bluuebunny/crossref_metadata_2025 huggingface dataset:
Differences in intracellular pool and receptor-dependent mobilization of the adhesion-promoting glycoprotein Mac-1 between eosinophils and neutrophils
Authors: Lundahl J , Halldén G , Hed J
Published: January 2018

Recruitment of cells to an inflammatory site is a process that is selectively regulated. At an inflammatory site caused by bacterial infection, predominantly neutrophil accumulation is observed. This is in contrast to air lergic inflammation, where predominantly eosinophil accumulation occurs. Mac-1 is an inducible adhesion molecule for both neutrophils and eosinophils. We examined the mobilization of this receptor on neutrophils and eosinophils after exposure to factors related to bacterial infections and allergic inflammation. We found more pronounced mobilization of Mac-1 on neutrophils than eosinophils after exposure to N-formylmethionyl- leucyl-phenylalanine, lipopolysaccharides, and activated sera (C5a). There was no significant difference in Mac-1 expression after exposure to aggregated immunoglobulin G. Incubation with interleukin-5 (IL-5) caused a significant increase of Mac-1 expression on eosinophils but not on neutrophils. Neutrophils seem to respond to a greater extent than eosinophils to factors related to bacterial infections, whereas eosinophils respond better to IL-5 associated with allergic inflammation. We measured the total pool of Mac-1 to evaluate whether these differences could depend on the size of the intracellular pool. Eosinophils had a larger total pool of Mac-1 than neutrophils. This finding increases the difference between eosinophils and neutrophils when relating the mobilized pool to the total pool. Stimulation with receptor- independent stimuli such as phorbol myristate acetate and ionomycin induced more pronounced mobilization of Mac-1 on eosinophils, but no differences were obtained if the mobilized pool was related to their total pool. These results indicate that the difference in responsiveness depends on different receptor-mediated signaling, since receptor-independent stimulation resulted in relatively similar mobilization of the intracellular pool of Mac-1. J. Leukoc. Biol. 53: 336–341; 1993.
C-reactive protein increases production of IL-1α, IL-1β, and TNF-α, and expression of mRNA by human alveolar macrophages
Authors: Rochemonteix Béatrice Galve-de , Wiktorowicz Krzysztof , Kushner Irving , Dayer Jean-Michel
Published: January 2018

The concentration of C-reactive protein (CRP) increases in human plasma up to a thousandfold during inflammatory states. Because tissue macrophages have been shown to have receptors for CRP, the question arises of whether these cells may respond to increased local concentrations of CRP by producing cytokines capable of participating in the inflammatory response. Accordingly, we examined the capacity of alveolar macrophages — relatively accessible human macrophages—to produce interleukin-1 (IL-1) and tumor necrosis factor a (TNF-α) in response to CRP. We found that production of IL-lα, IL-1β, and TNF-α, as measured by bioassay and immunoassay, increased in a dose-dependent manner after stimulation by CRP and that the levels of the respective mRNAs analyzed by Northern blot increased proportionally. These findings suggest that one of the fimctions of CRP may be to stimulate the production of IL-1 and TNF by macrophages at inflammatory sites where alterations of capillary permeability combined with an increased serum level lead to enhanced local concentrations of this acute-phase protein. J. Leukoc. Biol. 53: 439–445; 1993.
Analysis of the synergistic stimulation of mouse macrophage proliferation by macrophage colony-stimulating factor (CSF-1) and tumor necrosis factor a (TNF-α)
Authors: Guilbert Larry J , Winkler-Lowen Bonnie , Smith Anne , Branch Donald R , Garcia-Lloret Maria
Published: January 2018

Abstract: Tumor necrosis factor a (TNF-α) more than doubles tritiated thymidine ([3H]TdR) uptake in mouse macrophages stimulated by macrophage colony- stimulating factor (CSF-1). However, nothing is known of how TNF-α affects this increase or even whether it is manifested by increased cellular proliferation. Here we characterize the effects of TNF-α on CSF-l-stimulated proliferation of both primary cells (bone marrow-derived macrophages, BMMs) and a cloned growth factor-dependent macrophage cell line (SI). We show that the TNF- α-induced increase in [3H]TdR uptake of CSF-l-stimu- lated macrophages is directly proportional to an increase in the DNA content of the culture and that the effects of TNF-α are direct and independent of cell number. TNF-a decreases the population doubling time of log-phase growing macrophages having quite different growth rates to the same (approximately 30%) extent: the doubling time of BMMs decreases from 24 to 17 h and that of SI cells from 17 to 13 h. TNF-α exerts its effects on log-phase growth by increasing to the same proportion CSF-l-stimulated proliferation at all concentrations of CSF-1; that is, TNF-α does not shift, but rather amplifies, the CSF-1 dose-response curve. Although TNF-α alone does not stimulate macrophage proliferation, its presence in S1 cell cultures coming to quiescence after withdrawal of CSF-1 greatly increases subsequent CSF-l-stimulated [3H]TdR uptake as the cells reenter the cycle. Finally, we show that both human and mouse TNF-α increase CSF-l-stimulated log-phase growth and reentry of quiescent cells into the cycle equally on a molar basis (halfmaximal stimulation of approximately 0.3 nM). The latter observation argues that the growth-stimulatory effects of TNF-α are mediated via the 55-60-kd TNF receptor. We conclude that TNF-α acts directly on growth- competent macrophages to decrease significantly the population doubling time in a manner that enhances the mitogenic effects of CSF-1.
Countermeasures for ameliorating in-flight immune dysfunction
Authors: Fuchs Boris B , Medvedev Andrew E
Published: January 2018

We analyzed immune disturbances caused by the influence of spaceflight factors and proposed approaches for their correction. First, we determined the significant resistance of humoral immunity to the action of spaceflight factors, for example, B cell and immunoglobulin content, B cell reactivity to lipopolysac- charide, and distribution of B cell clones to trinitrophenyl (TNP group). A brief reversible increase of IgA and/or IgG concentration was the most characteristic shift observed. However, we noted prominent changes of T cells and natural killer (NK) cells, such as decreases in the content and phytohemagglutinin (PHA) reactivity of T lymphocytes, reduced T helper activity, and a reduction in NK cell cytotoxic activity in humans and animals during prolonged spaceflights. Rat bone marrow cells showed a decreased response to macrophage colony- stimulating factor. Studies with rat lymph node cells showed that microgravity and spaceflight stressors may influence lymphocytes in a tissue-specific manner. In experiments on isolated cells, human lymphocytes produced interferon more intensively in a reduced-gravity (microgravity) environment than under terrestrial conditions. However, lymphocyte activation by concanavalin A was sharply suppressed. Under microgravity conditions the transfer of activating signal to protein kinase C was strongly reduced. Thus, in-flight disturbances of T and NK cell functions are quite significant and could cause some diseases. However, to date the in-flight immune dysfunctions have not been excessive. Probably, we are mainly dealing with a complex of changes of immunity in space that is similar to that in the presence of acute stress. Therefore, it is reasonable to consider stress-related immunotherapy approaches in the practice of space medicine. The most effective methods and approaches of modern immunotherapy, such as artificial vaccines, monoclonal antibodies and immunoconjugates, recombinant cytokines, or immunomodulators etc, are also reviewed.
Dietary supplementation with n-3 fatty acids suppresses interleukin-2 production and mononuclear cell proliferation
Authors: Endres Stefan , Meydani Simin N , Ghorbani Reza , Schindler Ralf , Dinarello Charles A
Published: January 2018

We studied the in vitro production of interleukin-2 in nine healthy volunteers who added 18 g/day of fish-oil concentrate rich in n-3 polyunsaturated fatty acids to their normal Western diet for a period of 6 weeks. Interleukin-2 synthesis from stimulated peripheral blood mononuclear ceils was suppressed from 6.2 ng/ml at baseline to 2.2 ng/ml 10 weeks after the end of n-3 fatty acid supplementation (65% decrease; P - .04). At the same time phytohemagglutinin-induced proliferation of mononuclear cells was suppressed by 70% from the presupplement level. Interleukin-2 production returned to the premedication level at the end of the studies. The results suggest that the effect of dietary n-3 fatty acids in some diseases may be mediated in part by decreased production of interleukin-2 and decreased mononuclear cell proliferation.
Monocyte chemoattractant protein 1 (MCP-1) expression occurs in toxic rat liver injury and human liver disease
Authors: Czaja Mark J , Geerts Albert , Xu Jun , Schmiedeberg Phyllis , Ju Yue
Published: January 2018

Considerable evidence suggests that monocytes/macrophages play a crucial role in the process of liver injury and repair. Recent investigations have focused on the function of various macrophage-produced cytokines in liver disease. Much is still unknown, however, about the mechanism of macrophage recruitment and activation during liver disease. To further define this process, the gene expression of the monocyte chemoattractant monocyte chemoattractant protein 1 (MCP-1) was examined in animal and human liver disease. MCP-1 mRNA was not found in normal rat liver by Northern blot analysis. After single-dose treatments with the hepatotoxins carbon tetrachloride and galactosamine, MCP-1 mRNA was detectable beginning at 2 and 4 h after treatment, respectively, and was expressed continuously until 60–72 h. During chronic carbon tetrachloride administration, MCP-1 mRNA levels were elevated for the entire 10 weeks of treatment with peak levels of expression occurring early (weeks 1–3) and late (weeks 8–10) in this model. Isolated liver cell fractions from rats treated for 3 weeks with carbon tetrachloride revealed the major cellular source of MCP-1 mRNA to be fat-storing or Ito cells, with some expression occurring in the endothelial cell fraction. Studies of potential inducers of hepatic MCP-1 expression showed that lipopolysaccharide, tumor necrosis factor-α, and interleukin-lα and β treatments all led to MCP-1 expression. Finally, studies of human liver samples revealed MCP-1 gene expression in nondiseased liver and greatly increased levels in livers from patients with fulminant hepatic failure. These data implicate MCP-1 from fat-storing cells as a modulator of the process of liver injury and further support a role for MCP-1 in the pathogenesis of human disease. J. Leukoc. Biol. 55: 120–126; 1994.
Endocytosis of sulfatides by macrophages: relationship to the cellular uptake of phosphatidylserine
Authors: Greenspan Phillip , Gutman Robert L
Published: January 2018

These studies initially examined the effect of sulfatides on the endocytosis of phosphatidylserine (PS) liposomes in J774 macrophages employing liposomes composed entirely of PS and the nonexchangeable radiolabel [3H]cholesteryl hexadecyl ether. Bovine brain sulfatides significantly inhibited the uptake of PS liposomes by macrophages to a level of approximately 15% of control values. To examine whether macrophages were also capable of recognizing and internalizing sulfatides, sulfatide-containing liposomes were prepared using phosphatidylcholine (PC), cholesterol, and sulfatides (6:2:4 molar ratio) incorporating the same radiolabel. The sulfatide-containing liposomes were found to be avidly endocytosed by macrophages. Uptake of the sulfatide-containing liposomes by macrophages was significantly greater than the uptake of liposomes made without sulfatides. When the macrophages were incubated with the anionic compounds dextran sulfate and fucoidin, both the binding of the liposomes to the macrophages at 4° and the internalization of the liposomes at 37° were inhibited to approximately 10% of control values. The negatively charged phospholipids phosphatidylglycerol and cardiolipin significantly inhibited the uptake of sulfatide-containing liposomes, and PS was not effective in reducing the cellular uptake of these liposomes. Both oxidized low-density lipoprotein (LDL) and acetylated LDL reduced the uptake of the sulfatide-containing liposomes; the uptake observed in the presence of acetylated LDL and oxidized LDL was approximately 70% and 40%, respectively, of control values. These findings demonstrate that macrophages can efficiently endocytose both sulfatides and negatively charged phospholipids to remove them from the circulation. J. Leukoc. Biol. 55: 99–104; 1994.
Intracellular hydrogen peroxide and superoxide anion detection in endothelial cells
Authors: Carter Wayne O , Naryanan Padma Kumar , Robinson J Paul
Published: January 2018

One of the objectives of studying endothelial cells in vitro is to evaluate neutrophil-endothelial cell interactions including potential consequences of oxidant-mediated damage to the endothelial cell. Current under-standing of endothelial cell oxidative function is derived primarily from the measurement of extracellular products. We utilized 2 dyes, 2′,7′-dichlorofluorescin diacetate (DGFH-DA) and hydroethidine (HE), which measure hydrogen peroxide (H2O2) and superoxide anion (O2-) respectively, for their suitability to monitor oxidative mechanisms in endothelial cells and to provide a reliable measure of intracellular oxidants. Endothelial cells stained with DCFH-DA and stimulated with H2O2 exhibited an increase in the fluorescent product 2′,7′-dichlorofluorescein (DCF) (measure of intracellular H2O2) which peaked at 10 min. Endothelial cells stained with HE and stimulated with H2O2 exhibited an increase in the fluorescent product ethidium bromide (EB) (measure of intracellular O2-) which lasted for approximately 60 min. Superoxide dismutase increased DCF fluorescence in endothelial cells stimulated with H2O2 by 158%. Allopurinol (xanthine oxidase inhibitor) reduced DCF and EB fluorescence by 48% and 37% respectively in endothelial cells stimulated with H2O2. Catalase completely inhibited an increase in DCF or EB fluorescence in endothelial cells stimulated with H2O2. There was a direct correlation between mean DCF and EB fluorescence intensity and the concentration of H2O2 or the number of phorbol 12-myristate 13-acetate-activated neutrophils added to endothelial cells. We conclude from these studies that DCFH-DA and HE can be used to measure intracellular H2O2 and O2- in endothelial cells and that the xanthine oxidase pathway for intracellular O2- production accounts for approximately 40% of the total intracellular O2- generated in endothelial cells after stimulation with H2O2. The combination of image cytometry and flow cytometry will be important for future evaluations of endothelial cell function. J. Leukoc. Biol. 55: 253–258; 1994.
Identification and characterization of human neutrophil carbonic anhydrase
Authors: Campbell Andrew R , Andress Dennis L , Swenson Erik R
Published: January 2018

Many functions of polymorphonuclear leukocytes (PMNs) appear to alter and be affected by changes in the intracellular and/or extracellular acid-base milieu, suggesting that carbonic anhydrase (CA) may be important. Although small amounts of CA activity in PMNs have been reported, it has not been characterized fully. We therefore studied isolated mature circulating human PMNs and cultured HL-60 cells, an undifferentiated myelopoietic cell line, and compared these to human red cells (RBCs) for CA activity. Activity and sulfonamide inhibition were measured by a modified micromethod assay. Isoenzyme and total CA concentrations were determined by radioimmunoassay for human isozyme CA I, differential inhibition by MK-927, inhibition by 0.2% sodium dodecyl sulfate (SDS), and quantitative sulfonamide binding. Total CA activity (units/106 cells) was 0.04 in PMNs, 0.06 in HL-60 cells, and 0.62 in RBCs. Human PMNs have a total CA concentration of 1.3 μM, of which 0.9 μM is CA I and the remainder is CA II. Total loss of CA activity with 100 μM ethoxzolamide and 0.2% SDS ruled out significant CA III or CA IV activity. Subcellular fractionation of PMNs revealed that all CA activity was cytosolic. The absence of CA activity in mitochondrial and microsomal membrane fractions argues against any mitochondrial CA V or membrane-bound CA IV contribution to total CA activity. Neutrophils contain both CA I and II isozymes in roughly the same proportion as RBCs but at much lower concentrations, suggesting that in the course of maturation the CA content of neutrophils is regulated differently from that in erythrocytes. J. Leukoc. Biol. 55: 343–348; 1994.
The microcirculation and inflammation: modulation of leukocyte-endothelial cell adhesion
Authors: Granger D Neil , Kubes Paul
Published: January 2018

The accumulation of leukocytes in inflamed tissue results from adhesive interactions between leukocytes and endothelial cells within the microcirculation. These adhesive interactions and the excessive filtration of fluid and protein that accompanies an inflammatory response are largely confined to one region of the microvasculature: postcapillary venules. The nature and magnitude of the leukocyte–endothelial cell adhesive interactions that take place within postcapillary venules are determined by a variety of factors, including expression of adhesion molecules on leukocytes and/or endothelial cells, products of leukocyte (superoxide) and endothelial cell (nitric oxide) activation, and the physical forces generated by the movement of blood along the vessel wall. The contribution of different adhesion molecules to leukocyte rolling, adherence, and emigration in venules is discussed. Emerging views on potential endogenous antiadhesion molecules produced by endothelial cells as well as the influence of alterations in shear rate on leukocyte adhesion are addressed. Finally, the pathophysiological significance of the microvascular responses to inflammation are discussed in terms of adhesion-directed strategies for the treatment of different cardiovascular diseases and circulatory disorders. J. Leukoc. Biol. 55: 662–675; 1994.
The magnitude of HIV replication in monocytes and macrophages is influenced by environmental conditions, viral strain, and host cells
Authors: Chang Joon , Li Shan , Naif Hassan , Cunningham Anthony L
Published: January 2018

It has been difficult to standardize the effects of various stimuli on HIV replication in monocytes and macrophages in different laboratories. In this study we have shown that it is possible to standardize HIV inocula, culture conditions, and HIV antigen assay to achieve reproducibility with the same viral isolate and donor monocyte and macrophage. However, changes in serum concentration, in the strain of blood-derived isolate (even at low passage), in the donor source of the monocyte/macrophage, and in the state of cellular maturation all influenced HIV production by these cells. The donor source of monocytes contributed as much to variability in HIV production as the HIV strain and results were reproducible when the same source was used repeatedly. These in vitro data suggest that genetic differences may contribute to differences in HIV replication in macrophages and consequently to tissue virus load in vivo. J. Leukoc. Biol. 56: 230–235; 1994.
Molecular mechanisms of IL-4 effect on HIV expression in promonocytic cell lines and primary human monocytes
Authors: Naif Hassan , Ho-Shon Michael , Chang Joon , Cunningham Anthony L
Published: January 2018

HIV-1 can productively infect mononuclear phagocytes derived from blood, bone marrow, brain, and lung. Interleukin-4 (IL-4) and tumor necrosis factor-α (TNF-α) have previously been shown to stimulate HIV replication in monocytes and macrophages. The mechanism of IL-4 stimulation was investigated and compared with the known effects of TNF-α. IL-4 up-regulated the expression of HIV mRNA within the first 2 days after infection of promonocytic U-937 cells and 3 to 4 days after infection of plastic-adherent blood macrophages with HIV-1. TNF-α also up-regulated production of HIV RNA but to a greater degree than IL-4, reaching a peak 3–4 days after addition. Northern blot analyses showed an increase in genomic and spliced RNAs at these times. However, there was reduced stimulation of HIV mRNA production when IL-4 and TNF-α were combined. These techniques are being used to further elucidate the mechanism of action of cytokines that inhibit HIV replication in purified human monocytes and macrophages. J. Leukoc. Biol. 56: 335–339; 1994.
L-Selectin mediates downregulation of neutrophil TNF receptors
Authors: Richter Johan , Zetterberg Eva
Published: January 2018

Tumor necrosis factor (TNF) is a potent activator of neutrophil granulocytes, which acts via two cell-surface receptors: the p55-TNF receptor (TNF-R55) and the p75-TNF receptor (TNF-R75). Proteolytic cleavage of the extracellular region of the receptors results in formation of soluble TNF-binding proteins, TNF-R55-BP and TNF-R75-BP. We recently reported that adherence alone, without any further stimuli, causes release of both TNF-R55-BP and TNF-R75-BP and that both leukocyte-integrin-dependent and non-integrin-dependent adherence mechanisms can modulate TNF receptor expression. In the present work we show that crosslinking of a mAb to the adhesion protein l-selectin (TQ1) on the surface of neutrophils results in downregulation of TNF-receptor binding capacity. Furthermore, when the fluctuations of cytosolic free calcium found in adherent neutrophils were blocked with the cell-permeable calcium chelator BAPTA, adherence-induced release of TNF-R55-BP was inhibited. We have shown that adherence, via mechanisms involving two adhesion proteins, l-selectin and the CD11/CD18 leukocyte integrins, and fluctuations of cytosolic free calcium, can result in downregulation of neutrophil TNF-receptors. J. Leukoc. Biol. 56: 525–527; 1994.
Apoptosis in leukocytes
Authors: Squier Margaret K T , Sehnert Amy J , Cohen J John
Published: January 2018

All cells of the hematopoietic system have finite life spans, shorter by far than that of the host. They end their lives by committing a form of cellular suicide or programmed cell death. The morphology of this process is considerably different from that of necrosis and is called apoptosis. Apoptotic cells undergo a stereotyped sequence of changes, including shrinkage and nuclear collapse. The cell is quickly recognized and eaten by a phagocyte, without the elicitation of an inflammatory response. Although most cells have specific triggers of apoptosis, the killer T cell seems able to induce apoptosis in any cell it recognizes. The process of apoptosis is regulated by cytokines, and may be modulated both in vitro and in vivo. J. Leukoc. Biol. 57: 2–10; 1995.
Cyclic GMP and guanylate cyclase mediate lipopolysaccharide-induced Kupffer cell tumor necrosis factor-α synthesis
Authors: Harbrecht Brian G , Wang Stewart C , Simmons Richard L , Billiar Timothy R
Published: January 2018

Tumor necrosis factor-α (TNF-α) is an important mediator in sepsis and septic shock. Kupffer cells (KCs) are the resident macrophages of the liver and are potent producers of TNF-α in response to inflammatory stimuli such as bacterial endotoxin or lipopolysaccharide (LPS). Although the effects of exogenous cytokines such as interferon-γ on TNF-α production by macrophages have been fairly well studied, the intracellular pathways regulating KC TNF-α synthesis are largely unknown. We investigated the role of guanylate cyclase and cGMP in LPS-induced KC TNF-α synthesis. Exogenous 8-BrcGMP and dbcGMP increased LPS-stimulated TNF-α synthesis but had no effect on KC TNF-α in the absence of LPS. Sodium nitroprusside (SNP), a nitric oxide-releasing substance that stimulates guanylate cyclase, increased TNF-α synthesis in response to LPS, whereas methylene blue and LY83583, guanylate cyclase inhibitors, decreased KC TNF-α synthesis. The inhibitory effect of methylene blue could be overcome with exogenous dbcGMP or SNP. Our results demonstrate that guanylate cyclase and cGMP mediate LPS-induced KC TNF-α synthesis and suggest that agents that alter cyclic nucleotide metabolism in KCs may affect the response of these cells to inflammation and inflammatory stimuli. J. Leukoc. Biol. 57: 297–302; 1995.
Regulation of L-selectin and CD18 on bovine neutrophils by glucocorticoids: effects of cortisol and dexamethasone
Authors: Burton Jeanne L , Kehrli Marcus E , Kapil Sushila , Horst Ronald L
Published: January 2018

The responsiveness of bovine neutrophil L-selectin and CD18 to in vivo glucocorticoid administration was characterized by flow cytometric analysis. Blood was sampled intensively from dairy cows treated for 3 days with placebo, cortisol, or dexamethasone. Immunostaining was performed on whole blood (100 μ1) that was left unstimulated or was stimulated with platelet-activating factor (PAF; 1 μg/ml blood) prior to incubation with fluorescein isothiocyanate-conjugated monoclonal antibodies against L-selectin and CD18. Results were expressed as the percentage of positive-staining cells and as mean fluorescence intensity (MFI) of those cells. Total leukocyte count and leukocyte differentials were also performed on all blood samples. Dexamethasone caused nearly complete down-regulation of L-selectin (P < .01) on the surface of gated cells and reduced to half the MFI of CD18 (P < .01). Compared with values for the placebo group, dexamethasone began to cause L-selectin down-regulation within 8 h after the first injection and these effects persisted until 48 h after the third injection. This was correlated in time with an acute reduction in the proportion of cells that stained positive for L-selectin (from 98% before dexamethasone injections to a low of 17% by 40 h after the first injection). Dexamethasone also caused leukocytosis and neutrophilia during this time interval. In contrast, CD18 down-regulation was delayed until 16 h after the second dexamethasone injection and persisted for roughly 8 days. However, at no time during the experiment did dexamethasone influence the proportion of gated cells staining positive for CD18 (always 100%). Effects of cortisol were generally similar in pattern to those of dexamethasone but were more subtle and more readily detected when PAF was added to blood prior to immunostaining. These results strongly suggest that one mechanism of the anti-inflammatory action of glucocorticoids is to induce dramatic down-regulation of L-selectin and CD18 adhesion molecules on blood neutrophils. J. Leukoc. Biol. 57: 317–325; 1995.
Soluble and membrane-anchored forms of the human IFN-α/β receptor
Authors: Novick Daniela , Cohen Batya , Tal Natan , Rubinstein Menachem
Published: January 2018

The recently cloned ligand binding component of the type I human interferon-α/β receptor (IFN-α/βR) and its soluble analogue (p40) were characterized. p40 is a potent inhibitor of type I IFNs and antibodies directed against p40 completely block the activity of type I IFNs in human cells. These antibodies immunoprecipitate cellular 102-kDa (major) and 51-kDa (minor) forms of IFN-α/βR. We find that the 51-kDa IFN-α/βR is a disulfide-linked subunit of the 102-kDa IFN-α/βR. Two types of cDNA clones were isolated and sequenced, a 1.5-kb cDNA coding for the transmembrane 51-kDa IFN-α/βR and a 4.5-kb cDNA coding for p40. In addition to ligand binding, IFN-α/βR is directly involved in signaling, because it becomes phosphorylated at Tyr residues on ligand binding and it is physically associated with the cytoplasmic tyrosine kinase JAK1. J. Leukoc. Biol. 57: 712–718; 1995.
Interruption of cytokine networks by poxviruses: lessons from myxoma virus
Authors: McFadden Grant , Graham Kathryn , Ellison Kimberly , Barry Michele , Macen Joanne , Schreiber Martha , Mossman Karen , Nash Piers , Lalani Alshad , Everett Helen
Published: January 2018

Myxoma virus is an infectious poxvirus pathogen that induces a virulent systemic disease called myxomatosis in European rabbits. The disease is rapidly and uniformly fatal to susceptible rabbits and is characterized by generalized dysfunction of cellular immunity and multiple interruptions of the host cytokine network. A number of virus genes are classified as virulence factors because virus constructs bearing targeted gene disruptions induce attenuated disease symptoms. Many of these genes encode proteins that interact directly with effector elements of the host immune system. Included among these immunosubversive viral proteins are secreted mimics of host ligands or regulators (virokines) and homologues of cellular cytokine receptors (viroceptors). Five examples of these immune modulator proteins encoded by myxoma virus are reviewed: (1) myxoma growth factor, a member of the epidermal growth factor ligand superfamily; (2) SERP-1, a secreted serine proteinase inhibitor; (3) M11L, a receptor-like surface protein; (4) T2, a tumor necrosis factor receptor homologue; and (5) T7, an interferon-γ receptor homologue. The origin of viral strategies designed to subvert immune regulation by host cytokines is considered in the context of the biology of myxoma virus within immunocompetent hosts. J. Leukoc. Biol. 57: 731–738; 1995.
IL-15, a novel T cell growth factor that shares activities and receptor components with IL-2
Authors: Giri Judith G , Anderson Dirk M , Kumaki Satoru , Park Linda S , Grabstein Kenneth H , Cosman David
Published: January 2018

Interleukin 15 is a newly discovered cytokine that shares biological activities with IL-2 and, like IL-2, is a member of the four-helix bundle cytokine family. We have shown that IL-15 shares components of the receptor for IL-2: the α chain of the IL-2R is not required, but both the β and γ chains are needed for EL-15 mediated bioactivities. A defect in IL-15 signaling may therefore contribute to the phenotype of X-linked severe combined immunodeficiency in humans, resulting from mutations in the common γ chain. Differential ability of cells to bind and respond to IL-2 and IL-15 suggested the existence of an additional IL-15 specific receptor component. We identified an IL-15 specific binding protein (IL-15Rα) on a murine T cell and isolated the corresponding cDNA. The IL-15Rα is not a member of the hematopoietin receptor superfamily, but is structurally related to the α chain of the IL-2R. Differences in the expression pattern of EL-15 and its receptor compared to the EL-2 system suggest unique in vivo roles for IL-15. J. Leukoc. Biol. 57: 763–766; 1995.
CAP37, a neutrophil-derived multifunctional inflammatory mediator
Authors: Pereira H Anne
Published: January 2018

Cationic antimicrobial protein of M  r 37 kDa (CAP37) is a multifunctional protein isolated from the granules of human neutrophils, which has important implications in host defense and inflammation. CAP37 was initially recognized for its strong antibiotic activity against Gram-negative bacteria and was viewed as a component of the oxygen-independent killing mechanism of the neutrophil. However, we now know that CAP37 has more far reaching and important functions. It is a physiological protein released during inflammation with a high potential of regulating monocyte/macrophage functions, such as chemotaxis, increased survival, and differentiation. Recently, it has been demonstrated that CAP37 binds endotoxin. It has the structure of a serine esterase but lacks enzymatic activity. The bactericidal and endotoxin binding domains of the molecule have been delineated. The identification of functional peptides should provide new insight into the mechanisms of endotoxin binding, antimicrobial activity, and chemotaxis and in the long term provide key insights into therapies for treating infections and endotoxic shock. J. Leukoc. Biol. 57: 805–812; 1995.
Stem cell factor
Authors: McNiece Ian K , Briddell Robert A
Published: January 2018

Stem cell factor (SCF) is the ligand for the tyrosine kinase receptor okit, which is expressed on both primitive and mature hematopoietic progenitor cells. In vitro, SCF synergizes with other growth factors, such as granulocyte colony-stimulating factor (G–CSF), granulocyte macrophage–colony-stimulating factor, and interleukin-3 to stimulate the proliferation and differentiation of cells of the lymphoid, myeloid, erythroid, and megakaryocytic lineages. In vivo, SCF also synergizes with other growth factors and has been shown to enhance the mobilization of peripheral blood progenitor cells in combination with G–CSF. In phase I/II clinical studies administration of the combination of SCF and G-CSF resulted in a two- to threefold increase in cells that express the CD34 antigen compared with G–CSF alone. Other potential clinical uses include ex vivo expansion protocols and in vitro culture for gene therapy. J. Leukoc. Biol. 58: 14–22; 1995.
Monomeric bovine IgG2 is a potent stimulus for bovine neutrophils
Authors: Tao Weng , Corbett Martin J , Pickett Walter
Published: January 2018

Bovine plasma contains factors that can stimulate bovine neutrophils. Bovine plasma at 1:1,000,000–1:1,000 dilution induced a dose-dependent superoxide production in bovine neutrophils. When bovine plasma was fractionated with a protein G column, only the IgG fraction contained induction activity. At similar concentrations purified IgG induced a much stronger response than that of plasma IgG. Purified monomeric bovine IgG induced a dose-dependent increase in superoxide production. The maximum induction can be achieved at 100 μg/ml of bovine IgG. When subclasses of bovine IgG were examined, monomeric bovine IgG2 potently stimulated bovine polymorphonuclear leukocytes. In contrast, bovine IgG1 failed to induce a response at similar concentrations, and neither bovine IgG F(ab’)2 and Fc were effective. Both recombinant bovine granulocyte-macrophage colony-stimulating factor (r-BoGM-CSF) and recombinant bovine granulocyte colony-stimulating factor (r-BoG-CSF) primed bovine neutrophils for superoxide production induced by bovine IgG. The above results suggest that: (1) bovine plasma contain factors that can activate bovine neutrophils; (2) bovine plasma IgG is the major component that is responsible for bovine neutrophil activation; (3) bovine plasma contains factors that can inhibit the effect of bovine IgG; (4) monomeric bovine IgG2, but not IgG1, can activate bovine neutrophils directly without Fc receptor cross-linkage; (5) the integrity of bovine IgG is important in bovine polymorphonuclear leukocyte activation; and (6) bovine neutrophil activation induced by bovine IgG can be primed by r-BoGM-CSF or r-BoG-CSF. J. Leukoc. Biol. 58: 203–208; 1995.
Effect of PGE2 and of agents that raise cAMP levels on macrophage activation induced by IFN-γ and TNF-α
Authors: Mauël Jacques , Ransijn Adriana , Corradin Sally Betz , Buchmüller-Rouiller Yolande
Published: January 2018

The effect of prostaglandin (PG) E2 on macrophage activation by interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) was evaluated. Murine macrophages infected with Leishmania enriettii or Leishr mania major were activated by exposure to IFN-γ (10–50 U/ml) and TNF-α (30–3000 U/ml), leading to intracellular parasite destruction within 24–48 h. Leishmanicidal activity was markedly increased when activation was performed in the presence of PGE2 (10-9-10-7 M) or arachidonate (10-5 M, a PG precursor), concomitant with enhanced nitrite release and glucose oxidation through the hexose monophosphate shunt pathway. Conversely, activation was reduced by indomethacin and hydrocortisone, two inhibitors of PG synthesis. Parasite killing and nitrite production were fully restored by exogenous PGE2, indicating that inhibition by these drugs was related to their ability to block PG production. PG can stimulate adenylate cyclase, thus raising intracellular cAMP levels. Accordingly, dibutyryl-cAMP, theophylline (which prevents cAMP breakdown), and forskolin (an activator of adenylate cyclase) all stimulated macrophage activation. Finally, PGE2 and cAMP enhanced expression of inducible nitric oxide synthase mRNA in response to IFN-γ and TNF-α, and this effect was inhibited by the cAMP antagonist 2′-O-methyl adenosine. These findings are consistent with the hypothesis that PGE2 acts as a positive agonist in macrophage activation by IFN-γ and TNF-α via its capacity to modulate intracellular cAMP levels. .J Leukoc. Biol 58: 217–224; 1995.
Regulation of NK cells through the 80-kDa TNFR (CD120b)
Authors: Mason Anna T , McVicar Daniel W , Smith Craig A , Young Howard A , Ware Carl F , Ortaldo John R
Published: January 2018

By using monoclonal antibody specific for tumor necrosis factor receptor80 (TNFR80) (CD120b) and TNFRβo (CD 120a), we determined which receptor transduces the signals involved in activating natural killer (NK) cells. Purified CD56+CD3- large lymphocytes express TNFR80 but not TNFR60 and interleukin-2 (IL-2) up-regulates TNFR80 expression, consistent with NK cells being activated in vivo. Treatment of NK cells with anti-TNFR80 for 18 h enhanced the NK activity detected on K562 target cells mimicking the effect of TNF. In combination with IL-2, TNF enhanced the development of lymphokine-activated killing. However, only anti-TNFR80 abrogated IL-2 induction of lymphokine-activated killer cell activity. The activity of TNF or anti-TNFR80 was selective for NK cytotoxic function because they did not directly mimic IL-2 activation or induce significant proliferation, expression of cell surface activation antigens (CD25 or HLA-DR), or interferon-γ secretion. These results indicate that TNFR80 is an important signal transducing receptor for the differentiation of NK cells induced by TNF and IL-2. J. Leukoc. Biol. 58: 249–255; 1995.
A novel biological effect of platelet factor 4 (PF4): enhancement of LPS-induced tissue factor activity in monocytes
Authors: Engstad Charlotte Sissener , Lia Karin , Rekdal Øystein , Olsen Jan Ole , Østeoid Bjarne
Published: January 2018

In a previous study we have shown that granulocytes enhance lipopolysaccharide (LPS)-induced tissue factor (TF) activity in monocytes in a platelet-dependent reaction. The present investigation was undertaken to examine the role of a platelet activation product, platelet factor 4 (PF4), in LPS-induced TF activity in monocytes. Platelet lysate supernatant, purified PF4, and the COOH-terminal tridecapeptide of PF4, termed PF4(58–70), enhanced LPS-induced TF activity in monocytes of whole blood dose dependently. A monoclonal antibody against P-selectin eliminated the enhancing effect of PF4(58–70) on LPS-induced TF activity in monocytes, and PF4(58–70) was shown to act synergistically with tumor necrosis factor α (TNF-α). However, PF4(58–70) did not enhance TNF-α secretion in LPS-stimulated whole blood. The major effect of PF4(58–70) was granulocyte dependent. Our results suggest that PF4 might play an important role in LPS-stimulated monocyte TF activity of whole blood.
Stability of nuclear segments in human neutrophils and evidence against a role for microfilaments or microtubules in their genesis during differentiation of HL60 myelocytes
Authors: Campbell Michael S , Lovell Mark A , Gorbsky Gary J
Published: January 2018

The nucleus of the mature human neutrophil is segmented into three to five interconnected lobes. The physiological purpose of this segmentation is unknown, as is the mechanism by which the lobes are formed during differentiation. Using video observation of migrating human neutrophils simultaneously illuminated for fluorescence and phase-contrast microscopy, we analyzed nuclear movements with respect to cell shape changes. The number of nuclear lobes and their relative size remained constant during observation (up to 1 h). The thin connecting segments between the lobes elongated and attenuated extensively but never separated. Electron microscopic analysis of neutrophil nuclei revealed no specialized nuclear or cytoplasmic structures in the vicinity of connecting segments. With fluorescence in situ hybridization of whole chromosome probes, we determined that chromosomes are randomly distributed among neutrophil nuclear lobes. HL60 cells are a human myelocytic line that, with retinoic acid treatment, segment their nuclei and differentiate into neutrophil-like cells over several days. Using a rapidly responding variant line termed HL60/S4 (Cancer Res. 52, 949–954), we found that segmentation could be induced within 24 h. We tested the role of cytoskeletal elements in the process of nuclear segmentation. Neither the microtubule inhibitor nocodazole nor the microfilament inhibitor cytochalasin D prevented nuclear segmentation. Together, our studies suggest that nuclear lobes in neutrophils are relatively stable structures that are not generated by microtubule- or microfilament-dependent forces.
Cross-linking of CD18 primes human neutrophils for activation of the respiratory burst in response to specific stimuli: Implications for adhesion-dependent physiological responses in neutrophils
Authors: Liles W Conrad , Ledbetter Jeffrey A , Waltersdorph Ann W , Klebanoff Seymour J
Published: January 2018

Adhesion is known to prime neutrophils for physiological activation in response to cytokines and other stimuli. We have employed the technique of receptor cross-linking to study the potential role of CD18, the common β-subunit of the β2-integrin family of adhesion molecules, in the regulation of the respiratory burst, as measured by luminol-enhanced chemiluminescence and iodination, in human neutrophils. CD18 cross-linking primed neutrophils to activate the respiratory burst after stimulation with tumor necrosis factor α (TNF-α) (100 units/mL), formyl-methionyl-leucyl-phenylalanine (fMLP) (1 μM), and granulocyte-macrophage colony-stimulating factor (GM-CSF) (1 μg/mL), but not granulocyte colony-stimulating factor (G-CSF) (1 μg/mL), interferon-γ (IFN-γ) (100 U/mL), or phorbol myristate acetate (100 nM). The maximal rate of chemiluminescence induced by fMLP, TNF-α, and GM-CSF was enhanced 8-, 6-, and 1.5-fold, respectively, following CD18 cross-linking. Priming of the respiratory burst by direct engagement of CD18 was confirmed in neutrophil-mediated iodination experiments, where iodination induced by TNF-α, fMLP, and GM-CSF was increased 15-, 20-, and 7-fold, respectively, by CD18 cross-linking. Immunoblot experiments demonstrated that TNF-α-induced tyrosine phosphorylation was both accelerated and more intense in neutrophils after cross-linking of CD18. Major tyrosine phosphoprotein products include proteins with approximate molecular masses of 40, 70, and 110 kDa. Genistein (50μM), a selective tyrosine kinase inhibitor, reduced the TNF-α-stimulated respiratory burst by >80% whether or not CD18 was cross-linked. These results affirm the importance of CD18 in adhesion-dependent priming of neutrophil functions and demonstrate that CD18 engagement per se is sufficient to prime neutrophils for cytokine-induced signal transduction mediated by tyrosine phosphorylation.
Genetic approaches to study chemokine function
Authors: Lira Sergio A
Published: January 2018

Chemokines are cytokines capable of inducing Chemotaxis of inflammatory cells in vitro. It is likely that they are also involved in controlling cell migration in vivo, but this and other putative functions have not been properly validated to date. To investigate these functions in vivo, a number of new experimental approaches are required. This mini-review focuses on a set of genetic approaches that can be used to understand chemokine function at the level of the organism. Hopefully, these approaches will help us define the fundamental role of chemokines in development, homeostasis, and disease.
IL-1β primes IL-8-activated human neutrophils for elastase release, phospholipase D activity, and calcium flux
Authors: Brandolini Laura , Bertini Riccardo , Bizzarri Cinzia , Sergi Rita , Caselli Gianfranco , Zhou Dan , Locati Massimo , Sozzani Silvano
Published: January 2018

Interleukin-8 (IL-8), the prototype of the α (i.e., C-X-C branch) chemokine family, induced elastase release in a concentration-dependent manner (50-1000 ng/mL) in cytochalasin B-treated human polymorphonuclear leukocytes (PMNs). This response was potentiated about twofold if PMNs were preexposed to interleukin-1β (IL-1β) at concentrations that were by themselves inactive. The effect of IL-1β was clearly observed after 5 min and was maximal after a 30-min preincubation of the cells. The effect was present over the whole active concentration range of IL-8 and was completely blocked by the presence of IL-1 receptor antagonist. Priming of elastase release by IL-1β was not associated with a change in receptor number or affinity for IL-8. On the contrary, it was correlated with priming of phospholipase D activity and calcium flux activated by IL-8. Preincubation of the cells with ethanol and/or La3+ inhibited IL-8-induced degranulation, suggesting that activation of phospholipase D and increase of [Ca2+]i were important for this response. In contrast, ethanol and La3+ did not decrease the priming effect of IL-1β. IL-8 and IL-1β have been shown to be released by the same cell types and may be concomitantly present at sites of inflammation, giving rise to an amplification of the inflammatory response.
Control of the production of soluble interleukin-4 receptors: implications in immunoregulation
Authors: Femandez-Botran Rafael , Chilton Paula M , Ma Yuhe , Windsor Jana L , Street Nancy E
Published: January 2018

Soluble cytokine receptors (sCR) are generated in vivo through proteolytic cleavage of the membrane-bound receptors or by direct translation of mRNAs specifically encoding the soluble forms. Despite their widespread presence in biological fluids, the physiological role of endogenous sCR as immunoregulatory molecules is not yet well understood. In vivo, exogenous soluble interleukin-4 receptors (sIL-4R) have been shown to have both agonistic and antagonistic effects on IL-4 responses, depending on the relative concentration ratios of sIL-4R to IL-4. In an effort to elucidate the potential role of endogenous sIL-4R in the regulation of IL-4 responses, the mechanisms controlling the production of sIL-4R have been investigated. Although many cell types are able to constitutively produce low levels, production of sIL-4R is significantly up-regulated in vitro by T cell activation and IL-4. The ability of splenic cells to produce sIL-4R and the serum levels of sIL-4R have consistently been found to be increased during immune responses characterized by T cell activation and IL-4 secretion (Th2 responses). In agreement, clones of Th2, but not Th1, cells were found to significantly up-regulate sIL-4R production following antigenic stimulation. However, the production of sIL-4R by Th2 cells appears to be independent from that of IL-4 and can also be induced by cell contact and/or IL-1-dependent pathways. Taken together, these observations suggest that the production of sIL-4R in vivo is closely associated with the secretion of IL-4, and are consistent with the notion that endogenous sIL-4R are involved in the regulation of IL-4 activity during immune responses.