changes in cell protein phosphorylation. DV could interfere with phosphorylation of PMN proteins by altering protein kinase activity. We therefore examined the influence of non-DV and DV on some parameters that could affect kinase function. PMN intracellular [Ca2+] was monitored by using the fluorescent Ca2+ indicator, Indo 1, and cAMP levels were measured by RIA. PMN treated with DV alone or DV plus FMLP had higher intracellular [CA2+] than PMN similarly treated with non-DV or buffer. Exposure of PMN to non-DV, DV, or buffer caused minimal changes in cAMP levels, and similar increases occurred in cAMP levels upon FMLP stimulation. To determine whether DV interferes with transmembrane signaling, the effect of influenza virus on PMN transmembrane potential was studied by using a fluorescent cyanine dye. Transmembrane potential changes were greater in PMN exposed to DV than to non-DV or buffer; however, subsequent stimulation with FMLP caused equivalent changes in transmembrane potential. Our data show that protein phosphorylation in PMN is induced by DV and non-DV infection; upon subsequent stimulation with FMLP or PMA, there is inhibited cellular phosphorylation only in PMN previously exposed to DV.(ABSTRACT TRUNCATED AT 400 WORDS)

Depression of neutrophil function induced by viruses and its role in secondary microbial infections

A large body of evidence has accumulated indicating that viruses can predispose animal and human hosts to secondary local and systemic bacterial and fungal disease. The mechanism by which viruses cause these superinfections involves both a direct effect of viruses on the tissues at the site of infection and alterations in cells involved in immune surveillance. The effect of viruses on lymphocytes, monocytes, and macrophages has recently been reviewed. A number of viruses have been shown to depress various functions of polymorphonuclear leukocytes, which are critical for controlling bacterial and fungal infections. The alterations in functions of polymorphonuclear leukocytes induced by different viruses include abnormalities of adherence, chemotaxis, phagocytic, oxidative, secretory, and bactericidal activities. The effect of various viruses on neutrophils and the role that virus-induced neutrophil dysfunction has in predisposing the host to secondary infections are reviewed.

Buffy coat transfusions in neonates with sepsis and neutrophil storage pool depletion

A randomized study was initiated in neonates with neutropenia (absolute peripheral neutrophil count less than 1,500/microL) and suspected bacterial infection. Twenty infants with proven infection were enrolled, nine of whom had depletion of bone marrow stores of maturing neutrophils (less than or equal to 7% metamyelocyte, band and mature forms per 100 nucleated cells). These nine were randomized to receive 15 mL/kg of either buffy coat transfusions (group 2) or plasma and blood products (group 3). The remaining 11 (group 1) were observed. Peripheral neutrophil counts were monitored to determine the neutrophil response to transfusions. There were ten of 11 patients in group 1, two of four in group 2, and two of five in group 3 who lived at least seven days. No complications of transfusion were noted. No difference in the rate of peripheral neutrophil increase was found among the three groups. The study was stopped when it became clear that sufficient numbers of patients could not be entered into the study, in a reasonable period of time, to prove or disprove a clinically significant improvement in outcome. Although in vitro testing of the buffy coat preparations showed normal function in three of four cases, the clinical quality of the buffy coats may have been inadequate because of poor availability of whole fresh blood less than 24 hours old. The role of neutrophil transfusions in these patients remains unclear.

Granulocyte transfusion kinetics measured by chemiluminescence, nitroblue tetrazolium reduction, and recovery of indium-111-labeled granulocytes

A 20-year-old man with chronic granulomatous disease (CGD) and who was receiving granulocyte transfusions for a refractory liver abscess was studied to compare the kinetics of 111In-labeled granulocytes with those of two functional granulocyte assays, nitroblue tetrazolium reduction and chemiluminescence. Transfused granulocytes were eliminated in both rapid and slow phases. Peak recovery was noted in the first sample, which was obtained 10 minutes after transfusion for each assay. The elimination kinetics were similar over 24 hours. These results confirm the value of using 111In-labeled granulocytes as a marker of transfused granulocytes. These data also confirm that the oxidative metabolic function of granulocytes prepared by continuous-flow leukapheresis remains intact while in the recipient's circulation. The response of the patient adds support for the use of granulocyte transfusions in certain patients with CGD.

Suppression of endocytosis in neutrophils by influenza A virus in vitro

The effect of influenza A virus on the endocytic pathway in polymorphonuclear leukocytes (PMNLs) and the relationship of altered endocytic activity to virus-induced inhibition of other PMNL functions were examined with virus that caused decreased phagosomelysosome fusion and bacterial killing (depressing virus [DV]) and virus that did not (non-DV). Binding of both viruses to PMNL surface receptors was similar, but uptake of DV into PMNLs was decreased compared with that of non-DV. Both viruses were associated with the PMNL plasma membrane and were in endosomes. DV caused less stimulation of pinocytosis than did non-DV. The rate of exocytosis of fluoresceinated-dextran (FL-dextran) from cells stimulated with DV was significantly less than for non-DV. When PMNLs were pretreated with buffer, DV, or non-DV and then exposed to FL-dextran and N-formylmethionylleucylphenylalanine, the pinocytosis of FL-dextran was significantly less in cells pretreated with DV as compared with non-DV or buffer.

Cefuroxime versus ampicillin plus chloramphenicol in childhood bacterial meningitis: a multicenter randomized controlled trial

In a multicenter randomized trial, 107 children with bacterial meningitis were initially given either cefuroxime or ampicillin plus chloramphenicol. Patients were alternately assigned to 7- or 10-day courses of the designated antimicrobial regimen. CSF isolates included Haemophilus influenzae type b (89, of which 25% were beta-lactamase positive), Streptococcus pneumoniae, and Neisseria meningitidis. Although mean CSF bactericidal titers against Haemophilus isolates were 1:6 in each treatment group, H. influenzae was cultured from CSF in four of 39 patients receiving cefuroxime, 24 to 48 hours after initiation of therapy, compared with none of 40 patients given ampicillin plus chloramphenicol (P = 0.11). Clinical cure rates were similar (95%); one death occurred in each group. One child given cefuroxime had persistent meningitis after 5 days of therapy, and mastoiditis with secondary bacteremia developed in one on day 10. Three patients had relapse or reinfection. One patient who received cefuroxime for 10 days had a relapse of epiglottitis 17 days later, and of the patients given ampicillin plus chloramphenicol, one had a relapse of meningitis 1 week after 7 days of therapy, and bacteremia developed in one 42 days after completion of 10 days of therapy. No increase in either in-hospital complications or relapses occurred with a 7-day treatment course. Proof of the equivalence of the antibiotic regimens and the efficacy of 7-day courses of treatment, as well as the consequences of delayed CSF sterilization, will require additional investigation.

Self-injurious behavior in acquired sensory neuropathy

Self-abusive behavior, noted frequently in congenital sensory neuropathy, was observed in two children with acquired peripheral nerve dysfunction. In one case a laceration over the median nerve was followed by self-induced trauma to the fingers distal to the cut, while the other patient developed self-mutilation in all the extremities following insecticide poisoning and presented with signs of diffuse peripheral neuropathy. Improvement of the self-injurious behavior in each case seemed temporally related to the use of anticonvulsant medications, a treatment that is often suggested for older patients with paresthesias related to peripheral neuropathy. The apparent improvement in these two patients suggests that a trial of these drugs in additional patients with self-abusive behavior associated with peripheral neuropathy would be justified.

Neuraminidase activity is not the cause of influenza virus-induced neutrophil dysfunction

Influenza viruses have been shown to decrease the ability of polymorphonuclear leukocytes (PMN) to respond to a variety of stimuli. This study was done to determine if viral neuraminidase was responsible for decreased PMN function. Treatment of human PMN with purified neuraminidases from influenza virus, Vibrio cholerae, or Clostridium perfringens did not significantly affect the ability of human PMN to respond to stimulation. Occasional virus preparations that lacked the ability to depress PMN function did not differ in neuraminidase activity from viruses capable of causing depression. These results demonstrate that neuraminidase activity is not the cause of influenza virus-induced PMN dysfunction.

Intralipid infusion in neonates: effects on polymorphonuclear leukocyte function

In vivo and in vitro studies were done to assess the effects of Intralipid (IL) on neonatal polymorphonuclear leukocyte (PMNL) function. No significant abnormalities of chemotactic (CT) or chemiluminescent (CL) activities were noted in cord or adult PMNLs incubated with IL (10 mg/ml) when compared with paired controls incubated with buffer. In 14 premature and term neonates, IL was infused at 1 g/kg/24 h. Postinfusion CL activity of PMNLs was not significantly different from preinfusion CL activity. Although previous animal and human studies have shown abnormalities of PMNL function using higher infusion rates, slow infusion of IL at 1 g/kg/24 h produced no detectable alteration in PMNL oxidative function. The safety of long-term therapy with higher doses of IL remains to be proven.

The use of C-reactive protein from cerebrospinal fluid for differentiating meningitis from other central nervous system diseases

C-reactive protein (C-RP) determinations were performed by using the latex slide agglutination test on cerebrospinal fluid (CSF) from 235 patients. The patients were categorized into the following groups: bacterial meningitis (n = 74); viral meningitis (n = 10); fever without bacterial meningitis (n = 80); neurological symptoms without infection (n = 25); intracranial hemorrhage (n = 10); increased intracranial pressure that was secondary to pseudotumor cerebri or hydrocephalus (n = 16); and malignancies (n = 20). On the initial lumbar puncture, the C-RP was positive in 97% (72 of 74) of the patients in group 1, as compared with 0% (0 of 10), 6% (5 of 80), 20% (5 of 25), 50% (5 of 10), 6% (1 of 16), and 30% (6 of 20) in groups 2-7, respectively (P less than .0001). The C-RP test was able to detect bacterial meningitis with a sensitivity of 97% (72 of 74), a specificity of 86% (139 of 161), a positive predictive value of 77% (72 of 94), and a negative predictive value of 99% (139 of 141). These data indicate that C-RP determinations performed on CSF are useful and rapid clinical tests for the exclusion of the presence of bacterial meningitis in a patient.

Focal hepatic candidiasis: a distinct clinical variant of candidiasis in immunocompromised patients

Focal hepatic candidiasis is a distinct clinical variant of candidiasis in immunocompromised hosts. Although affected patients may exhibit previous evidence of extra-hepatic candidal infection, manifestations of disease at the time hepatic involvement is documented are localized to the liver. Five cases of focal hepatic candidiasis in immunocompromised patients were diagnosed antemortem in the past 15 months at our institution. Clinical, laboratory, and radiologic findings from those five patients, as well as from 20 additional cases reported in the medical literature, are reviewed. Patients with focal hepatic candidiasis had fever unresponsive to antimicrobial therapy, prominent gastrointestinal symptoms and signs, elevated levels of alkaline phosphatase, and hepatic, with or without accompanying splenic, defects noted on abdominal computed tomography. Liver biopsy usually revealed yeast and/or hyphal forms, but cultures were frequently negative. Response to therapy occurred in only 13 (59%) of 22 assessable patients. The apparent increasing incidence of focal hepatic candidiasis may be due to the recent use of more intensely cytotoxic chemotherapies for cancer.

Neutrophil storage pool depletion in septic, neutropenic neonates

A prospective study was done to determine the incidence of neutrophil storage pool (NSP) depletion in clinically septic neonates with peripheral neutropenia (less than 1500/mm3). Infants with NSP depletion were then randomized in a controlled study of polymorphonuclear leukocyte transfusions. Bone marrow examinations were done in 13 patients, and NSP depletion was noted in 3 (23%) patients. All patients with no NSP depletion had peripheral neutrophil recovery and 8 of 10 survived. Complications of meningitis contributed to both deaths. Two of the three patients with NSP depletion died. Neither the initial severity of illness nor the degree of peripheral neutropenia were predictive either of NSP depletion or of mortality. Most neonates with severe peripheral neutropenia and clinical sepsis had peripheral neutrophil recovery and survived with conservative management. Those at high risk could be identified only by examination of the NSP. Only those patients with NSP depletion should be considered for controlled studies of polymorphonuclear leukocyte transfusions.

Unreliability of radiographic diagnosis of septic hip in children

The radiographs of 19 pediatric patients with aspiration-proven bacterial infections of the hip were analyzed. The hip radiograph was abnormal in all neonates showing lateral subluxation. The radiograph was negative in eight of ten children more than 1 year of age. It is emphasized that children with suspected septic hip require immediate joint aspiration regardless of radiographic findings.

Characterization of the effect of influenza virus on polymorphonuclear leukocyte membrane responses

Depressed chemotactic activity of polymorphonuclear leukocytes (PMNL) infected with influenza virus could be due to changes occurring at the plasma membrane. The present study examined the effect of unopsonized influenza virus on chemotaxis, adherence, receptor binding, shape change, membrane fluidity, and release of specific granules from PMNL. Chemotactic activity of PMNL under-agarose to the chemoattractants, zymosan-activated serum ( ZAS ) and N-formyl-methionyl-leucyl-phenylalanine (fMLP), and adherence of PMNL to a plastic surface were markedly decreased in virus-treated cells as compared to control cells. The binding of fMLP to the PMNL was increased in virus-treated cells compared with control cells. Exposure of cells to virus, ZAS , or fMLP caused 35%-50% of the cells to become bipolar in shape, whereas less than 5% of the cells exposed to buffer became bipolar. Influenza virus did not alter membrane fluidity as measured by electron spin resonance spectroscopy with the probe 5-doxyl stearate. Virus-treated PMNL stimulated with FMLP or Staphylococcus aureus exhibited a marked decrease in the amount of lactoferrin released into phagosomes, onto the cells' outer membrane, and into the extracellular medium as compared to control cells. The possible relationship between inhibition of lysosomal enzyme degranulation and decreased chemotactic activity and adherence of PMNL is discussed.