bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemokine expression in trinitrochlorobenzene-mediated contact hypersensitivity
Authors: Gautam Subhash , Battisto Jack , Major Jennifer A , Armstrong David , Stoler Mark , Hamilton Thomas A
Published: January 2018

The expression of the murine IP-10 and MCP-1 genes has been examined in the skin of mice during contact hypersensitivity reactions to the hapten trinitrochlorobenezene (TNCB). In both naive and passively sensitized animals, challenge with TNCB resulted in elevated expression of both genes as early as 4 h as detected by Northern hybridization analysis. Twenty-four hours after challenge, expression was markedly reduced in naive animals but remained elevated in sensitized animals. This prolonged expression of chemokine gene products correlates with the tissue swelling response generally used as a measure of delayed-type hypersensitivity (DTH) in this model and suggests that the continued expression of these genes results from the stimulation of hapten-specific T helper cells. Examination of cell type expression patterns by in situ hybridization using 3H-radiolabeled riboprobes confirmed the results of Northern hybridization experiments. Both genes were expressed predominantly in cells exhibiting the morphology of connective tissue fibroblasts, although the distribution of cells positive for IP-10 mRNA expression differed from that of cells expressing MCP-1 mRNA. IP-10 expression was localized almost exclusively to a population of connective tissue cells surrounding the fur follicle. MCP-1 expression was rarely found associated with fur follicles but instead was distributed throughout the dermis in cells embedded in the collagenous extracellular matrix. Surprisingly, neither endothelial cells lining the small vessels located deep within the dermis nor epidermal keratinocytes were positive under any of the conditions utilized in the present study. Expression of both IP-10 and MCP-1 has been previously reported in a variety of distinct cell types in vitro. The present results indicate that only a subset of the cell types with such potential are stimulated to express these chemokine genes in vivo during hapten-mediated DTH responses, implying the presence of subtle cell type- and tissue-specific control mechanisms. J. Leukoc. Biol. 55: 452–460; 1994.
Fluoride prevents degranulation of the azurophilic and specific granules in electropermeabilized neutrophils
Authors: Niessen Hans W M , Kessels G C Roger , Verhoeven Arthur J
Published: January 2018

The effect of A1F4- on the degranulation process in human neutrophils was investigated. In intact neutrophils, A1F4- induced degranulation, whereas in electropermeabilized neutrophils A1F4- did not stimulate degranulation. In electropermeabilized neutrophils, fluoride ions proved to be inhibitory for the degranulation induced by addition of Ca2+ and/or GTP-γ-S. Another phosphatase inhibitor, okadaic acid, inhibited degranulation induced by Ca2+ or by GTP-γ-S but not degranulation induced by the combination of Ca2+ plus GTP-γ-S. It is concluded that under suboptimal conditions of stimulation with Ca2+ or GTP-γ-S, protein dephosphorylation plays an important role in the degranulation response in human neutrophils. J. Leukoc. Biol. 55: 489–495; 1994.
HIV-1 associated down-modulation of CD4 gene expression is differentially restricted in lymphocytic and monocytic cell lines
Authors: Geleziunas R , Bour S , Wainberg M A
Published: January 2018

We previously demonstrated that chronic infection of a monocytic cell line (U-937) with human immunodeficiency virus type 1 (HIV-1) was not accompanied by down-modulation of CD4 transcription, unlike the situation with CD4+ T lymphocyte lines. To better understand the refractoriness of monocytes to alterations in levels of CD4 mRNA, we treated HIV-IIIB chronically infected U-937 cells with phorbol myristate acetate (PMA), a known stimulus of HIV gene expression. Although PMA caused a significant increase in HIV mRNA levels that was sustained over 7 days, no effect on CD4 transcript levels was noted. Clonal derivatives of HIV-IIIB infected U-937 cells, which produced a variety of infectious and defective particles, were likewise not affected in ability to produce CD4 mRNA. To rule out the possibility that U-937 cells select out HIV-1 variants unable to modulate CD4 mRNA levels, we passaged infectious virus from a U-937 clonal derivative (UHC1) onto different monocytic and T lymphocytic cell lines. In monocytic cell lines (U-937, PLB-985, THP-1), we observed an avirulent infection that did not affect CD4 mRNA levels, whereas UHC1 infection of each of two T lymphocytic cell lines (CEM-T4, Jurkat) caused both cytopathic replication and reductions in GD4 mRNA levels. In one case (Jurkat), variants expressing low CD4 mRNA may have emerged, because the outgrowth no longer expressed viral products. In the other case (CEM-T4), high expression of viral genes was accompanied by CD4 mRNA down-modulation, suggesting either that low-CD4-expressing variants were selected that maintained viral gene expression or that CD4 gene expression was repressed by viral products. J. Leukoc. Biol. 55: 589–595; 1994.
Class I and class II major histocompatibility molecules play a role in bone marrow–derived macrophage development
Authors: Armstrong Jason W , Simske Steven J , Beharka Alison A , Balch Signe , Luttges Marvin W , Chapes Stephen K
Published: January 2018

Class I and class II major histocompatibility complex (MHC) molecules play significant roles in T cell development and immune function. We show that MHCI- and MHCII-deficient mice have low numbers of macrophage precursors and circulating monocytes, as well as abnormal bone marrow cell colony-stimulating factor type 1 secretion and bone composition. We suggest that MHCI and MHCII molecules play a significant role in macrophage development J. Leukoc. Biol. 55: 658–661; 1994.
Human monocytes/macrophages: NO or no NO?
Authors: Denis Michel
Published: January 2018

The production of nitric oxide (NO) and other reactive nitrogen intermediates by cytokine-activated rodent cells is an important component of antimicrobial and/or antineoplasic activity of these cells. This pathway involves the oxidation of arginine to citrulline, with the concomitant release of NO by an inducible form of NO synthase (iNOS). Numerous cell types express iNOS after stimulation with bacterial products and/or cytokines. The role of NO and its derivatives in host resistance is a subject of intense investigation in mouse models of infections or neoplasia. Although human cells such as hepatocytes and endothelial cells have been shown to express an inducible NO synthase, the presence of such a pathway in human monocytes/macrophages has been questioned by many investigators and is a subject of great controversy. In this short review, we discuss some salient points of this debate. J. Leukoc. Biol. 55: 682–684; 1994.
The cooperative effects of TNF-α and IFN-γ are determining factors in the ability of IL-10 to protect mice from lethal endotoxemia
Authors: Smith Sidney R , Terminelli Carol , Kenworthy-Bott Lynne , Calzetta Angela , Donkin Jennifer
Published: January 2018

Recent studies have demonstrated that interleukin-10 (IL-10) has the capacity to protect mice from the lethal effects of endotoxin. In this investigation, we have examined the ability of IL-10 to protect both normal mice and Corynebacterium parvum-primed mice against endotoxin lethality. In the overwhelming majority of experiments, recombinant murine IL-10 (rMuIL-10) and recombinant human IL-10 (rHuIL-10) did not protect normal BALB/cJ mice from lipopolysaccharide (LPS)-induced lethality at doses up to 10 μg/mouse. Despite their inability to protect, both IL-10 preparations were highly effective in preventing the increase in serum tumor necrosis factor α (TNF-α) that occurred in response to the lethal dose of LPS. Moreover, a neutralizing antibody against TNF-α gave only partial protection when administered alone to BALB/cJ mice. Treatment with a combination of neutralizing antibodies against TNF-α and interferon-7 (IFN-γ) resulted in complete protection. In contrast to BALB/cJ mice, normal BDF1 mice were protected from lethal endotoxemia by treatment with both rMuIL-10 and rHuIL-10. However, IL-10 did not protect C. parvum-primed BDF1 against LPS lethality even though it caused a reduction in the LPS-induced serum TNF-α response in C. parvum-primed mice as well as in normal BDF1 mice. Neutralizing antibodies against TNF-α and IFN-γ were protective when administered alone to normal BDF1 mice, as previously demonstrated in C. parvum-primed mice. These findings suggest that lethal endotoxemia is a result of the cooperative activities of TNF-α and IFN-γ in normal mice of the BALB/cJ and BDF1 strains as well as in C. parvum-primed BDF1 mice. IL-10 appears to be less effective in protecting mice from lethal endotoxemia when cooperation between IFN-γ and TNF-α is facilitated by high-level production of the cytokines as in C. parvum–primed mice or when there is evidence of strong synergy between them as in normal BALB/cJ mice. J. Leukoc. Biol. 55: 711–718; 1994.
In vivo administration of a monoclonal antibody against the type I IL-1 receptor inhibits the ability of mice to eliminate Mycobacterium paratuberculosis
Authors: Kenefick K B , Adams J L , Steinberg H , Czuprynski C J
Published: January 2018

The purpose of this study was to determine the influence of endogenous interleukin-1 (IL-1) on resistance to paratuberculosis infection in experimentally infected gnotobiotic mice. Following a 6-month treatment with prednisolone to facilitate bacillary multiplication, control mice substantially reduced the numbers of M. paratuberculosis in the liver and ileum. In contrast, mice injected with a monoclonal antibody against the type I IL-1 receptor failed to reduce the numbers of M. paratuberculosis in the liver and ileum and exhibited more liver granulomas, which contained numerous acid-fast bacilli. These results indicate a significant role for endogenous IL-1 in host defense against experimental M. paratuberculosis infection in mice. J. Leukoc. Biol. 55: 719–722; 1994.
Relationship between phagosome acidification, phagosome-lysosome fusion, and mechanism of particle ingestion
Authors: Bouvier Gaelle , Benoliel Anne-Marie , Foa Colette , Bongrand Pierre
Published: January 2018

The fate of pathogens ingested by macrophages is dependent on phagosome acidification and fusion with different intracellular vesicles. Whereas the mode of particle recognition by the phagocyte seems the main determinant of phagosome-lysosome fusion, the influence of membrane reorganization, fusion events, and cell activation in phagosome acidification is not well known. We looked for a relationship between the nature of receptors involved in phagocytosis, phagosome acidification, and phagosome-lysosome fusion. Murine macrophage-like P388D1 cells were made to ingest sheep erythrocytes coated with immunoglobulin G (EIgG) or IgM and complement (ElgMC) or treated with glutaraldehyde and periodate (EGP). The following results were obtained: (1) As expected, the adhesion of the three particle types was differentially inhibited by monoclonal antibodies specific for FcγRII and GDllb/GD18. (2) The phagosomes containing all three particle types displayed similar acidification kinetics with a PH decrease to 6 within the first 10 min after ingestion. (3) Only phagosomes containing EIgG or ElgMG were fused with peroxidase-loaded secondary lysosomes. (4) Coating EGP with IgG only partially restored fusion, even when the surface density of IgG was markedly higher than found on EIgG. It is concluded that phagosome acidification and fusion are regulated by different mechanisms. Also, the lack of fusion observed with EGP is not entirely accounted for by the absence of stimulation of suitable receptors on the phagocyte membrane, because it cannot be restored by providing such a stimulus. J. Leukoc. Biol. 55: 729–734; 1994.
Role of the mevalonate pathway of isoprenoid synthesis in IL-8 generation by activated monocytic cells
Authors: Terkeltaub Robert , Solan Joell , Barry Michael , Santoro Denise , Bokoch Gary M
Published: January 2018

The highly regulated enzyme HMG-CoA reductase generates mevalonate, the precursor of a complex series of isoprenoids that posttranslationally modify (isoprenylate) certain proteins (e.g., the low-molecular-weight GTP-binding proteins) or that are incorporated into cholesterol and other end products. We recently reported that isoprenoids are required for NADPH oxidase activity in granulocytes via LMW GTP-binding protein isoprenylation. In this study, we evaluated the effects of isoprenoid depletion on the expression of proinflammatory genes in human monocytic THP-1 cells. We selected conditions under which pretreatment for 24 h with isoprenoid synthesis inhibitors (HMG-CoA reductase inhibitor lovastatin or compactin at 10 μM) did not compromise cell viability but markedly suppressed H2O2 generation. Under these conditions interleukin-8 (IL-8) production was attenuated (by 50–90%) in response to lipopolysaccharide, granulocyte-macrophage colonystimulating factor, and phorbol myristate acetate. Coincubation of reductase inhibitor-treated cells with mevalonate prevented the attenuation of IL-8 production by reductase inhibitors. The effects of isoprenoid depletion on cytokine production were selective: IL-1β generation was not inhibited but the production of IL-6 and IL-8 was concomitantly suppressed. IL-8 induction was suppressed at least in part through attenuation of the increase in mRNA in stimulated cells. We conclude that isoprenoid generation through the mevalonate pathway is a requirement for IL-8 induction by activated monocytic cells in vitro. Isoprenylation inhibitors have the potential to alter monocyte proinflammatory function. J. Leukoc. Biol. 55: 749–755; 1994.
Comparison of biological responses of human monocytes and THP-1 cells to chemokines of the intercrine-β family
Authors: Vaddi Krishna , Newton Robert C
Published: January 2018

The biological responses of human monocytes and cells of the monomyelocytic THP-1 cell line to stimulation with members of the β chemokine family are described in this report. All three chemokines tested, MCP-1, MIP-lα, and RANTES, elicited mobilization of intracellular free calcium in monocytes and THP-1 cells. The magnitude of response was highest with MCP-1 stimulation. MCP-1 desensitized monocyte responses to MIP-lα and RANTES, but no such desensitization was observed in THP-1 cells. MIP-lα or RANTES did not desensitize either monocytes or THP-1 cells to MCP-1 stimulation. All three chemokines elicited a potent chemotactic response in monocytes that was comparable in magnitude to that of f-Met-Leu-Phe. MIP-lα and RANTES required a fivefold higher dose than MCP-1 to elicit a peak response. On the contrary, THP-1 cells showed no significant chemotactic response. Studies of the desensitization of the monocyte chemotactic response indicated that all three chemokines are capable of causing complete homologous desensitization. Heterologous desensitization was observed only when monocytes were treated with MCP-1 followed by MIP-lα or RANTES. Studies of actin polymerization and cell polarization responses of monocytes indicated that these two responses attained peak magnitude after 10 min of stimulation with any of the chemokines. Dose-response kinetics were similar to those of the chemotactic response. THP-1 cells again failed to show either of these two responses. Finally, the activation potential of the chemokines was measured by their ability to induce respiratory burst. A tenfold higher concentration than that causing peak chemotactic response was required to elicit respiratory burst and no heterologous desensitization was noticed. Respiratory burst could be induced in THP-1 cells with a direct protein kinase C activator but not with any of the chemokines. These results indicate that, of the three examples tested, MCP-1 is the most potent member of the β chemokine family in the biological responses examined. Although a calcium response was elicited in THP-1 cells with chemokines, a lack of subsequent responses indicates some missing links in the downstream signal transduction pathways. J. Lcukoc. Biol. 55: 756–762; 1994.
Monomer-dimer equilibria of interleukin-8 and neutrophil-activating peptide 2. Evidence for IL-8 binding as a dimer and oligomer to IL-8 receptor B
Authors: Schnitzel Wolfgang , Monschein Ulrike , Besemer Jürgen
Published: January 2018

By chemical cross-linking experiments we show that at physiologically relevant concentrations IL-8 and NAP-2 monomers are in an equilibrium with dimers and even oligomers (Kd 300–800 nM). Oligomerization seems to be more prevalent for IL-8 than for NAP-2. The form in which IL-8 and NAP-2 bind to their specific receptors was analyzed in binding experiments with COS-1 cells expressing IL-8 receptor A or B in recombinant forms. Both receptors were cloned from the human myeloid leukemic cell line AML-193. Type A receptor had high affinity for IL-8 (K  d 4 nM) and low affinity for NAP-2 (K  d ≥700 nM), whereas the type B receptor was of equally high affinity (K  d 2 nM) for both IL-8 and NAP-2. However, IL-8 receptor B could bind specifically three to four times more IL-8 than NAP-2, and NAP-2 was a weak competitor for IL-8 binding to the same receptor. In addition, IL-8, but not NAP-2, could be cross-linked to dimers when bound to IL-8 receptor B. We suggest from these findings that IL-8, but not NAP-2, binds as a dimer and oligomer to IL-8 receptor B. J. Leukoc. Biol. 55: 763-770; 1994.
Role of Fcγ receptors in cancer and infectious disease
Authors: Wallace Paul K , Howell Alexandra L , Fanger Michael W
Published: January 2018

Receptors for the Fc domain of immunoglobulin G (FcγR) provide an interface between specific humoral immunity and the cellular branch of the immune system through their interaction with antibody. Gross-linking FcγR on myeloid cells triggers such diverse functions as clearance of immune complexes, phagocytosis of opsonized pathogens, secretion of reactive oxygen intermediates, and antibody-dependent cellular cytotoxicity. The FcγR play a major role in the removal of antibody-coated infectious agents and are the exclusive trigger molecules for tumor cell killing by human myeloid cells. Studies of FcγR function have been aided by the use of FcγR specific monoclonal antibodies, self-directed target cells, and bispecific antibodies that link target cells or pathogens to specific host cell molecules, including FcγR. These reagents have contributed significantly to our understanding of the role of the different classes of FcγR in mediating protection from various infectious agents and in mediating tumor cell killing. Taken together, these approaches have provided insight into the utility of manipulating Fc?R function in the therapy of cancer and infectious disease. J. Leukoc. Biol. 55: 816–826; 1994.
LPS-inducible nuclear factor in human monocytes that binds the negative regulatory element of the HIV LTR
Authors: Musso Tiziana , Bosco Maria Carla , Longo Dan L , Espinoza-Delgado Igor , Sica Antonio , Cox George W , Gusella G Luca , Forni Guido , Varesio Luigi
Published: January 2018

We studied the constitutive and lipopolysaccharide (LPS)-induced expression of nuclear protein binding to the negative regulatory element (NRE) of the human immunodeficiency virus type 1 (HIV-1) long terminal repeat (LTR) in fresh human monocytes. We demonstrated the existence of a constitutive factor binding to the NRE 73-bp HpaII/HpaII fragment (–216 to –143) whose expression is up-regulated by LPS treatment. Competition experiments with overlapping oligonucleotides covering the HpaII/HpaII fragment and with mutated oligonucleotides mapped the binding within the TTTCATCAC region (–171 to –163). This binding pattern is unique to human monocytes. J. Leukoc. Biol. 56: 21–26; 1994.
Urokinase-type plasminogen activator enhances invasion of human T cells (Jurkat) into a fibrin matrix
Authors: Kramer Michael D , Spring Herbert , Todd Robert F , Vettel Ulrike
Published: January 2018

The receptor for urokinase-type plasminogen activator (uPA-R) localizes uPA to the cell surface. The receptor-bound uPA converts plasminogen to the trypsinlike endopeptidase plasmin. Thus uPA is involved in the initiation of pericellular proteolysis. Pericellular proteolysis is assumed to facilitate the cellular infiltration into surrounding tissue. The uPA-R has recently been identified as a surface antigen of activated human T lymphocytes. We have characterized the uPA-R of the human CD4+ T cell line Jurkat by immunological (flow cytometry), biochemical (ligand blotting), and physico-chemical (Scatchard blotting) methods. The collective data suggest that the human CD4+ T cell line Jurkat expresses a cell surface receptor for uPA similar to that of myelo/monocytes and normal T cells with regard to size, affinity, ligand specificity, and antigenicity. Binding studies using exogenous uPA and subsequent functional assays revealed that receptor-bound uPA retains its enzymatic activity. Saturation of the Jurkat cell uPA-R with exogenous uPA facilitated cellular invasion into fibrin matrices in vitro. uPA-dependent invasion was inhibited in the presence of an anti-catalytic monoclonal anti-uPA antibody. We propose that uPA-R-bound uPA may facilitate the invasiveness of uPA-R-positive T lymphocytes. J. Leukoc. Biol. 56: 110–116; 1994.
Overview of HIV interactions with macrophages and dendritic cells: the other infection in AIDS
Authors: Crowe Suzanne M , Kornbluth Richard S
Published: January 2018

Since AIDS was first recognized as a unique clinical entity, a massive amount of effort has been devoted to the understanding and control of HIV infection. Several early reports indicated that HIV could infect cells of macrophage lineage, and, more recendy, the interactions between HIV and dendritic cells have become clearer. However, these cells have a special biology which has not always been taken into account by HIV researchers, although the virus itself has evolved special variants with the capacity to infect macrophages. Accordingly, the Second International Workshop on HIV and Cells of Macrophage Lineage was held in Sydney, Australia on December 6 and 7, 1993, in conjunction with the joint meeting of the Australasian Society for Immunology and the Society for Leukocyte Biology. The Organizers were Suzanne Crowe, Tony Cunningham, Richard Kornbluth, Monte Meltzer, and John Mills. Largely through the generosity of the Australian government, the Australian National Centre in HIV Virology Research, and the Society for Leukocyte Biology, this workshop brought together many of the investigators actively working in this field (although neither funds nor time allowed the complete meeting of all the investigators interested in this field). This special issue of the Journal of Leukocyte Biology originated with the ideas presented at this Workshop and provides a partial view of where this field has arrived. In addition, five papers on HIV-induced neuropathology have been included in a minisymposium put together independently of the Workshop by Howard Gendelman.
Macrophage-tropic HIV-1 variants: initiators of infection and AIDS pathogenesis?
Authors: Schuitemaker Hanneke
Published: January 2018

The importance of macrophage-tropic HIV-1 variants in AIDS pathogenesis becomes increasingly clear. Macrophage-tropic HIV-1 variants initiate infection, predominate in the asymptomatic phase, and persist throughout infection, even after the emergence of preferential T cell-tropic HIV-1 variants. HIV-1 infection of macrophages may contribute to the overall immune dysfunction observed in AIDS pathogenesis. Here, our knowledge of the biological variability of HIV-1, and specifically macrophage-tropic HIV-1 variants, is reviewed. Moreover, hypotheses about the mechanism of selection for macrophage-tropic variants in transmission, the mechanism by which these variants selectively persist in the asymptomatic phase, and how they may contribute to the general immune dysfunction are presented. J. Leukoc. Biol. 56: 218–224; 1994.
Significance of T cell apoptosis for macrophages in HIV infection
Authors: Kornbluth Richard S
Published: January 2018

Apoptosis is a major form of cell death in HIV infection. This review presents current ideas on the role of apoptosis in the development of AIDS. HIV may cause apoptosis either directly in individual CD4+ T cells through cellular infection and through the release of gp120 envelope protein, or indirectly by initiating systemic disturbances in the immune system. Furthermore, although apoptosis is often assumed to be a biological dead end, linear, unintegrated retroviral DNA survives apoptosis in avian leukosis virus systems. Macrophages avidly phagocytose apoptosing cells, and the viral DNA in apoptotic debris might spontaneously transfect macrophages and lead to the production of new virions. Such a hypothetical accessory infection pathway may explain why anti-HIV cytotoxic cells are unable to clear this virus from the body. Strategies directed against the “recycling” of the retroviral genomes present in apoptotic debris may ultimately have a role in the treatment of HIV infection. J. Leukoc. Biol. 56: 247–256; 1994.
HIV-1 entry and reverse transcription in macrophages
Authors: O’Brien William A
Published: January 2018

Although CD4 is required for efficient virus entry, it is not sufficient for entry of all primary HIV-1 strains. There may be additional virus-cell interactions, possibly involving the V3 region of the extracellular envelope protein, gp120, that occur following conformational changes induced by CD4 binding. This second interaction would precede fusion events and entry of the virus core. Primary HIV-1 strains appear to have a higher virion envelope density and retain gp120 better than HIV-1 strains adapted to growth in T cell lines in culture. These properties may confer a growth advantage in vivo to primary strains on the basis of less well exposed CD4 binding and neutralization domains. HIV-1 entry into both activated and quiescent T cells, as well as macrophages, is efficient for most primary strains, but there are different patterns of reverse transcription. Productive infection of activated T cells is associated with cell proliferation and accumulation of full-length reverse transcripts within 4 to 6 h. In resting, nondividing T cells, reverse transcription is aborted prior to full-length viral DNA formation. A third pattern of reverse transcription is seen in nondividing cultured macrophages with slow kinetics and accumulation of full-length viral DNA between 36 and 48 h. This rate can be increased by adding exogenous nucleotides, but still not to the rate seen in activated T cells. Future antiretroviral therapies may involve interference with cell-specific functions involved in reverse transcription. J. Leukoc. Biol. 56: 273–277; 1994.
HIV Infection of monocyte-derived macrophages in vitro reduces phagocytosis of Candida albicans
Authors: Crowe Suzanne M , Vardaxis Nicholas J , Kent Stephen J , Maerz Anne L , Hewish Marilyn J , McGrath Michael S , Mills John
Published: January 2018

HIV-1 infection of peripheral blood monocyte-derived macrophages (MDMs) is unrelated to the level of CD4 expression on the surface of the cell, is associated with considerable donor variability, causes minimal cytopathology, and results in peak viral antigen production after 2 weeks of infection. Phagocytosis of opsonized Candida albicans by MDMs infected in vitro with several strains of HIV was compared with that of uninfected cells from the same donors; the proportion of MDMs containing the fluorescein isothiocyanate—labeled yeast was determined by flow cytometry and phase contrast microscopy. The intracellular localization of C. albicans was confirmed by confocal microscopy. Using paired MDMs from nine donors, 81% of uninfected and 53% of HIV-infected MDMs phagocytosed C. albicans. In addition, the number of yeast per cell was significantly higher in uninfected MDMs than in HIV-infected cells (mean 6.1 versus 2.5). These findings may partially explain the high incidence of mucocutaneous candidiasis in HIV-infected patients with advanced disease. J. Leukoc. Biol. 56: 318–327; 1994.
Regulation of HIV expression by viral genes and cytokines
Authors: Vicenzi Elisa , Poli Guido
Published: January 2018

The human immunodeficiency virus (HIV) is the causative agent of the acquired immunodeficiency syndrome (AIDS), a leading cause of death among young individuals. As a complex pathogenic retrovirus, HIV is characterized in vitro and in vivo by the ability to establish either a latent or productive infection of CD4+ T lymphocytes and mononuclear phagocytes (MPs). Viral latency and expression are under the control of both viral genes and several host-related factors. Among these latter, several proinflammatory and immunoregulatory cytokines profoundly affect HIV replication in T lymphocytes and MPs in vitro. Because many of these cytokines have been found to be elevated in HIV-infected individuals, it is likely that they act as regulators of viral expression in vivo. Both viral genes and cytokines regulate transcriptional and posttranscriptional steps in HIV replication. Thus, it is likely that common regulatory pathways between these two distinct classes of regulator molecules will be identified in the near future and will provide potential targets for pharmacologic intervention and treatment of HIV disease. J. Leukoc. Biol. 56: 328–334; 1994.
Interferon-γ protects primary monocytes against infection with human immunodeficiency virus type 1
Authors: Fan Sharon X , Turpin Jim A , Aronovitz Jason R , Meltzer Monte S
Published: January 2018

Monocytes treated with 500 IU/ml human recombinant interferon-γ (rIFN-γ) 1 day before and continuously after human immunodeficiency virus (HIV) infection showed no evidence of virus replication 7 days after addition of the viral inoculum. There was no HIV- associated cytopathic effect, no reverse transcriptase (RT) activity or p24 detected in culture fluids, and no HIV RNA or DNA in cell lysates. Furthermore, no evidence of HIV infection was evident in replicate cultures in which all IFN-γ was removed at 7 days and the cells were cultured for an additional 3 weeks without IFN-γ. The 50% inhibitory dose for reduction of maximum RT activity in HIV-infected monocyte cultures was about 1 IU/ml IFN-γ. No increase in HIV replication was evident in monocytes treated with IFN-γ at any concentration (0 to 5000 IU/ml) or at any time (7 days before to 10 days after HIV infection). In side-by-side experiments with identical monocytes and HIV-1 stock, rIFN-γ was 10 to 20 times more effective than rIFN-α2b for induction of antiviral activity. With both interferons, significant antiviral activity was evident with monocytes treated 1 day before, at the time of, or up to 3 days after infection. At 7 to 10 days after infection (a time at which less than 20% of total cells were infected with HIV) addition of even high concentrations of IFN-α or IFN-γ had no effect on virus replication. These data suggest that the principal action of IFN-α and IFN-γ was directed against the fluid-phase virus. Cell-cell spread of infection within the HIV-infected monocyte culture and extent of virus replication in HIV-infected cells were not affected by interferon treatment. J. Leukoc. Biol. 56: 362–368; 1994.
Histochemical demonstration of hydrogen peroxide production by leukocytes in fixed-frozen tissue sections of inflammatory lesions
Authors: Dannenberg Arthur M , Schofield Brian H , Rao Jay B , Dinh Theresa T , Lee Ki , Boulay Marc , Abe Yasuharu , Tsuruta Junji , Steinbeck Marla J
Published: January 2018

The production of H2O2 by cells in cold paraformaldehyde-fixed frozen sections of inflammatory lesions was histochemically demonstrated by incubating them with diaminobenzidine (DAB) for 2 to 6 h. Catalase (150 μg/ml, about 1400 U/ml) inhibited the reaction, indicating that H2O2 was required to produce the chromogenic DAB product. Granulocytes (PMNs and eosinophils) were the main types of cells stained by the DAB reaction. Positive staining of macrophages was less frequent. The H2O2 was produced by metabolic enzymes that were still active after cell death and mild fixation. An atmosphere of 95 to 100% oxygen enhanced the specific DAB reaction, and an atmosphere of 100% nitrogen eliminated it. The DAB histochemical reaction to detect H2O2 requires the presence of peroxidases to produce the colored reaction product. Within our tissue sections, such peroxidases were evidently present in excess, because addition of low concentrations of H2O2 significantly increased the reaction product. Although some of the H2O2 produced by the granulocytes may have been derived from the dismutation of superoxide (O2-), the NADPH oxidase pathway for O2- formation did not seem to be involved: NADPH oxidase, a rather labile enzyme, should not be active after mild fixation, and diphenyleneiodonium (100 μM), an inhibitor of flavine-requiring NADPH oxidase, did not inhibit the reaction. Reactive nitrogen intermediates were also not involved, because NG-monomethyl-l-arginine and NG-nitro-l-arginine methyl ester, inhibitors of nitric oxide synthetase, did not appreciably inhibit the reaction. We conclude that stable, non-flavine-requiring oxidases, possibly cyclooxygenases or lipoxygenases, produced the H2O2 measured histochemically by our DAB reaction. These studies were made on tissue sections of acute dermal inflammatory lesions produced in rabbits by the topical application of 1% sulfur mustard [bis(2-chloroethyl) sulfide] in methylene chloride. Both intact PMNs and disintegrating PMNs in the base of the crust produced H2O2. Despite the production of H2O2 and the presence of peroxidase activity, no tissue damage was seen microscopically near the H2O2- producing cells, which indicates that the tissues are well protected by the antioxidants present in this self-limiting inflammatory reaction. J. Leukoc. Biol. 56: 436–443; 1994.
Essential involvement of interleukin-8 (IL-8) in acute inflammation
Authors: Harada Akihisa , Sekido Nobuaki , Akahoshi Tohru , Wada Takashi , Mukaida Naofumi , Matsushima Kouji
Published: January 2018

Neutrophil infiltration into inflammatory sites is one of the hallmarks of acute inflammation. Locally produced chemotactic factors are presumed to mediate the sequence of events leading to the infiltration at inflammatory sites. Interleukin-8 (IL-8), a novel leukocyte chemotactic activating cytokine (chemokine), is produced by various types of cells upon stimulation with inflammatory stimuli and exerts a variety of functions on leukocytes, particularly, neutrophils in vitro. However, no definitive evidence has been presented on its role in recruiting and activating neutrophils in the lesions of various types of inflammatory reactions. We administered a highly specific neutralizing antibody against IL-8 in several types of acute inflammatory reactions, including lipopolysaccharide (LPS)-induced dermatitis, LPS/IL-1-induced arthritis, lung reperfusion injury, and acute immune complex-type glomerulonephritis. Anti-IL-8 treatment prevented neutrophil-dependent tissue damage as well as neutrophil infiltration in these conditions. These results suggest that IL-8 plays a causative role in acute inflammation by recruiting and activating neutrophils. J. Leukoc. Biol. 56: 559–564; 1994.
Cross-linking of CD18 in human neutrophils induces an increase of intracellular free Ca2+, exocytosis of azurophilic granules, quantitative up-regulation of CD18, shedding of L-selectin, and actin polymerization
Authors: Walzog Barbara , Seifert Roland , Zakrzewicz Andreas , Gaehtgens Peter , Ley Klaus
Published: January 2018

Polymorphonuclear leukocytes (PMNs) exert most of their physiological functions while adherent to surfaces rather than in suspension. PMN adhesion is largely dependent on the function of the β  2 integrins, CDlla,b,c/CD18. We mimicked engagement of β  2 integrins by antibody cross-linking of CD18 on isolated human PMNs using both intact monoclonal antibody and F(ab’)2 fragments. Within seconds of CD18 cross-linking, we observed a significant, transient rise of intracellular free Ca2+ concentration by 200–300 nM, which was largely due to Ca2+ mobilization from intracellular stores. The Ca2+ signal was blocked after pretreatment with phorbol myristate acetate, an activator of protein kinase C, but not with herbimycin A, a potent inhibitor of tyrosine kinases. In addition to the rise of intracellular free Ca2+ concentration, CD18 cross-linking induced exocytosis of azurophilic granules (release of 26% of total PMN elastase), which was significantly inhibited by herbimycin A. Moreover, 2.2-fold up-regulation of CD18 antigen and significant down-regulation of surface expression of the granulocyte adhesion molecule L-selectin were induced. Granulocyte F-actin content as measured by nitrobenzoxadiazole-phallacidin increased significantly 1 min after CD18 cross-linking. By contrast, CD18 crosslinking by soluble antibodies did not induce superoxide production, but PMNs bound to immobilized monoclonal antibodies against CD18 released significant amounts of superoxide. Initial signaling through β  2 integrins does not appear to be mediated by a phospholipase C isoform activated through tyrosine phosphorylation, because the Ca2+ signal was not altered by herbimycin A. However, more complex cellular responses including exocytosis were found to require tyrosine phosphorylation. We show that engagement of β  2 integrins provides an important stimulatory signal to PMNs inducing degranulation, modulation of L-selectin, and cytoskeletal changes. J. Leukoc. Biol. 56: 625–635; 1994.
Antibody-facilitated macrophage killing of Trypanosoma musculi is an extracellular process as studied in several variations Of an in vitro analytical system
Authors: Albright Julia W , Stewart Michael J , Latham Patricia S , Albright Joseph F
Published: January 2018

Antibody-facilitated macrophage (MP) destruction of Trypanosoma musculi involves ingestion and intracellular degradation of the parasites. It is likely, however, as we show here, that death of the trypanosomes is extracellular and it is the corpses that are ingested by MPs. We have utilized both peritoneal MPs and a cloned line (WLG 5) of mouse MPs to analyze the killing of T. musculi. Both types of MP were more effective when activated by interferon-γ (IFN-γ) rather than lipopolysaccharide (LPS). When activated by both, LPS diminished the killing activity stimulated by IFN-γ, perhaps by changing the spectrum of lysins/toxins released by the MPs. Nitric oxide (NO) was found to be toxic for T. musculi and to be responsible, in part, for MP killing of the parasites. Although antibody and complement in concert caused lysis of T musculi, complement was not required for MP killing of the parasites. In the course of this investigation, we developed an in vitro system, involving line 5 MPs and plasma from infected mice containing resident parasites, that should prove satisfactory for detailed analyses of the mechanisms of the antibody-dependent, cell-mediated cure of T. musculi infection. J. Leukoc. Biol. 56: 636–643; 1994.
Neopterin production by HIV-1–infected mononuclear phagocytes
Authors: Dukes Carol S , Matthews Thomas J , Rivadeneira Emilia D , Weinberg J Brice
Published: January 2018

Neopterin is a pteridine produced by human mononuclear phagocytes, usually in response to interferon-γ (IFN-γ) stimulation. Increasing serum levels of neopterin correlate with clinical progression to AIDS in HIV-infected people, but the factors that contribute to these elevated levels are not established. We performed in vitro experiments to investigate the possibility that HIV-1 infection of mononuclear phagocytes directly induces enhanced neopterin production. We found that HIV-1-infected monocytes and peritoneal macrophages produced neopterin in quantities similar to amounts produced by uninfected cells. The HIV-infected cells responded to stimulation with IFN-γ as well as uninfected cells, with a 6- to 12-fold increase in neopterin production. We conclude that elevated serum levels of neopterin in HIV-infected individuals are not caused by HIV-1 infection of mononuclear phagocytes but may be a result of the normal response of mononuclear phagocytes to increased levels of IFN-γ. J. Leukoc. Biol. 56: 650–653; 1994.
Determinants of neutrophil HOCI generation: ligand-dependent responses and the role of surface adhesion
Authors: Chatham W Winn , Turkiewicz Anthony , Blackburn Warren D
Published: January 2018

Neutrophil (PMN) generation of HOCI, an oxidant important in mediating tissue injury by PMN proteases, requires PMN production of H2O2 and the catalytic activity of myeloperoxidase (MPO). Production of H2O2 and MPO release vary with the PMN activating ligand and are facilitated by cellular adhesion. Leukotriene B4, platelet-activating factor, heat-aggregated immunoglobulin G (HAIgG), tumor necrosis factor α (TNF-α), and f-Met-Leu-Phe (fMLP) all triggered significant superoxide production but negligible H2O2 or HOCI generation when added to suspended PMNs. Production of H2O2 was observed when fMLP, TNF-α, or HAIgG was added to PMNs adherent to bovine serum albumin (BSA)-coated wells, but significant production of HOCI was observed only when HAIgG was added to PMNs adherent to BSA-coated wells or when suspended PMNs treated with TNF-α were allowed to settle in BSA-coated wells. Even greater production of both H2O2 and HOCI was observed when PMNs were incubated in wells coated with IgG (SAIgG). HOCI generation, when observed, was accompanied by release of MPO. Nonadherent PMNs generated HOCI when treated with 50–100 ng/ml phorbol myristate acetate or when stimulated with fMLP following treatment with cytochalasin B; PMN activation under these conditions was also associated with MPO release but HOCI production was much less efficient relative to PMNs stimulated by SAIgG. These studies indicate that surface adhesion and ligand-induced responses that facilitate release of myeloperoxidase and dismutation of superoxide to H2O2 are required for production of extracellularly released HOCI; these responses are most efficiently utilized during PMN interaction with SAIgG. J. Leukoc. Biol. 56: 654–660; 1994.
Neutrophils, host defense, and inflammation: a double-edged sword
Authors: Smith John A
Published: January 2018

Neutrophils play important roles in host defense against all classes of infectious agents but, paradoxically, they are also involved in the pathology of various inflammatory conditions. Their microbicidal armory consists of oxidative and nonoxidative processes that are activated simultaneously upon phagocytosis. Although destruction of infectious agents occurs intracellularly, release of cytotoxic molecules into the extracellular milieu can damage body tissues. Neutrophils are heterogeneous. Subpopulations exist in various stages from dormant to primed to fully activated. The activities of neutrophils are regulated locally in microenvironments and systemically by a plethora of mediators including cytokines, “classical” neuroendocrine hormones, and bioactive lipids. The net response depends on a complex balance of stimulatory and inhibitory pathways that are regulated by these mediators. Although some effector and regulatory pathways are vital, considerable redundancy is also evident. Identification of the essential mediators and the unraveling of any interactions may be the keys to understanding the neutrophil paradox and developing therapeutic strategies that optimize microbial killing and minimize host tissue damage. Finally, reports that neutrophils can act as drug delivery vectors and that their function is influenced by stress and other lifestyle factors suggest that new homeostatic functions for these cells, outside their traditional roles in host defense and inflammation, remain to be identified: some are speculated on here. J. Leukoc. Biol. 56: 672–686; 1994.
Summary of the Fifth Conference on the Molecular Mechanisms and Physiological Activities of Cytokines
Authors: Oppenheim Joost J
Published: January 2018

The conference organizers, Drs. Joost J. Oppenheim, Benjamin Sredni, Jan Vaage, and David W. Weiss, were ably advised by a program committee consisting of a number of participants from the previous conference, many of whom participated in the present meeting.
Quantitative recovery of pulmonary intravascular macrophages from sheep lungs
Authors: Rogers Rick A , Tasat Debora R , Warner Angeline E , Brain Joseph D
Published: January 2018

Pulmonary intravascular macrophages (PIMs) adhere to the endothelium of lung capillaries and sequester circulating particles and pathogens from the blood. Iron oxide (γFe203) 5 mg/kg, administered intravenously, specifically labeled PIMs in situ within the living sheep. Attempts to isolate γFe203-labeled PIMs using vascular perfusion (VP) procedures yielded few cells. To improve recovery of PIMs, a proteolytic lung digestion (PLD) procedure was developed. Following PLD, γFe203-containing PIMs were recovered by magnets and the amount of γFe203 present measured by fluxgate magnetometry. Proteolytic lung digestion recovered 34% of the total γFe203 in lung samples and yielded 2 105 PIMs/g lung with 95% viability. In contrast, VP recovered only 3% of the total γFe203 in the lung; furthermore, less than 2% of the recovered γFe203 was cell associated. Proteolytic lung digestion followed by magnetic separation is an effective way to recover viable sheep PIMs for in vitro study. J. Leukoc. Biol. 56: 692–701; 1994.
Human neutrophils are selectively activated by independent ligation of the subunits of the CD11b/CD18 integrin
Authors: Petersen Meryl M , Steadman Robert , Williams John D
Published: January 2018

The yeast cell wall preparation zymosan is a particulate stimulus for human neutrophils (PMNs). Unopsonised zymosan particles bind to the PMN CD11b/CD18 integrin and are phagocytosed, leading to activation of the 5-lipoxygenase pathway and release of the lipid chemotaxin leukotriene B4 (LTB4). Specific monoclonal antibodies (mAbs) to CD11b and to CD18 were used in the present study to evaluate the contribution of each chain to these processes. All four anti-CD18 mAbs but none of five anti-CD11b mAbs dose-dependently blocked PMN phagocytosis of zymosan. Nevertheless, all anti-CD11b mAbs and all anti-CD18 mAbs significantly inhibited zymosan-stimulated LTB4 release in a dose-dependent manner. In addition, there was a dose-dependent stimulation of LTB4 release resulting from the specific ligation and cross-linking of either chain of the integrin heterodimer. Thus zymosan-stimulated LTB4 release is initiated by signals from both chains of the CD11b/CD18 integrin, whereas only CD18 is essential for phagocytosis. J. Leukoc. Biol. 56: 708–713; 1994.
Activation of arachidonic acid metabolism in mouse macrophages by bacterial amphiphiles
Authors: Card George L , Jasuja Rahul R , Gustafson Gary L
Published: January 2018

The relative activities of lipoteichoic acid (LTA) from four Gram-positive bacteria were compared to different lipopolysaccharide (LPS) preparations for activation of arachidonic acid metabolism in mouse peritoneal macrophages. Total eicosanoid was determined in cultures labeled with [3H]-arachidonic acid. Prostaglandin E2 (PGE2) and leukotriene C4 (LTC4) were determined by EIA analysis. The relative potencies of the different preparations were: smooth LPS from Salmonella abortus ≥ Re-LPS from Salmonella minnesota (R-595) ≥ LTA from Streptococcus pyogenes  Streptococcus faecalis  Staphylococcus aureus ≥ monophosphoryl lipid A derived from the Re-LPS > > LTA from Bacillus subtilis. Activation of eicosanoid release was inhibited by staurosporin for all of the amphiphiles tested. Treatment of the macrophage cultures with LTA from S. pyogenes, S. faecalis, and S. aureus, either in the presence or absence of indomethacin, desensitized the cells to eicosanoid release on subsequent challenge with LPS. The desensitized cells remained responsive to the phorbol ester phorbol myristate acetate. LPS from Gram-negative bacteria has immunostimulatory and endotoxic activities which result, in part, from the release of eicosanoids and other mediators from activated macrophages. The similarities in the patterns of cell activation by LPS and LTA suggest that lipoteichoic acids might contribute to the pathogenicities of Gram-positive bacteria. J. Leukoc. Biol. 56: 723–728; 1994.