Systemic neutralization of interleukin-8 markedly reduces neutrophilic pleocytosis during experimental lipopolysaccharide-induced meningitis in rabbits.

Interleukin-8 (IL-8) is elevated in the cerebrospinal fluid (CSF) of patients with meningitis and is proposed to participate in subarachnoid-space pleocytosis. However, intracisternal injection of IL-8 into rabbits failed to induce indices typical of meningitis (leukocyte, tumor necrosis factor, or protein accumulation in the CSF or histopathological changes), indicating that merely increasing the CSF level of this chemokine is insufficient to induce inflammation in this anatomical site. IL-8 treatment did not affect inflammatory responses to subsequently intracisternally administered lipopolysaccharide (LPS). IL-8 was chemotactic for rabbit neutrophils in vitro, and subcutaneous injection of IL-8 (diluted in buffer or CSF) proved the in vivo activity of this peptide and suggested the absence of an IL-8 inhibitor in normal rabbit CSF. LPS-dependent pleocytosis was only slightly diminished by intracisternally administered murine anti-rabbit IL-8 monoclonal antibody (MAb) WS-4 but was dramatically reduced by intravenously administered MAb. Therefore, elevated CSF IL-8 levels may contribute to, but cannot solely account for, neutrophil influx into the subarachnoid space during meningitis. However, inhibition of IL-8 activity of the bloodstream side of the blood-brain barrier effectively reduces pleocytosis, indicating a central role of IL-8 in neutrophil influx into CSF during bacterial meningitis. Thus, inhibition of IL-8 is a possible therapeutic target for adjunct treatment of meningitis.

Neutrophil alpha-defensin human neutrophil peptide modulates cytokine production in human monocytes and adhesion molecule expression in endothelial cells.

Defensins, a family of small, cationic, antimicrobial peptides, are found in mammals, insects and plants. alpha-defensins are stored in granules of neutrophils and released upon activation by exocytosis. It was shown here that human neutrophil peptide (HNP), at concentrations of 10(-8) -10(-9) M, up-regulated the expression of TNF-alpha and IL-1 beta in monocytes activated with Staphylococcus aureus or PMA, while expression of IL-10 mRNA was down-regulated and production of IL-8 was not affected. HNP alone was unable to induce TNF-alpha or IL-1 beta expression in resting monocytes. At concentrations of 10(-4) -10(-5)M, HNP was cytotoxic for monocytes in serum-free medium. The cytotoxicity was abrogated in the presence of serum, while a cytokine-modulating effect of HNP was observed in the presence of serum and in whole blood, suggesting that this mechanism may function in vivo. Similarly, serum did not abrogate bactericidal activity of HNP. It was also demonstrated herein that HNP at 10 (-8) -10(-9) M, attenuated the inhibitory action of dexamethasone on TNF-alpha production. In parallel to monocyte studies, we have showed that HNP at concentrations ranging from 10(-9)M to 10(-6)M caused about 5-fold suppression of VCAM-1 expression in TNF-alpha-activated human umbilical vein endothelial cells, while the ICAM-1 expression was not affected. Our findings suggest that neutrophil defensins have the potential to modulate the inflammatory responses through regulation of cytokine production and adhesion molecule expression.

Expression of IL-8 gene in human monocytes and lymphocytes: differential regulation by TNF and IL-1.

TNF-alpha and IL-1 were reported to be the most powerful inducers of IL-8 in a multitude of cells, including leukocytes. In this study, we investigated TNF-alpha- and IL-1-mediated regulation of IL-8 gene expression in non-fractionated PBMC, and purified monocyte (MO) and lymphocyte (LY) fractions. Our analysis revealed that purified human MO did not respond to exogenous TNF-alpha with the induction of IL-8 mRNA or protein, nor require endogenous TNF-alpha for IL-8 expression. In contrast, in the presence of exogenous IL-1alpha and IL-1beta a substantial enhancement of IL-8 mRNA and protein expression in MO was observed. Nevertheless, antibodies to IL-1alpha and IL-1beta were unable to downregulate the expression of IL-8 in resting adherent or Staphylococcus aureus Cowan 1 (SAC)-stimulated MO. In contrast with MO, purified LY and non-fractionated PBMC expressed IL-8 in response to exogenous TNF-alpha, similar to exogenous IL-1alpha and IL-1beta. As was seen with MO, antibodies to TNF-alpha, IL-1alpha and IL-1beta did not inhibit the expression of IL-8 in purified LY and non-fractionated PBMC stimulated with SAC and LPS. Taken together, our data demonstrate major differences in responsiveness of MO and LY to exogenous TNF-alpha and IL-1, and suggest relative autonomy of IL-8 gene expression in these cells that does not require accessory cytokines but can be induced directly by exogenous stimuli.

Lassa and Mopeia virus replication in human monocytes/macrophages and in endothelial cells: different effects on IL-8 and TNF-alpha gene expression.

Cells of the mononuclear and endothelial lineages are targets for viruses which cause hemorrhagic fevers (HF) such as the filoviruses Marburg and Ebola, and the arenaviruses Lassa and Junin. A recent model of Marburg HF pathogenesis proposes that virus directly causes endothelial cell damage and macrophage release of TNF-alpha which increases the permeability of endothelial monolayers [Feldmann et al. , 1996]. We show that Lassa virus replicates in human monocytes/macrophages and endothelial cells without damaging them. Human endothelial cells (HUVEC) are highly susceptible to infection by both Lassa and Mopeia (a non-pathogenic Lassa-related arenavirus). Whereas monocytes must differentiate into macrophages before supporting even low level production of these viruses, the virus yields in the culture medium of infected HUVEC cells reach more than 7 log10 PFU/ml without cellular damage. In contrast to filovirus, Lassa virus replication in monocytes/macrophages fails to stimulate TNF-alpha gene expression and even down-regulates LPS-stimulated TNF-alpha mRNA synthesis. The expression of IL-8, a prototypic proinflammatory CXC chemokine, was also suppressed in Lassa virus infected monocytes/macrophages and HUVEC on both the protein and mRNA levels. This contrasts with Mopeia virus infection of HUVEC in which neither IL-8 mRNA nor protein are reduced. The cumulative down-regulation of TNF-alpha and IL-8 expression could explain the absence of inflammatory and effective immune responses in severe cases of Lassa HF.

Adenosine inhibits neutrophil degranulation in activated human whole blood: involvement of adenosine A2 and A3 receptors.

Adenosine, acting via A2 receptors, is a potent inhibitor of neutrophil oxidative burst, but its effects and mechanisms of action on neutrophil degranulation have been less well characterized. We, therefore, investigated the effects of adenosine and its receptor-specific analogues on neutrophil degranulation in stimulated human whole blood. Adenosine dose-dependently inhibited the LPS- and TNF-alpha-induced release of the azurophilic granule proteins bactericidal/permeability-increasing protein, elastase, and defensins to approximately the same extent, with a maximum inhibition of 70 to 80% and an IC50 ranging from 14 to 24 microM. The inhibitory effects of adenosine were partially blocked by the A2 receptor antagonist 3,7-dimethyl-1-propargylxanthine, the A1/A2 antagonist 8(p-sulfophenyl)theophyline, and the A1/A3 antagonist xanthine amine congener, but not by the A1 antagonist 1,3-dipropyl-8-cyclopentylxanthine. The highly selective A3 agonist N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide and the nonselective agonist 2-chloroadenosine reduced degranulation more potently than the A1 agonist N6-cyclopentyladenosine. The inhibitory effects of N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide and 2-chloroadenosine were strongly reversed by xanthine amine congener, but were not affected by 8(p-sulfophenyl)theophyline. In addition, the adenosine kinase inhibitor GP515 attenuated degranulation via an adenosine-mediated mechanism. These data indicate that adenosine acts via A2 as well as A3 receptors to inhibit neutrophil degranulation and add to the anti-inflammatory potential of adenosine and adenosine-regulating agents in neutrophil-mediated tissue injury.

[Effect of internal sequences in the Moloney murine leukemia virus genome on replication]. / Vliianie vnutrennikh posledovatel'nostei genoma virusa leikemii myshei moloni na replikatsiiu.

Construction and using of retrovirus vectors derived from the Moloney murine leukemia virus (MoMuLV) are described. These vectors, designated minimal vectors, contain the left and right long terminal repeats (LTRs), a binding site for proline tRNA, a polypurine tract (PPT), and a dominant marker for selective introduction of vectors into a packaging cell line, but lack the internal sequences of the virus genome. The experiments showed that the minimal vectors can be replicated and that their titer was approximately 1500-fold lower than that of wild-type vectors. The minimal vectors were shown to contain all the cis-acting sequences necessary for correct reverse transcription. One infectious virion. like wild-type viruses, produced only one provirus. Unlike the avian reticuloendotheliosis virus (REV), psi+ and psi(-)-genomes of MoMuLV did not compete for virion proteins in the psi2 packaging cell line. When an insert was introduced into a central part of the lTR U5 region, the titer of the minimal vector remained the same, while the titer of the wild-type vector decreased approximately 40-fold.

Homologous ELISA for detection of oligomeric human TNF: properties of the assay.

In order to quantify oligomeric human tumor necrosis factor-alpha (TNF), we have developed a sensitive homologous enzyme-linked immunosorbent assay (Hm-ELISA) using the same monoclonal antibody (MoAb) for both solid and liquid phase. Different anti-TNF MoAb have been compared in terms of their efficacy in the Hm-ELISA, affinity, neutralization capacity and epitope specificity. The data suggest, that effectiveness in the Hm-ELISA may represent a novel characteristic of MoAb. Of the MoAbs tested, 5 N was capable of recognizing oligomeric TNF in the Hm-ELISA with a detection limit of 15 pg/ml. Furthermore, using Hm-ELISA against human TNF, interleukin-8 (IL-8) and lymphotoxin, we have demonstrated that these cytokines are oligomeric in physiological solutions, but are converted into monomeric forms in the presence of the non-ionic detergent Tween 20. High salt buffer was employed to abrogate a nonspecific false positive reaction in the Hm-ELISA found in nearly half of the plasma samples obtained from healthy subjects. Finally, a good correlation between the Hm-ELISA and the L929 bioassay was observed for natural and recombinant TNF measured in human plasma.

[Transfer of dominant selective genes using retroviral vectors--a simple and quick method for obtaining hybridoma hybrids]. / Perenos dominantnykh selektivnykh genov pri pomoshchi retrovirusnykh vektorov--prostoi i bystryi metod polucheniia gibridov gibridom.

Two different techniques were used for labeling cells for subsequent generation of hybrid hybridomata. One of them was described earlier by De Lau and included isolation of an HATSNeoR double mutants of hybridomata cells. We proposed the second one consisting of introduction of dominant selectable genes conferring resistance to genecetin (G418) and hygromycin B into distinct hybridomata by retroviral vectors. Hybrid hybridomata secreting the bispecific antibodies have been obtained by both methods. However, comparison of the methods has revealed that highly efficient retroviral gene transfer of the selectable genes is a simpler and more convenient method for generation of cellular hybrids.

Differential action of cycloheximide and activation stimuli on transcription of tumor necrosis factor-alpha, IL-1 beta, IL-8, and P53 genes in human monocytes.

In the present study we have analyzed superinduction of TNF-alpha mRNA and enhancement of TNF-alpha gene transcription by cycloheximide (Chx) in human blood monocytes isolated by continuous Percoll gradient and activated in vitro. In the same monocyte cultures, we have compared the rate of gene transcription of TNF-alpha, IL-1 beta, IL-8, and the P53-antioncogene under the influence of plastic adherence, Staphylococcus aureus Cowan 1 (SAC), and Chx added at different times of monocyte culture. It was shown that the cytokine genes have low or negligible transcriptional activity in freshly isolated monocytes, whereas P53 gene transcription was constant in freshly isolated and in vitro-stimulated cells. Transcription of the IL-1 beta and IL-8 genes was induced by adherence and was not more enhanced by SAC. Transcription of the TNF-alpha gene was not induced by adherence. Chx added at the beginning of the monocyte culture did not block TNF-alpha or IL-1 beta gene transcription. IL-8 gene transcription, however, was abrogated by Chx. Addition of SAC to monocyte culture containing Chx caused significant enhancement of TNF-alpha gene transcription. Addition of Chx after 2.5 or 4 h of SAC activation caused "superinduction" of TNF-alpha mRNA and enhancement of TNF-alpha gene transcription. The data imply that TNF-alpha gene transcription in activated human monocytes might be regulated by both positive and negative regulatory factors that differ in their stability and protein synthesis dependence. In addition, results demonstrate that TNF-alpha, IL-1 beta, IL-8, and p53 genes in human monocytes are differently regulated.

[Differences in anti-oncogene p53 expression in human monocytes and lymphocytes in vitro]. / Razvitiia v ékspressii "antionkogena" p53 v monotsitakh i limfotsitakh cheloveka in vitro.

The p53 gene has been associated with malignant transformation as well as "anti-oncogene" activity. In the present report expression of p53 in resting and activated human blood monocytes and lymphocytes is analyzed. It is found that human monocytes freshly isolated by continuous percoll gradient centrifugation contained detectable level of p53 mRNA. Stimulation of monocytes by potent activation inducer Staphylococcus Aureus Cowan I for 3-5 hr caused disappearance of r53 mRNA. In contrast, induction of high level of TNF-alpha mRNA was detected. Addition of cycloheximide had no effect on p53 mRNA content in stimulated monocytes, and caused disappearance of mRNA in resting cells. In lymphocytes cultures p53 mRNA was absent in freshly isolated cells and in resting lymphocytes cultured for 20 hr. Activation of lymphocytes by lectin caused accumulation of p53 mRNA. We suggest that r53 gene regulation and functions might be different in human monocytes and lymphocytes.

[Effects of human defensin HNP-1 on the production of tumor necrosis factor-alpha by human blood monocytes in vitro]. / Vliianie defenzina HNP-1 neitrofilov cheloveka na produktsiiu faktora nekroza opukholei-al'fa monotsitami krovi cheloveka in vitro.

The influence of human defensin HNP-1 on the synthesis of tumor necrosis factor-alpha (TNF-alpha) by human blood monocytes was studied. It was shown that TNF-alpha production by human monocytes activated by SAC or PMA was augmented in the presence of HNP-1 concentrations of 10(-8)-10(-9) M. HNP-1 alone induced no synthesis of TNF-alpha. High concentration of HNP-1 (10(-4) M) was cytotoxic for human monocytes.

A sensitive enzyme-linked immunosorbent assay for human interleukin-8.

In order to quantify human interleukin-8 (IL-8), which is chemotactic for T cells and basophils as well as neutrophils, we developed an enzyme-linked immunosorbent assay (ELISA). Since binding inhibition tests indicated that three monoclonal antibodies (mAbs; BS-1, WS-4, WS-6) blocked the binding of 125I-labelled IL-8 to neutrophils, we tested an ELISA using these mAbs as primary antibodies, rabbit anti-IL-8 Ab as the secondary antibody, and alkaline phosphatase-labelled goat anti-rabbit Ab as the conjugate. Among the three mAbs tested, WS-4 was the most sensitive with a detection limit of 16 pg/ml. Several other cytokines, including monocyte chemotactic and activating factor (MCAF), which is structurally related to IL-8, showed no cross-reactivity in this system, indicating that this ELISA is specific for IL-8. The coefficients of variation for the intra- and interassays were below 10%. Furthermore, this ELISA also detected natural IL-8 (including both 72 and 77 amino acid forms) produced by cultured human cells and cell lines stimulated with IL-1, suggesting that this system will be useful in the detection of natural IL-8 in various body fluids.

The difference in p53 antioncogene transcription in human monocytes and lymphocytes.

The p53 gene is associated with malignant transformation as well as 'antioncogene' activity. In this report expression of p53 in resting and activated human blood monocytes and lymphocytes was studied. It is shown that human monocytes freshly isolated by continuous Percoll-gradient centrifugation contain detectable levels of p53 mRNA. Stimulation of monocytes by the potent activation inducer Staphylococcus aureus Cowan I (SAC) for 3-5 h caused the disappearance of p53 mRNA. In contrast, induction of a high level of tumor necrosis factor alpha mRNA was detected. The addition of cycloheximide did not increase the p53 mRNA content in stimulated monocytes, and decreased the mRNA level in resting cells. p53 mRNA was absent in freshly isolated lymphocytes and in resting cells cultured for 20 h. Activation of lymphocytes by phytohemagglutinin caused accumulation of p53 mRNA. We suggest that p53 gene regulation and functions might be different in human monocytes and lymphocytes.

[Synthesis of tumor necrosis factor-alpha (TNF-alpha) by human monocytes in vitro]. / Sintez faktora nekroza opukholei-alfa(FNO-alfa) monotsitami cheloveka in vitro.

The presence of TNF-alpha mRNA and protein in circulating human blood monocytes isolated by continuous Percoll gradient fractionation was studied. The technique of RNA isolation from the blood samples was used to study TNF-alpha mRNA expression. It was shown that human blood monocytes of healthy donors contained no presynthesized pool of TNF-alpha mRNA as well as no TNF-alpha protein.

An enzyme immunoassay for human defensins.

We developed and optimized an enzyme immunoassay for human neutrophil defensins, cationic cysteine-rich peptides that participate in host defense and inflammation. The assay utilizes a sandwich design with a monoclonal capture antibody and a biotinylated monoclonal detecting antibody. Cetrimonium bromide is employed to obviate non-specific binding of defensins to surfaces. The assay has a sensitivity of 0.04-0.05 ng/ml and a working range of 0.05-10 ng/ml.

[Localization of an antigenic determinant of recombinant interleukin-2, recognized by monoclonal antibody 13B1]. / Lokalizatsiia antigennoi determinanty rekombinantnogo interleikina-2, uznavaemoi monoklonal'nymi antitelami 13B1.

We suggest a simple approach to localization of antigenic determinants for the monoclonal antibody 13B1 raised against recombinant human interleukin-2. The approach is based on the limited trypsin proteolysis, peptide separation by the O'Farrell method and identification of the peptides, interacting with monoclonal antibodies, and comparison of the charge and length of these peptides with the corresponding values of theoretically possible peptides.

Tumor necrosis factor alpha induction in human monocytes.

The present study was undertaken to assess the presence of tumor necrosis factor (TNF)-alpha mRNA and protein in circulating human blood monocytes and to study the TNF-alpha gene expression in human monocytes isolated by continuous Percoll gradient fractionation. The technique of RNA isolation directly from the blood samples was used to study TNF-alpha mRNA expression in circulating human blood leukocytes. It was shown that human blood leukocytes of healthy donors contained no presynthesized pool of TNF-alpha mRNA as well as no TNF-alpha protein. It was found that early pretreatment with cycloheximide interferes with TNF-alpha mRNA induction by Staphylococcus aureus.

The use of syngeneic cells producing human somatotropic hormone (hSTH) for immunization of mice and development of hybridomas.

We studied the possibility of syngeneic cells expressing heterologous protein being used for sensitization of mice and production of hybridomas. Recombinant retroviral vector containing cloned human somatotropic hormone (hSTH) gene was used to express hSTH in BALB/3T3 cells. BALB/c mice were injected intrasplenically (i/s) or combination of intraperitoneally (i/p) and intrasplenically with hSTH-producing cells. Sensitized splenocytes were fused with myeloma cell P3X63-AgB.653. Screening for anti-hSTH hybridomas was performed by enzyme-linked immunoassay. Both single i/s injection of producer cells as well as combined i/s and i/p injections were effective for sensitization of splenocytes. Combined injection was effective for production of IgG and IgM secreting hybridomas. Single i/s injection led to generation of only IgM producing hybridomas. The results proved that syngeneic cells expressing genes of heterologous proteins can be used for splenocyte sensitization and hybridoma preparation.