bluuebunny/crossref_metadata_2025 huggingface dataset:
Entry of Human Immunodeficiency Virus-1 Into Glial Cells Proceeds via an Alternate, Efficient Pathway
Authors: Harouse Janet M , Laughlin Mark A , Pletcher Charles , Friedman Harvey M , Gonzalez-Scarano Francisco
Published: January 2018

Although the CD4 molecule is the cellular receptor for human immunodeficiency virus-1 (HIV-1) in cells of the lymphocyte/monocyte lineage, a number of investigators have also been able to infect cells, including several of central nervous system (CNS) origin, that do not express CD4 protein or mRNA. These infections are generally nonpermissive. To ascertain whether the nonpermissive nature of infection in glial cells is due to an inefficient entry pathway, we prepared a permanently transfected U373-MG cell line expressing the CD4 molecule and demonstrated that HIV-1 still replicates at a low level. Furthermore, a virus uptake assay indicated that HIV-1 enters glial cells effectively, even in the absence of CD4. These results demonstrate that HIV-1 entry is efficient and that the restrictive nature of the infection in glial cells is due to postentry mechanisms. In addition, these findings support the existence of an alternate, efficient, entry pathway in some glial cells.
L-Arginine-Dependent Production of a Reactive Nitrogen Intermediate by Macrophages of a Uricotelic Species
Authors: Sung Yen-Jen , Hotchkiss Joseph H , Austic Richard E , Dietert Rodney R
Published: January 2018

L-arginine-dependent production of reactive nitrogen intermediates (RNIs: nitric oxide, nitrite, and nitrate) by mammalian macrophages has been proposed to occur via an L-arginine oxidative deimination pathway and is known to be responsible for certain antineoplastic and antimicrobial effector functions. The present study represents the first examination of this pathway in a non-mammalian vertebrate. Because chickens, unlike mammals, lack a urea cycle and are incapable of de novo synthesis of L-arginine, the possible existence of an avian macrophage pathway for production of RNIs is questionable. We have defined conditions under which chicken macrophages are able to produce nitrite. Sephadex-elicited chicken peritoneal macrophages required a bacterial Ii-popolysaccharide (LPS from Escherichia coli) signal to produce nitrite during 24 hour cultures in the presence of L-arginine. As little as 5 ng/ml LPS resulted in significant nitrite production in culture. The relationship of nitrite production to both LPS and L-arginine levels was dose-dependent. D-arginine was unable to substitute for L-arginine but also produced no inhibitory effect In contrast, L-NG-monomethyl arginine showed a significant inhibitory effect on nitrite production. A virus-transformed chicken macrophage cell line, HD11, also produced nitrite in a dose-dependent manner relative to both LPS and L-arginine concentration. Concentrations as low as 5 ng/ml LPS and 0.1 mM L-arginine resulted in significant nitrite production, while maximum levels of nitrite production were obtained using ≥0.5 μg/ml LPS and ≥0.4 mM L-arginine. These results indicate that chicken macrophages can produce RNIs. This production is dependent upon activation and is influenced by local L-arginine concentration. Moreover, because the chicken does not possess the ability to synthesize arginine and has an absolute nutritional requirement for this amino acid, the chicken represents a highly controllable system to examine the in vivo effects of L-arginine on macrophage-related immune functions.
Inhibition of Stimulant-Induced Activation of Phagocytic Cells With Tetrandrine
Authors: Castranova Vincent , Kang Ji-Hee , Moore Mark D , Pailes William H , Frazer David G , Schwegler-Berry Diane
Published: January 2018

Tetrandrine is an alkaloid obtained from the root of a medicinal herb which is employed in China as a treatment for silicosis. One proposed mechanism for the development of silica-induced fibrosis is lung damage resulting from particle-induced inflammation and secretion of reactive compounds from alveolar phagocytes. Therefore, the objective of the present study was to determine if tetrandrine exhibited the ability to inhibit respiratory burst activity of pulmonary phagocytes. The data indicate that although tetrandrine is not cytotoxic to phagocytic cells, it is a potent inhibitor in vitro of zymosan-stimulated oxygen consumption, superoxide anion release, and hydrogen peroxide secretion by alveolar macrophages. Tetrandrine is also effective in vivo in preventing activation of alveolar macrophages after inhalation or intratracheal instillation of silica. Tetrandrine also inhibits stimulant-induced chemiluminescence by polymorphonuclear leukocytes. Since tetrandrine does not alter stimulant-induced depolarization of phagocytic cells, its inhibitory action is not via interference with receptor-ligand binding but rather must occur elsewhere in the stimulus-secretion coupling scheme.
Kinetics of the Biosynthesis of Complement Subcomponent C1q by Murine Macrophages: LPS, Immune Complexes, and Zymosan Alone and in Combination With Interferon-γ
Authors: Zhou Anqiang , Herriott Mary J , Leu Richard W
Published: January 2018

We investigated the effects of bacterial lipopolysaccharide (LPS), immune complexes (IC), and C3b opsonized zymosan (AZ) alone and in combination with lnterferon-γ (IFN-γ) priming on macrophage synthesis and secretion of C1q. Our results indicated that LPS, IC, and AZ alone stimulated C1q mRNA and secretion in the absence of IFN-γ. The increase in mRNA accumulation was detectable after 3 h, peaked at 6h and was maintained at constitutive levels for 24 h. There was a corresponding early burst of increased secretion of functional C1q after 3 to 6 h which declined rapidly after 9 to 24 h culture of LPS-stimulated macrophages. Priming of macrophages with IFN-γ and simultaneous triggering with LPS, IC, or AZ produced additive rather than synergistic increases in C1q mRNA accumulation. These same agents inhibited constitutive secretion of C1q in the absence of IFN-γ priming as determined by autoradiographic analysis of metabolically radiolabeled secretory C1q. Triggering of IFN-γ primed macrophages with LPS, IC, or AZ also markedly suppressed the increased rate of C1q secretion induced by IFN-γ in a dose-related fashion. A corresponding dose-dependent increased accumulation of endogenous C1q in cell lysates was detected by Western blot analysis of macrophages which had been stimulated by LPS, IC, or AZ alone or in combination with IFN-γ. Our findings indicate that LPS as well as FcR and C3bR triggering agents stimulate early and sustained C1q synthesis accompanied by an early and short-lived burst of C1q secretion which rapidly diminished and results in an increased intracellular accumulation of C1q due to ongoing synthesis. IFN-γ appeared to further amplify the same kinetics of increased C1q mRNA accumulation and decreased extracellular accumulation mediated by LPS, IC, and ZM. Our results suggest that LPS, IC, and AZ alone or in combination with IFN-γ stimulate early C1q production to modulate macrophage effector functions followed by an inhibition of C1q secretion when the activation process has been culminated.
Protein kinase C isoforms in human neutrophil cytoplasts
Authors: Smallwood Joan I , Malawista Stephen E
Published: January 2018

Granule-poor human neutrophil cytoplasts, prepared without heat or cytochalasin B treatment so as to preserve both motile function and activatable respiratory burst oxidase, were investigated for their content of several isoforms of protein kinase C (PKC). Immunoblotting with isoform-specific rabbit antibodies (Abs) to PKC revealed that both the α-specific and the β(I and II)-specific Abs recognized a protein band of 78 kd comigrating with PKC from rat brain cytosol. The γ-specific antiserum did not detect any protein of this molecular mass. The cytoplast β-PKC band was more readily detected than the cytoplast α-PKC band. Antibodies to βI- or β-II-specific PKC sequences showed the βII subtype to be the predominant form of β-PKC, although some βI was also found. The identity of the 78-kd cytoplast bands as PKC was established by the fact that phorbol ester treatment of intact cytoplasts induced translocation of the bands from cytosol to membrane fractions. However, whereas PKC specific activity was similar in cytoplast lysates and brain cytosol, immunoreactivity of cytoplast α- and β-PKC bands was considerably less than that of rat brain. Hydroxylapatite chromatography of partially purified cytoplast PKC revealed two major peaks of PKC activity precisely coeluting with brain a- and β-PKC and displaying comparable enzymatic activities despite the relatively weak immunoreactivity of cytoplast α- and β-PKC. To our knowledge, this is the first demonstration that human neutrophil–derived cytoplasts contain α, βI, and βII forms of PKC and that each isoform translocates from cytosol to membrane upon exposure to phorbol ester at concentrations that induce superoxide production. In addition, our evidence raises the possibility that cytoplasts may also possess other isoforms of PKC that we are unable to detect with our α, β, and γ antibodies. Finally, the granule-poor cytoplasts seem a particularly useful preparation in which to examine the role of individual PKC isoforms in neutrophil activation.
Chronic granulomatous disease with partial deficiency of cytochrome b558 and incomplete respiratory burst: variants of the X-linked, cytochrome b558-negative form of the disease
Authors: Roos Dirk , de Boer Martin , Borregard Niels , Bjerrum Ole W , Valerius Niels H , Soger Reinhard A , Mühlebach Tony , Belohradsky Bernd H , Weening Ron S
Published: January 2018

Five male patients from four different families presented with a clinical record of chronic granulomatous disease (CGD): recurrent infections of the skin and/or respiratory tract with catalase-positive microorganisms, sometimes in combination with granulomata and/or abscesses in various organs. These patients differed from “classical” forms of the disease in that their neutrophils, although deficient in killing in vitro of Staphylococcus aureus, contained a decreased but measurable amount of cytochrome b558 (10–60% of normal on a heme basis), causing weak staining in the nitroblue tetrazolium dye test and a depressed respiratory burst after contact of the cells with fluid or particulate activators of the NADPH:O2 oxidoreductase. In the cell-free activation system, the defect in the patients' cells was localized in the membrane fraction. In each of the four families, the cellular abnormalities showed an X-linked inheritance. Fusion experiments performed with the monocytes from these patients and those from patients with classical X-linked, cytochrome b558–negative (Xb0) or autosomal, cytochrome b558–positive (Ab+) CGD showed complementation of NADPH:O2 oxidoreductase activity in the latter but not in the former combination. Thus, the unusual CGD patients represent variant forms of Xb0 CGD, with mutations in the gene coding for the beta subunit of cytochrome b558 that do not cause complete loss of this protein.
Expression and distribution of CD11a/CD18 and CD54 during human T cell–B cell interactions
Authors: Tohma Shigeto , Ramberg Jane E , Lipsky Peter E
Published: January 2018

Interactions between intercellular adhesion molecule 1 (ICAM-1, CD54) and leukocyte function–associated antigen 1 (LFA-1, CD11a/CD18) play a critical role in T cell–B cell collaboration. The current experiments were carried out to determine the expression and distribution of these adhesion molecules on human peripheral T cells and B cells during T cell–B cell collaboration. Resting CD4+ T cells were largely ICAM-1 negative, whereas immobilized anti-CD3 monoclonal antibody (mAb) rapidly induced ICAM-1 expression. By contrast, most B cells expressed ICAM-1 before activation, and further increases in density were noted with stimulation. Both B cells and CD4+ T cells expressed LFA-1 before activation, although the density on CD4+ T cells was considerably greater. A double staining method for electron microscopic analysis was developed that permitted analysis of the expression and distribution of ICAM-1 to be assessed during T cell–B cell collaboration. Under the experimental conditions examined, B cells showed a uniform distribution of ICAM-1. In contrast, ICAM-1 was highly mobile on the surface of CD4+ T cells. If the T cells were not fixed, staining, even at 4°C, caused rapid redistribution of ICAM-1 into aggregates. However, by fixing cells before the staining procedures, the distribution of ICAM-1 on CD4+ T cells could be accurately assessed. Most (85%) of the fixed activated CD4+ T cells showed a uniform distribution of ICAM-1. However, when activated CD4+ T cells were cocultured with B cells, redistribution of ICAM-1 on CD4+ T cells but not B cells occurred, such that the majority (85%) was found at or immediately adjacent to the point of attachment to the B cells. No redistribution of LFA-1 on either T cells or B cells was found. These findings suggest that rapid changes in density of ICAM-1 expression and the mobility of ICAM-1 on activated T cells may play a role in providing activation signals to B cells during T cell–B cell collaboration.
Effects of glucocorticoids on the TPA-induced monocytic differentiation
Authors: Hoff Torsten , Spencker Torsten , Emmendoerffer Andreas , Goppelt-Struebe Margarete
Published: January 2018

The human monocytic cell line U937 was used as a model system to investigate the effects of glucocorticoids on monocytic differentiation. Upon incubation with the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) (5 × 10-9 M) for 48 to 72 h, the immature U937 cells ceased to proliferate and became morphologically and functionally macrophage-like. Preincubation of the cells with glucocorticoids (dexamethasone and prednisolone, 10-7 and 10-6 M) but not progesterone (10-6 M) had marked effects: The cells remained in suspension and developed very little cell-cell interaction. This correlated with decreased expression of the surface molecules ICAM-1 and CD18 as determined by fluorescence-activated cell sorter analysis. The TPA-induced ability of the cells to release lysozyme or to generate reactive oxygen radicals (determined as reduction of nitroblue tetrazolium) was markedly reduced. The induction of cyclooxygenase activity and thus the ability to release prostanoids was almost completely abolished. Inhibition of prostanoid synthesis was also observed when the glucocorticoids were administered 24 or 48 h after TPA. The primary step of TPA induction, the activation and translocation of protein kinase C, however, was not affected by glucocorticoids as determined by activity measurements and Western blot analysis. There was no change in the subsequent TPA-induced induction of c-fos. The down-regulation of the differentiation-related oncogenes c-myc and c-myb was the same in cells treated with TPA in the presence or absence of glucocorticoids. Furthermore, no significant effect of glucocorticoids on the TPA-induced growth arrest was observed. Glucocorticoids thus interfere with TPA-induced functions, which are typical for activated macrophages; however, they do not impair the differentiation process and concomitant growth inhibition.
Effects of antiorthostatic suspension and corticosterone on macrophage and spleen cell function
Authors: Kopydlowski Karen M , McVey D Scott , Woods Keith M , Landolo John J , Chapes Stephen K
Published: January 2018

The purpose of this study was to determine whether antiorthostatic suspension of C3HeB/FeJ mice for a period of 11 days affected macrophage and spleen cell function. We found that antiorthostatic suspension did not alter macrophage secretion of prostaglandin E2, tumor necrosis factor α, and interleukin-1. Antiorthostatic suspension also did not affect macrophage-mediated contact-dependent cytotoxicity, TNF-mediated cytotoxicity, expression of class II histocompatibility molecules, or concanavalin A and Bandeiraea simplicifolia lectin binding sites. The proliferative response of splenic T cells in response to mitogens and staphylococcal exotoxins was significantly enhanced in antiorthostatically suspended mice. We detected significantly higher concentrations of corticosterone in the plasma of antiorthostatically suspended mice. Therefore, there did not appear to be any direct immunosuppressive effects of corticosterone on the parameters tested.
Lectinophagocytosis of type 1 fimbriated (mannose-specific) Escherichia coli in the mouse peritoneum
Authors: Bernhard Wolfgang , Gbarah Awni , Sharon Nathan
Published: January 2018

Bacteria can bind specifically to phagocytic cells via lectin-carbohydrate interactions and such binding is often followed by activation and degranulation of the phagocytes, as well as uptake and killing of the bacteria, a phenomenon designated lectinophagocytosis. Although extensively studied in vitro, no direct evidence for the occurrence of lectinophagocytosis in vivo has been available. To obtain such evidence, we injected type 1 fimbriated (mannose-specific) or nonfimbriated Escherichia coli into the peritoneal cavity of mice (107–1010 bacteria/animal) in the absence or presence of sugars and quantified the phagocytic activity by assaying the release of lysosomal N-acetyl-β-d-glucosaminidase into the peritoneal fluid, up to 45 min after injection. Following injection of the type 1 fimbriated bacteria, significant release of the enzyme was observed which was time dependent and increased with the number of bacteria injected, whereas the nonfimbriated bacteria caused only little release. Methyl α-d-mannoside (50 mM), but not methyl α-d-galactoside or sucrose, inhibited the release by 60 to 100%. No release of N-acetyl-β-d-glucosaminidase was induced by bacteria injected into a peritoneal cavity from which the macrophages had been removed. Our findings show that lectinophagocytosis can occur in vivo and may contribute to the host's defence against type 1 fimbriated bacteria.
Quartz selectively down-regulates CR1 on activated human granulocytes
Authors: Lundahl J , Dahlgren C , Eklund A , Hed J , Hernbrand R , Tornling G
Published: January 2018

We have investigated the interaction between quartz and granulocytes with respect to complement receptor expression. When N-formylmethionyl-leucyl- phenylalanine (fMLP)-stimulated leukocytes were exposed to quartz at 37°C, CR1 was down-regulated but CR3 was not affected. This was a direct effect on granulocytes because it occurred in a similar fashion when mixed leukocyte suspensions and isolated granulocyte populations were used as targets for quartz. The observed down- regulation by quartz was not affected by the microfilament-disrupting agent cytochalasin B and the total detectable pool of CR1 was reduced after quartz exposure. When protease inhibitors, such as aprotinin or phenylmethanesulfonyl fluoride, were present during quartz exposure, the down-regulation of GR1 was less pronounced, but this was not the case not when protease inhibitors such as £DTA-Na2 and pepstatin were present. Exposure to quartz was not accompanied by a pronounced release of β-glucoronidase (marker for the rprimary granules) or vitamin B12 binding protein (mar- er for the secondary granules). In contrast to quartz, exposure to alumina did not affect the expression of CR1 and CR3. The spontaneous mobilization of CR1 at 37°G was reduced when quartz was present but the GR3 mobilization was unaffected. Our results indicate that quartz induces a granule protease-dependent selective shedding of CR1 but not CR3 despite a low degree of degranulation. J. Leukoc. Biol. 53: 99–103; 1993.
Differential expression of bovine MHC class II antigens identified by monoclonal antibodies
Authors: Taylor Bernadette C , Choi K Yeon , Scibienski Robert J , Moore Peter F , Stott Jeffrey L
Published: January 2018

Four monoclonal antibodies (mAbs), UC-A4, UC-D3, UC-H9, and IL-A21, specific for bovine major histocompatibility complex class II proteins are described. Sequential immunoprecipitation experiments using biotin-labeled peripheral blood mononuclear cells suggested, but did not conclusively establish, that each of these antibodies recognized a different epitope. The epitope identified by IL-A21 appeared to be common to all of the class II proteins precipitated by the four mAbs, and UG-D3 and UC-H9 each appeared to react with distinct epitopes on separate subsets of these class II proteins. Monoclonal antibody UC-A4 appeared to identify an epitope on a subset of the class II molecules identified by UC-H9. Differences found in the expression by lymphoid cells of class II proteins identified by the four mAbs were indicative of each mAb recognizing a different epitope. UC-H9 and IL-A21 class II proteins were detected on all surface immunoglobulin (S’lg) positive cells in peripheral blood, but UC-A4 and UC-D3 class II proteins were not. Expression of UC-A4 class II proteins, detected at low density on a strikingly reduced number of S’lg+ cells from the blood of some bovine leukosis virus-infected cattle, could be increased by culturing these B cells with lipopolysaccharide. All peripheral blood monocytes expressed UG-H9 and IL-A21 class II proteins, but only a proportion of monocytes expressed detectable UC-A4 and UG-D3 class II proteins. Almost all mitogen-stimulated BoCD4+ and BoCD8+ T cells expressed UC-H9 and IL- A21 class II proteins, whereas fewer stimulated T cells of both subsets expressed UC-A4 and UC-D3 class II proteins. All gamma/delta receptor (γ/δ R) T cells expressed UC-D3, UG-H9, and IL-A21 class II proteins, but no cells (of γ/δ R+ or CD4+/CD2+ phenotype) from γ/δ R+ T cell-enriched cultures expressed UC-A4 class II proteins. J. Leukoc. Biol. 53: 479–489; 1993.
Analysis of differential HLA-DQB expression in autologous B cell lines
Authors: Woolfrey Ann E , Andersen L Christina , Shewey Linda , Chung JoSan , Nepom Gerald T
Published: January 2018

Glass II major histocompatibility complex genes are differentially expressed during cellular activation and differentiation, often in a locus-specific manner. We investigated the differential expression of the HLA- DQB gene, using B cell lines LAZ221 and LAZ388: LAZ221, derived from an early B cell leukemia, expresses HLA-DR but not HLA-DQ LAZ388, the autologous Epstein-Barr virus-transformed B cell line, expresses both DR and DQ Transfection experiments demonstrate differential function of class II gene upstream regulatory regions in the two lines, which correlates with differential class II gene expression. Using gel retardation and DNase I footprint assays, we demonstrate that absence of DQB gene expression is associated with characteristic nuclear protein-binding interactions in the proximal DQB gene upstream regulatory region. These interactions are visualized as DNA-protein complexes that are seen with nuclear proteins from the DQ-negative cell line, LAZ221, and involve consensus promoter Y box and W box elements, as well as novel upstream sites. Transcriptional regulatory proteins that differ in these autologous B cell lines may be stage-specific factors involved in the developmental regulation of HLA genes. J. Leukoc. Biol. 53: 697–706; 1993.
Effects of in vitro exposure to arachidonic acid on TNF-α production by murine peritoneal macrophages
Authors: Hubbard Neil E , Lim Debora , Somers Scott D , Erickson Kent L
Published: January 2018

Modifying the fatty acid composition of macrophages through diet can significantly alter some of their functions, such as tumoricidal capacity and tumor necrosis factor a (TNF-α) production. The mechanism of that modification, however, is unknown. In this report, we provide evidence that fatty acids added to macrophages in culture can significantly alter macrophage TNF-α production. For example when inflammatory macrophages were incubated with various doses of arachidonic acid [20:4(n-6)] during activation with lipopolysaccharide (LPS), we observed a dose-dependent decrease in the level of bioactive TNF-α with complete inhibition at 2-5 μΜ. This inhibition was specific for 20:4(n-6) because in vitro treatment with other fatty acids, such as eicosapentaenoic [20:5(n-3)] or docosahexaenoic [22:6(n-3)] acids, had differential effects. The inhibitory action of 20:4(n-6) did not involve toxicity because cell viability was not affected and in vitro interferon-γ and lipopolysaccharide (LPS) activation of macrophages for killing of P815 tumor targets was not altered. Inhibition by 20:4(n-6) occurred posttranscriptionally, and could be reversed when macrophages were treated with indomethacin during activation. Arachidonic acid treatment also significantly increased the production of immunoreactive prostaglandin E2 (PGE2) by LPS-treated and untreated macrophages. These results suggest that in vitro treatment of macrophages with 20:4(n-6) may inhibit TNF-α production through an alteration in the levels of PGE2 at a posttranscriptional level. These results provide evidence that some dietary fats may affect macrophage activity through modification of eicosanoid synthesis.
Calcium-binding myeloid protein (P8,14) is phosphorylated in fMet-Leu-Phe-stimulated neutrophils
Authors: Bengis-Garber Carmela , Gruener Nachman
Published: January 2018

In this report, we show that the pl4 subunit of calcium-binding myeloid protein complex (p8,14) is phosphorylated in human neutrophils stimulated with either fMet-Leu-Phe, phorbol myristate acetate, or a calcium ionophore. Trifluoperazine, a calmodulin antagonist, caused hyperphosphorylation of pi 4 in intact resting neutrophils. Freincubation of resting cells with 10-20 nM calyculin A, a potent protein phosphatase inhibitor, also caused enhanced labeling of pi 4, which was further progressively increased on stimulation with fMLP. Thus, the phosphorylation level of pi 4 in resting as well as in stimulated neutrophils appears to be controlled by an active protein phosphatase. The phosphorylation of pi 4 by a chemoattractant and by a phorbol ester is a novel finding supporting the current belief that p8,14 myeloid protein may play an important role in the metabolism of myeloid cells.
Immune changes during short-duration missions
Authors: Taylor Gerald R
Published: January 2018

Spaceflight materially influences the immune mechanism of humans and animals. Effects resulting from missions of less than 1 month are examined. Effects from longer missions are discussed in the companion paper by Konstantinova et al. Most immunology studies have involved analyses of subjects and samples from subjects obtained after flight, with the data being compared with similar data obtained before flight. These studies have demonstrated that short-duration missions can result in a postflight depression in blast cell transformation, major changes in cytokine function, and alterations in the relative numbers of immune cell populations. In addition to these post- vs. preflight studies, some data have been produced in flight. However, these in vitro analyses have been less than satisfactory because of differences between in-flight and ground-control conditions. Recently, both the U.S. and Russian space programs have started collecting in-flight, in vivo, cell-mediated immunity data. These studies have confirmed that the human cell- mediated immune system is blunted during spaceflight.
A single exogenous stimulus activates resident rat macrophages for nitric oxide production and tumor cytotoxicity
Authors: Lavnikova Natasha , Drapier Jean-Claude , Laskin Debra L
Published: January 2018

Based on experiments with mouse cells, it appears that macrophage activation for cytotoxicity requires two exogenous signals. One signal primes or sensitizes the cells, while the second activates them for killing. The present studies were designed to analyze the capacity of rat macrophages to be activated for nitric oxide production and for cytotoxicity by different inflammatory stimuli. We found that both resident alveolar macrophages (AMs) and resident peritoneal macrophages (PMs) from Sprague-Dawley rats produced nitric oxide in response to relatively low doses of a single exogenous activating stimulus [interferon-γ (IFN-γ) or lipopolysac- charide (LPS)]. Resident PMs treated with either of these agents alone also exhibited nitric oxide-mediated cytotoxicity toward xenogeneic and allogeneic tumor targets. In contrast to results reported previously with both resident and elicited PMs from mice, tumor necrosis factor-α (TNF-α) exerted only a small enhancing effect on IFN-γ-induced nitric oxide production by resident rat PMs. In addition, although some level of cooperativity between IFN-γ and LPS was observed at low concentrations of LPS (< 10 ng/ml), IFN-γ did not augment the effects of higher concentrations of LPS (≥10 ng/ml) on nitric oxide production by PMs. In contrast to PMs, AMs had a strong synergistic response to combinations of IFN- γ and LPS or TNF-α but also only at relatively low concentrations of IFN-γ and LPS. Furthermore, maximum nitric oxide production induced by IFN-γ in these cells could be enhanced by TNF-α or low doses of LPS. However, as observed with PMs, combinations of IFN-γ and higher doses of LPS did not significantly augment maximum nitric oxide production induced in AMs by LPS alone. Thus, our data suggest that resident rat PMs and AMs resemble elicited mouse PMs in their ability to respond to a single activating stimulus. However, PMs and in some respects AMs differ from the latter by their reduced responsiveness to combinations of activators. Taken together, our results suggest that two exogenous stimuli are not required for full activation of resident macrophages from Sprague-Dawley rats.
Antirheumatic gold compounds and penicillamine enhance protein kinase C-mediated activation of the arachidonate- mobilizing phospholipase A2 in mouse macrophages
Authors: Bondeson Jan , Sundler Roger
Published: January 2018

The effects of antirheumatic gold compounds and D-penicillamine on protein kinase C- and Ca2+- mediated activation of arachidonate mobilization and the formation of eicosanoids in mouse macrophages have been investigated. Auranofin (0.2-2 μΜ) enhanced the response to phorbol ester two- to three-fold, and similar enhancement was caused by aurothiomalate, aurothioglu- cose, and penicillamine, but only after pretreatment for 1-4 h. The enhanced mobilization of arachidonate was accompanied by increased formation and release of prostaglandin E2 and 6-keto prostaglandin Flα, but not of lipoxygenase metabolites. No such enhancement occurred when the arachidonate-mobilizing phospholipase A2 was activated directly (calcium ionophore A23187). Instead, auranofin caused selective inhibition of calcium ionophore-induced formation of leukotriene C4. Treatment of macrophages with 4β-phorbol 12-myristate 13-acetate causes a rapid increase in the phosphorylation and a 1.4-1.8-fold increase in the activity of the 85-kd arachidonate-mobilizing phospholipase A2 as determined in an in vitro assay. The increase in activity was further enhanced by both the gold compounds and penicillamine. These findings indicate that the target for the enhancing effect of the antirheumatic drugs is located between protein kinase C and phospholipase A2 in the signal chain leading to activation of the latter enzyme.
Transforming growth factor β1 regulation of macrophage activation depends on the triggering stimulus
Authors: Corradin Sally Betz , Buchmuller-Rouiller Yolande , Smith Josiane , Suardet Laurent , Mau§l Jacques
Published: January 2018

We have examined the effects of transforming growth factor β1 (TGF-β1) on the regulation of murine bone marrow-derived macrophage function. TGF-β, added simultaneously with or up to 4 h before interferon-γ (IFN-γ) plus lipopolysaccharide (LPS), inhibited macrophage leishmanicidal activity, nitrite (NO2”) production, and secretion of prostaglandin E2. In contrast, no effect of TGF-β could be demonstrated on macrophages stimulated with IFN-γ plus tumor necrosis factor-γ (TNF-γ) under the same conditions. These results suggested that TGF-β inhibited LPS-induced triggering of macrophage activation, which was confirmed by studies with IFN- γ-primed cells. Interestingly, when macrophages were pretreated with TGF-β for 24 h, NO2− production in response to IFN-γ plus TNF-α was also inhibited. Although control and IFN-γ/LPS-stimulated macrophages were found to secrete latent TGF-β, only the IFN- γ/LPS cultures produced biologically active TGF-β. Significantly, active TGF-β was present at concentrations shown earlier to inhibit macrophage function.
Random depletion of T cells that bear specific T cell receptor Vβ sequences in AIDS patients
Authors: Boldt-Houle Deborah M , Rinaldo Charles R , Ehrlich Garth D
Published: January 2018

A cross-sectional PCR analysis of the TCR Vβ repertoires in HIV-1 seronegative controls and HIV-1 infected individuals with either clinically or immunologically defined AIDS [1] was performed to examine the proposed superantigen model for HIV-1 pathogenesis. In contrast to previous reports, we find neither uniform specific losses nor uniform clonal expansions of particular TCR Vβ gene families in subjects with AIDS. Instead our study, which was designed specifically to qualitatively determine the presence or absence of TCR Vβ families in both subject populations, indicates an overall diminution in the expression of TCR Vβ gene families in HIV-1 infected individuals with AIDS compared with controls. This is commensurate with the decrease in CD4 T cells in the AIDS population. Our data are therefore not directly suggestive of a common superantigen model of HIV-1 induced T cell clonal depletion or anergy, but instead emphasize a broad decrease in signals throughout the TCR Vβ repertoire in AIDS versus control groups. This random depletion in the TCR Vβ repertoire is most likely caused by aspects of HIV-1 pathogenesis other than virus- encoded superantigens.
Flow cytometric analysis of the cytotoxic effects of Actinobacillus actinomycetemcomitans leukotoxin on human natural killer cells
Authors: Shenker Bruce J , Vitale Laura A , Keiba Irene , Harrison Gerald , Berthold Peter , Golub Ellis , Lally Edward T
Published: January 2018

The goal of this investigation was to determine if human natural killer (NK) cells were susceptible to the cytolytic effects of the Actinobacillus actinomycetemcomitans leukotoxin (LTX). Following treatment with LTX (0–200 ng/ml), NK cell activation by interleukin-2 (IL-2) was evaluated. LTX inhibited the IL-2-induced expression of both CD69 and the IL-2 receptor. Furthermore, the up-regulation of CD56 was also impaired. To determine whether the observed functional deficits were the result of cell death, NK cell viability was evaluated by flow cytometry. Changes in forward and side light scatter patterns consistent with cell death were observed within 60 min. Direct analysis of cell viability by measuring propidium iodide exclusion, however, indicated little change in the viability of LTX-treated NK cells. Electron microscopic analysis of NK cells exposed to LTX revealed early nuclear alterations characterized by hyperchromaticity, nuclear fragmentation, and condensation of nucleoplasm. However, no change in membrane integrity was initially noted. Finally, LTX caused a rapid and sustained elevation in the intracellular levels of Ca2+. These morphological and biochemical changes are consistent with the notion of programmed cell death. J. Leukoc. Biol. 55: 153–160; 1994.
Elimination of macrophages by liposome-encapsulated dichloromethylene diphosphonate suppresses the endotoxin-induced priming of Kupffer cells
Authors: Bautista Abraham P , Skrepnik Nebosja , Niesman Michael R , Bagby Gregory J
Published: January 2018

This study was performed to elucidate the role of Kupffer cells during endotoxemia by assessing the consequences of macrophage depletion by liposome-encapsulated dichloromethylene diphosphonate (L-DMDP) following lipopolysaccharide (LPS) treatment. Results show that more than 90% of the largest Kupffer cells, arbitrarily termed KC3, were eliminated, while only 50% of the smaller Kupffer cells were depleted. The selective elimination of a subpopulation of Kupffer cells was accompanied by a significant attenuation of endotoxin (LPS)-induced serum tumor necrosis factor activity by almost 90%. Hepatic sequestration of neutrophils into the liver after LPS injection was not altered by L-DMDP. The priming action of LPS on superoxide release by neutrophils recovered from the liver in response to in vitro PMA or zymosan was not altered by L-DMDP. However, the LPS-induced priming of superoxide formation in vitro by Kupffer cells, particularly KC3, was significantly attenuated. These results indicate that selective elimination of a subpopulation of Kupffer cells by L-DMDP down-regulates the LPS-induced cytokine release in vivo and endotoxin-mediated priming of hepatic macrophages for enhanced formation of toxic oxygen metabolites. However, biological activities of neutrophils (i.e., superoxide release and hepatic sequestration) are not altered by L-DMDP, further emphasizing the specificity of L-DMDP action on Kupffer cells. J. Leukoc. Biol. 55: 321–327; 1994.
Thymic peptide modulates glutathione redox cycle and antioxidant enzymes in macrophages
Authors: Sil Park Choon , Li Lin , Lau Benjamin H S
Published: January 2018

The effect of a 6-kDa thymic peptide (TP) on the oxidative burst of the murine macrophage cell line J774 was determined. TP was incubated with J774 cells at 37° and 5% CO2 for 18 h, oxidative burst was triggered by zymosan, and chemiluminescence was amplified by luminol and measured in an automated luminometer. TP exhibited a concentration-dependent suppression of oxidative burst. To study the mechanisms involved in TP’s suppression of oxidative burst, its effect on the glutathione redox cycle and antioxidant enzymes was investigated. J774 cells were incubated with varying concentrations of TP for 18 h, washed, resuspended in phosphate-buffered saline, and sonicated to obtain cell lysate. Biochemical assays were performed with the lysate. TP was shown to increase the level of glutathione, and activities of glutathione-peroxidase and glutathione-reductase, indicating its ability to modulate the glutathione redox cycle. The activity of antioxidant enzyme superoxide dismutase was enhanced significantly by TP treatment while catalase activity remained unaffected. These results suggest that TP possesses an antioxidant property and therefore may be involved in the regulation of free radical mediated reactions. J. Leukoc. Biol. 55: 496–500; 1994.
HOCI production by human neutrophils activated by surface-associated IgG: Requirement for influx of extracellular calcium
Authors: Blackburn Warren D , Chatham W Winn
Published: January 2018

Neutrophils produce large quantities of HOCI when stimulated by surface-associated immunoglobulin G, a result not seen when neutrophils are stimulated with soluble complexes of IgG. Compared with unactivated cells or cells stimulated with soluble aggregates of IgG, a significant influx of extracellular 45Ca2+ was observed in cells activated by surface-associated IgG. Removal of extracellular calcium with EGTA almost completely blocked HOCI production. Similarly, treatment of neutrophils with lanthanum, which has been shown to interfere with calcium channels, also effectively blocked HOCI production. These results were not secondary to an overall decrease in activation, as superoxide production and release of the specific granule protein lactoferrin and the azurophilic granule protein myeloperoxidase were not significantly altered by lanthanum or EGTA. Production of H2O2, the precursor of HOCI, was similarly decreased by both EGTA and lanthanum. Induction of extracellular calcium influx with a calcium ionophore in the presence of soluble aggregates of IgG resulted in HOCI production. Production of HOCI is not sensitive to inhibition by pretreatment of cells with pertussis toxin. These observations indicate that the differences in the biological responses of human neutrophils to surface-associated IgG compared with soluble aggregates of IgG are associated with differing signaling events, including influx of extracellular calcium. J. Leukoc. Biol. 55: 793–797; 1994.
Phenotypic and functional activation of monocytes in HIV-1 infection: interactions with neural cells
Authors: Birdsall Holly H , Trial JoAnn , Hallum Jennifer A , de Jong Andrew L , Green Linda K , Bandres Juan C , Smole Sandra C , Laughter Arline H , Rossen Roger D
Published: January 2018

To investigate mechanisms that facilitate transendothelial migration of HIV-infected leukocytes and their interactions with neural tissues early in the disease, we studied peripheral blood from Centers for Disease Control class A patients. Patients’ monocytes displayed increased quantities of the adhesion molecules CD11a, CD11b, and very late antigen 4 (VLA-4). Expression of these correlated directly with the numbers of monocytes that migrated through confluent endothelium. These ligands also mediated leukocyte interactions with cultured human neural cell lines. Although patients’ cells bound in greater numbers, there was no evidence of target cell injury. To evaluate the direct effect of HIV-1 on monocyte neuroadhesion, we compared infected with uninfected monocytoid (U-937,THP-1) and T lymphoblastoid (MT-4) cell lines. HIV infection increased the neuroadhesiveness of monocytoid lines only. By using lines with more than 95% HIV-infected cells, we demonstrated that HIV-1 gp120 participates with lymphocyte function-associated antigen 1 and VLA-4 to mediate monocyte-neural cell interactions. J. Leukoc. Biol. 56: 310–317; 1994.
IL-4 and IL-13 have overlapping but distinct effects on HIV production in monocytes
Authors: Mikovits Judy A , Meyers Anne M , Ortaldo John R , Minty Adrian , Caput Daniel , Ferrara Pascual , Ruscetti Francis W
Published: January 2018

In HIV-1-infected monocytes and monocytoid cell lines, viral expression can be observed as high-level production, restricted (chronic low-level) expression, and latency (no viral expression). Interleukin-13 (IL-13) and IL-4, which have remarkedly similar deactivating effects on inflammatory monocyte functions, were studied for their regulation of HIV expression in monocytes. Pretreatment of peripheral monocytes for 48–72 h with IL-13 markedly decreased acute HIV infection, whereas IL-4 increased it. Similar effects were seen when the U1 and R-THP-1 monocytoid cell lines with restricted HIV expression were treated with these cytokines. However, when these continuously producing cell lines were chronically treated with cytokines, IL-13 increased HIV production. Neither IL-4 nor IL-13 stimulated HIV expression in latently infected cells. In chronically infected cells, several cytokines reduced viral mRNA. Both IL-4 and IL-13 increased monocyte aggregate formation, but only IL-4 ultimately stimulated cytolysis of HIV-infected monocytes as well as increased apoptosis of U1. In the presence of tumor necrosis factor α or IL-6, which upregulate HIV expression, IL-13 could no longer suppress HIV expression. These results indicate that IL-4 and IL-13, although closely related in modulating monocyte function, can have divergent effects on HIV expression in monocytes. Collectively, these data suggest that there exists a complex cytokine tissue environment with positive regulators of HIV expression able to override negative regulators. J. Leukoc. Biol. 56: 340–346; 1994.
Pasteurella haemolytica leukotoxin—induced synthesis of eicosanoids by bovine neutrophils in vitro
Authors: Clinkenbeard Kenneth D , Clarke Cyril R , Hague Christinia M , Clinkenbeard Patricia , Srikumaran S , Morton Rebecca J
Published: January 2018

Exposure of isolated bovine neutrophils to partially purified Pasteurella haemolytica leukotoxin caused increased synthesis of leukotriene B4 (LTB4) but not thromboxane B2 (TXB2) from endogenous arachidonic acid. Synthesis of LTB4 was closely correlated with leukotoxin-induced neutrophil lysis. At low toxin concentrations, LTB4 production lagged behind leukotoxin-induced neutrophil lysis over a 3-h period. The neutralizing monoclonal antileukotoxin antibody MM601 neutralized both leukotoxin-induced neutrophil lysis and LTB4 synthesis. Both leukotoxin-induced neutrophil lysis and LTB4 synthesis were Ca2+-devendent. When leukotoxin-induced LTB4 synthesis from exogenous arachidonic acid was examined, significant LTB4 synthesis occurred at 5 min of leukotoxin exposure, which was before leukotoxin-induced lysis developed. Leukotoxin-induced LTB4 synthesis from endogenous arachidonic acid appears to require leukotoxin-induced plasma membrane damage (occurring during neutrophil lysis), whereas LTB4 synthesis from exogenous arachidonic acid is initiated rapidly and occurs in the absence of plasma membrane damage. J. Leukoc. Biol. 56: 644–649; 1994.
Surface IgM-stimulated proliferation, inositol phospholipid hydrolysis, Ca2+ flux, and tyrosine phosphorylation are not altered in B cells from p59fyn-/- mice
Authors: Sillman Amy L , Monroe John G
Published: January 2018

The surface immunoglobulin M (sIgM)-associated src family protein tyrosine kinases (PTKs) p55blk, p59fyn, and p53/56lyn become activated in B cells within seconds following sIgM cross-linking. Studies using protein tyrosine kinase (PTK) inhibitors have demonstrated that PTK activity is crucial for downstream events such as calcium flux, inositol phospholipid hydrolysis, and cell cycle entry. The roles that the individual src family PTKs play in sIgM signaling are largely unknown, however. In order to determine whether p59fyn plays a distinct role in sIgM signal transduction, the signaling capabilities of B cells isolated from fyn “knockout” mice were evaluated. We observed that in the absence of p59fyn, there was no demonstrable compromise of the slgM-coupled signaling events measured (tyrosine phosphorylation, inositol phospholipid hydrolysis, and Ca2+ flux). We propose that either p59fyn is not involved in coupling sIgM to these specific signaling pathways or that other PTKs are able to compensate for the absence of p59fyn, indicating redundancy in the sIgM signaling pathways. J. Leukoc. Biol. 56: 812–816; 1994.
Review of the macrophage disappearance reaction
Authors: Barth Malcolm W , Hendrzak Jill A , Melnicoff Meryle J , Morahan Page S
Published: January 2018

Macrophages (Mφs) undergo a physiological response known as the macrophage disappearance reaction (MDR) in response to certain stimuli in the peritoneal compartment. The types of stimuli that can cause the MDR, the relationship of the MDR to the host immunological response, and the possible role of the MDR in Mφ activation are reviewed. The data indicate that the MDR occurs in response to both acute nonspecific inflammatory and specific immune delayed hypersensitivity processes and that the MDR may play an important role in Mφ activation. J. Leukoc. Biol. 57: 361–367; 1995.
Cloning and characterization of a novel cDNA that is IFN-γ-induced in mouse peritoneal macrophages and encodes a putative GTP-binding protein
Authors: Lafuse William P , Brown David , Castle Lynn , Zwilling Bruce S
Published: January 2018

Macrophage activation by IFN-γ results in a cascade of gene expression. To identify genes activated in mouse peritoneal macrophages by IFN-γ, we created a cDNA subtraction library of IFN-γ-induced genes. We have isolated from this subtraction library a novel cDNA clone, called Mg21, whose mRNA is absent in unstimulated mouse peritoneal macrophages and is induced to high levels within 4 h following the addition of IFN-γ. Induction of Mg21 mRNA by IFN-γ occurred in the presence of cycloheximide, indicating that expression of Mg21 mRNA does not require protein synthesis. A small amount of Mg21 mRNA was also induced by LPS, but not by IL-2, IL-4, IL-10, or TNF-α. The DNA sequence of Mg21 is 1617 nucleotides and contains an open reading frame that codes for a protein of 415 amino acids with a predicted molecular weight of 47,106 Da. The predicted amino acid sequence lacks a signal sequence or transmembrane segments, indicating that the protein is an intracellular protein. Computer search of the GenBank and EMBL databases indicates that this cDNA clone is unique but has 57% sequence identity with IRG-47, which is a mouse gene induced by IFN-γ in pre-B and B lymphocyte cell lines. IRG-47 encodes an intracellular protein that contains three conserved protein motifs present in GTP-binding proteins. Analysis of the protein sequence of Mg21 showed that these three conserved protein motifs are also present in Mg21. J. Leukoc. Biol. 57: 477–483; 1995.