bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phorbol Ester-Induced Loss of Membrane Sialic Acid: Implications for Tumor Cytolysis by Natural Killer Cells
Authors: Nabi Zeenat F , Zucker-Franklin Dorothea , Baten Abdul 
Published: January 2018

Abstract
Freeze-fracture analysis has shown that treatment of cells with phorbol myristate acetate (PMA) results in a loss of intramembranous particles (IMP) associated with the external leaflet of their plasma membranes. It has also been demonstrated that phorbol esters markedly enhance the sensitivity of tumor targets to natural killer (NK) cells, although the mechanism underlying this phenomenon has remained unexplained. Since the ability of NK cells to recognize neoplasms appears to be inversely related to the concentration of sialic acid on the target cell surface, it seemed possible that phorbols affect membrane glycoproteins which have terminal carbohydrates bearing sialic acid residues. To investigate whether phorbol treatment could be responsible for the loss of sialic acid, four tumor cell lines were examined before and after exposure to PMA. A reduction in surface sialic acid was established by four different methods: 1) standard thiobarbituric acid analysis of cell hydsrolysates, 2) metabolic labelling of cells with [3H]-mannosamine followed by treatment with neuraminidase, 3) chromatography of membrane extracts, and 4) freeze-fracture analysis of lectin-labelled intact cells. These observations suggest a mechanism whereby phorbols may facilitate NK-cell-mediated cytolysis. In addition, an entirely novel effect of these tumor-producing agents may have been uncovered.
Beta-Carotene Stimulates Human Leukocytes to Secrete a Novel Cytokine
Authors: Abril Edward R , Rybski James A , Scuderi Philip , Watson Ronald R 
Published: January 2018

Abstract
The effect of beta-carotene on cytokine production by human peripheral blood leukocytes was tested. Beta-carotene stimulated the secretion of a novel cytotoxic cytokine when peripheral blood cells were exposed to carotenoid concentrations between 10-6 and 10-10M. Beta-carotene–treated supernatants caused the cytolysis of four out of the six human tumor cell lines tested. Low level toxicity was also observed when normal diploid fibroblast lines were exposed to beta-carotene–treated leukocyte supernatants. The cytotoxic activity elicited by beta-carotene was found to be distinct from characterized cytokines based on both antisera neutralization and target cell specificity studies. This study demonstrates that beta-carotene can induce human leukocytes to secrete one or more cytokines that can manifest cytotoxic activity against human tumor cells in vitro.
Lead Inhibits Intracellular Killing of Leishmania Parasites and Extracellular Cytolysis of Target Cells by Macrophages Exposed to Macrophage Activating Factor
Authors: Mauël Jacques , Ransijn Adriana , Buchmüller-Rouiller Yolande 
Published: January 2018

Abstract
Activation of Leishmania enriettii-infected mouse macrophages in vitro by treatment with macrophage activating factor (MAF)-rich media supplemented with lipopolysaccharide (LPS) leads to rapid killing of the microorganism. When exposed to MAF + LPS in the presence of 30-100 μM lead acetate, however, macrophages failed to destroy the parasites. This effect was not due to lead toxicity for macrophages. Decreased microbicidal activity correlated with depressed respiratory burst as determined by measurements of glucose oxidation through the hexose monophosphate shunt (HMPS). Lead had little effect on Intracellular parasite killing induced by exposure of macrophages to the electron carrier methylene blue; HMPS in such cells was similarly little affected, indicating that chemical triggering of this pathway bypassed the lead-imposed blockade. Lead also abolished macrophage activation measured by the lysis of tumor target cells in vitro. The metal failed, however, to interfere with target-cell lysis by macrophages activated in lead-free medium, suggesting that lead inhibited the acquisition of the activated state rather than the functional expression of such state. Lead did not prevent the binding of radiolabelled interferon-γ to macrophages; it did, however, slow down receptor turnover and degradation of bound interferon. Lead also inhibited the LPS-triggered cytotoxicity in macrophages previously exposed to interferon-γ in lead-free medium, suggesting that depressed intracellular killing might result from an effect on both the priming (interferon or MAF-dependent) and the triggering (LPS-dependent) steps of activation.
Inhibitory Effect of SV-IV, a Major Protein Secreted From the Rat Seminal Vesicle Epithelium, on Phagocytosis and Chemotaxis of Human Polymorphonuclear Leukocytes
Authors: Metafora Salvatore , Porta Raffaele , Ravagnan Gianpietro , Peluso Gianfranco , Tufano Maria Antonietta , De Martino Luisa , lanniello Raffaele , Galdiero Francesco 
Published: January 2018

Abstract
The effect of SV-IV, one of the major proteins secreted from the rat seminal vesicle epithelium, on phagocytosis and chemotaxis of human polymorphonuclear leukocytes (PMNs) has been studied. Various cytological, biochemical, metabolic, and physical correlates of both biological activities have been found to be markedly reduced by the presence in the medium of micromolar concentrations of protein SV-IV. Moreover, the Scatchard analysis of the labeled SV-IV binding to PMN cell surface has demonstrated that such binding is specific. The binding sites contain only saturable components, completely displaceable by unlabeled SV-IV. The number of the specific sites has been calculated to be 87,000/cell, with a Kd of 1.72 x 10-7 M. The molecular mechanism of the inhibitory effect is discussed along with the possible biological and clinical implications of the experimental findings.
Biologic and Immunohistochemical Analysis of Macrophage lnterleukin-1α, -1β, and Tumor Necrosis Factor Production During the Peritoneal Exudative Response
Authors: Chensue Stephen W , Shmyr-Forsch Christine , Weng Andrew , Otterness Ivan G , Kunkel Steven L 
Published: January 2018

Abstract
The present study examined changes in lipopolysaccharide (LPS)-induced interleukin 1 (IL-1) and tumor necrosis factor (TNF) production by murine peritoneal macrophages during the chronic exudative response to Freund’s complete adjuvant (CFA). Macrophages were isolated by peritoneal lavage and adherence at intervals over a 32 day period following i.p. injection of CFA. Optimal culture conditions for IL-1 and TNF production were predetermined, and it was found that IL-1 production was profoundly impaired at densities of above 150 cells/mm2, whereas TNF sythesis was more resistant to density effects. Using optimal conditions, we observed a sequential appearance of monokines. On day 0 there was minimal IL-1 production and no detectable TNF production. By days 4–7, IL-1 production reached maximum levels with a steady decline to baseline by day 32. TNF production steadily increased after day 2, reached maximal levels by days 16–20, and then partly declined by day 32. These findings were supported by kinetic analyses at specified days. When related to exudative events, it appeared that maximal IL-1 was associated with the recruitment stage of the reaction, whereas TNF production was associated with the established exudate. Immunohistochemical analysis revealed that TNF production could be related to the proportion of macrophages with cytoplasmic TNF expression. In contrast, IL-1α and -1β expression was comparable among populations with 85–100% of cells showing cytoplasmic expression 6 hr after LPS stimulus. Whereas cytoplasmic IL-1α persisted for the 18 hr study period, IL-1β disappeared from many adjuvant recruited cells. Our findings suggest that monokine production is orchestrated during macrophage recruitment and activation at sites of chronic inflammation.
Quantitation of the Host Cell Infiltration Kinetics of the Nonimmunogenic Colon 26 Tumor by Multiparameter Flow Cytometry
Authors: Sneed Rosie A , Stevenson Anita P , Stewart Carleton C 
Published: January 2018

Abstract
In this study, we examined the kinetics of host cell infiltration into the nonimmunogenic Colon 26 tumor. We found that 1 x 104 cells were required to produce tumors in 100% of mice. The in vivo doubling time was 42.5 h, and a barely palpable tumor contained 8 x 106 cells. No evidence of concomitant immunity was found. The number of host cells infiltrating the in vivo tumors increased at the same rate as the number of tumor cells, but averaged only 22% of total cells. Cycling T lymphocytes were present in the host cell infiltrate of this tumor. In addition, approximately 50% of in vivo Colon 26 cells were Thy-1.2 positive. The observed characteristic of low immunogenicity makes it a useful murine model for studying human malignant tumors.
Lipopolysaccharide Modulates Chemotactic Peptide-lnduced Actin Polymerization in Neutrophils
Authors: Howard Thomas H , Wang Danher , Berkow Roger L 
Published: January 2018

Abstract
To study the effect of endotoxin (LPS) on the basal and chemotactic peptide, formyl-methionyl-leucyl-phenylalanine (fMLP) -induced alterations in neutrophil cytoskeleton, we purified (&gt;98%) LPS-free neutrophils (LPS- &lt; 10 pg/ml LPS), compared their cytoskeletal organization to that of circulating neutrophils, and examined the effect of LPS exposure on the basal and fMLP-induced change in the cytoskeleton as reflected by F-actin content and distribution. Shape, F-actin content and distribution were monitored by FACS analysis and fluorescence microscopy of NBDphallicidin-stained cells. The F-actin content of basal and fMLP-activated, purified LPS- cells is similar to that of circulating neutrophils (defined as cells drawn in LPS- buffers at 37°C and analyzed after &lt;10 seconds of ex vivo manipulation). LPS- cells are round with a diffuse F-actin distribution. Exposure of LPS- cells to LPS causes cell polarization and F-actin redistribution without net gain in F-actin content. Peptide activation of the LPS- cell causes actin polymerization, which is preceded by a brief lag time. Exposure of LPS- cells to LPS (LPS+) enhances fMLP-induced actin polymerization by: 1) increasing the maximal extent of polymerization; 2) shortening the lag time preceding polymerization and increasing the rate of polymerization; and 3) lowering fMLP dose required for half maximal F-actin response. The enhancement depends on LPS dose, duration of exposure, and temperature. To examine the mechanism whereby LPS enhances fMLP-induced actin polymerization, we determined the predominant end for filament growth in LPS- and LPS+ cells, the number of actin nuclei generated in LPS- and LPS+ by fMLP activation, and the number and affinity of fMLP receptors on LPS- and LPS+ cells by 3[H]fMLP binding. Actin polymerization in both LPS- and LPS+ occurs predominantly by monomer addition to the barbed ends of nuclei, and the number of actin nuclei in basal and fMLP-activated LPS- and LPS+ cells is similar. LPS+ cells express three times more fMLP receptors than LPS- cells. The results show that LPS- cells are similar in cytoskeletal organization to circulating neutrophils, LPS causes shape change without change in F-actin content, and LPS enhances fMLP-induced actin polymerization response in neutrophils. The results suggest that LPS enhancement of actin polymerization response is associated with an increase in the number of fMLP receptors expressed on the cell surface.
Chemotactic Peptide Enhancement of Phorbol Ester-Induced Protein Kinase C Activity in Human Neutrophils
Authors: Gay James C , Stitt Ella S 
Published: January 2018

Abstract
Chemotactic factors and phorbol esters may act synergistically to evoke neutrophil responses, but the mechanism of such interaction is not entirely clear. We investigated the combined effects of the chemotactic peptide n-formyl-methionyl-leucyl-phenylalanine (FMLP) and phorbol myristate acetate (PMA) on protein kinase C (PKC) activity in human neutrophils. FMLP had little effect on the sharp decrease in cytosolic PKC activity induced by PMA. However, cells exposed to FMLP and PMA exhibited a synergistic increase in particulate PKC activity (1 ± 1 pmol 32P/107 PMNs/min in unstimulated cells, 53 ± 12 pmol 32P with 20 ng/ml PMA, 6 ± 3 pmol 32P with 10-7 M FMLP, and 191 ± 17 pmol 32P with FMLP and PMA). FMLP also markedly increased calcium/phospholipid-independent protein kinase activity in particulate fractions of control and PMA-treated cells. Enhancement of PKC activity required the presence of cytochalasin B during cell stimulation. Cellular calcium was crucial to the FMLP effect since enhancement was decreased in cells incubated with EGTA or Quin2. These results suggest that chemotactic factors and phorbol esters may mediate synergistic effects on neutrophil responses through enhancement of particulate PKC activity. The enhancing effect is probably mediated through chemoattractant-mediated increases in intracellular calcium.
Inhibition of Neutrophil and Eosinophil Chemotactic Responses to PAF by the PAF-Antagonists WEB-2086, L-652,731, and SRI-63441
Authors: Håkansson Lena , Venge Per 
Published: January 2018

Abstract
The influence of the three PAF-antagonists WEB-2086, L-652,731, and SRI-63441 on the chemotactic response of neutrophil and eosinophil granulocytes to PAF was investigated. When the PAF-antagonists were added to the cell suspension that was exposed to a gradient of PAF, WEB-2086 and SRI-63441 at the concentration of 10-6 mol/litre inhibited (P&lt;.01) the neutrophil and eosinophil chemotactic response to 10-8 and 10-9 mol PAF per litre; at the concentration of 5 x 10-6 mol/litre, WEB-2086 and SRI-63441 also inhibited (P&lt;.02) the response to 10-7 mol PAF per litre. Under the same conditions L-652,731 at the concentration of 5 x 10-6 mol/litre inhibited (P&lt;.01) the eosinophil chemotactic response to 10-8 and 10-9 mol PAF per litre. The inhibition of the chemotactic response to PAF by the three PAF-antagonists was specific, since the chemotactic response to C5f, f-MLP, and LTB4 was not affected by WEB-2086, L-652,731, or SRI-63441, neither was the chemokinetic migration induced by albumin.
“Autoregulation” of Human Neutrophil Activation In Vitro: Regulation of Phorbol Myristate Acetate-Induced Neutrophil Activation by Cell Density
Authors: Peters Stephen P , Cerasoli Franklin , Albertine Kurt H , Gee Marlys H , Berd David , Ishihara Yoko 
Published: January 2018

Abstract
Phorbol myristate acetate (PMA, 10-7 M) activation of adherent neutrophils (PMNs) led to a markedly attenuated release of superoxide anion (O2-) per cell when PMNs were activated at high density (2.85 fmol O2-/PMN at 2 million in 0.1 ml) in comparison with cells activated at low cell density (12.0 fmol O2-/PMN at 250,000 in 0.1 ml). This “autoregulatory” phenomenon was not due to a defect in the superoxide anion assay employed, to a differential adherence of neutrophils at high vs. low density, or to substrate (cytochrome c) or cell stimulus (PMA) limitation. It was associated with an inhibition of apparent NADPH oxidase activity and a leftward shift (toward a lower level of activation) in the activation profile of PMNs (as determined by FACS analysis using PMNs preloaded with 2′7′-dichlorofluorescin diacetate in which H2O2 production results in the production of the fluorescent product 2′7-dichlorofluorescein intracellularly). Other aspects of the neutrophil activation response including arachidonic acid mobilization, phospholipid metabolism, and perhaps phosphatidylinositol turnover were also attenuated when PMNs were activated at high cell density. Studies with cells in solution, cells treated with cycloheximide, and cells treated with 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid suggest that PMN contact with a surface, neutrophil protein synthesis, and an increased surface expression of the heterodimer CD11b/CD18 on PMNs all were not required for autoregulation. Finally, morphometric and morphologic examination of PMNs activated at low vs. high density revealed histologic and structural correlates associated with the attenuated PMN activation response of cells triggered at high cell density. We conclude that multiple structural and functional aspects of the PMN activation response are modulated by cell density and suggest that this property is important both in the physiologic control of neutrophil activation and in the design of in vitro assays of the neutrophil activation response.
Inhibition by AZT of HIV-1 Replication in Acutely Infected U-937 Cells
Authors: Boulerice François , Wainberg Mark A 
Published: January 2018

Abstract
We studied the effect of AZT on the replication of HIV-1 in freshly and chronically infected U-937 monocytoid cells over a period of 2 months. Expression of viral antigens was monitored by indirect immunofluorescence, and viral replication was assessed by reverse transcriptase assay on virus pelleted from culture fluids. In U-937 cells not treated by AZT, viral antigens were expressed by 7 days after infection. The inclusion of a variety of concentrations of AZT in the culture medium was shown to retard virus replication in a dose-dependent fashion, although a complete inhibitory effect was not seen with any clinically attainable concentration of drug. Exposure of HIV-1-inoculated cells to AZT did not give rise to progeny virus possessing a drug-resistant phenotype. However, the study of clonal derivatives of U-937 cells revealed cellular variants with increased susceptibility to HIV-1, and against which AZT had reduced effectiveness in comparison with the parental line. No effect of AZT was seen on cells already infected by HIV-1, suggesting that this drug had no influence on viral replication in U-937 cells into which viral DNA had previously integrated.
Purification and Characterization of Soluble Inositol 1,4,5-Trisphosphate 5-Phosphomonoesterase From Rabbit Peritoneal Neutrophils
Authors: Kennedy Scott P , Sha'afi Ramadan I , Becker Elmer L 
Published: January 2018

Abstract
A specific soluble inositol phosphate 5-phosphomonoesterase has been purified approximately 2,700-fold from a 120,000g supernatant of rabbit neutrophil homogenate. The specific enzyme represented 25–50% of the total hydrolytic activity toward inositol, 1,4,5-trisphosphate (lns-1,4,5-P3) with the remaining activity hydrolyzing both lns-1,4,5-P3 as well as inositol 1,4-bisphosphate (lns-1,4-P2). However, the enzyme could not be identified on sodium dodecyl sulfate-polyacrylamide gels stained with Coomassie blue, indicating that it represents a minor protein in the purified enzyme preparations. The purified enzyme has an apparent molecular mass of 43,000–47,000 daltons as determined by gel filtration and is free of other inositol phosphate phosphomonoesterases. The enzyme hydrolyzes lns-1,4,5-P3 with an apparent Km of 18 μM and a Vmax of 1.2 μmol/min/mg. The 5-phosphomonoesterase requires Mg2+ for activity and is not affected by physiological concentrations of Ca2+ or calmodulin. The pH optimum for activity is 7.5. Inositol 1,3,4,5-tetrakisphosphate is a potent competitive inhibitor of lns-1,4,5-P3 hydrolysis (Ki = μM), whereas lns-1,4-P2 is a weak inhibitor (Ki = 173 μM). lns-1,4,5-P3 hydrolysis is relatively unaffected by monophosphorylated substrates, however, bisphosphorylated substrates are potent inhibitors. Comparisons of neutrophil 5-phosphomonoesterase characteristics with those of platelet and rat brain enzymes support the idea that each 5-phosphomonoesterase may be a unique enzyme and play a different role dependent upon the cell or tissue in which it acts.
Human Recombinant Interleukin-2 Induces Maturation and Activation Signals for Feline Eosinophils In Vivo
Authors: Tompkins Mary B , Novotney Carol , Grindem Carol B , Page Rodney , English Robert , Nelson Philip , Tompkins Wayne A F 
Published: January 2018

Abstract
Immunotherapy, with interleukin-2 (IL-2) or IL-2 plus lymphokine-activated killer (LAK) cells, has been used to treat cancer and acquired immunodeficiency syndrome (AIDS) in man. Similarities between feline leukemia virus (FeLV) infection in the cat and human immunodeficiency virus (HIV) infection in man have prompted immunotherapeutic studies in the cat. To develop baseline data on hematological responses to infused IL-2, cats were given daily (1–14 days) i.v. injections of 5 × 104 U/kg of recombinant human IL-2 (rHulL-2). Complete blood cell (CBC) counts were done weekly. Red blood cell (RBC), neutrophil, and lymphocyte numbers did not change appreciably over the course of the study. In contrast, rHulL-2 caused an eosinophilia in all but the 1 day treatment group. Treatment for 3 days generated a transient eosinophilia on day 7 that returned to baseline by 3 weeks. Five day and 7 day treatments generated an eosinophilia by day 7 that peaked on day 14 and returned to normal values by day 28. Treatment of cats for 14 days did not increase the magnitude or duration of the eosinophilia beyond the 5 or 7 day treatments. Bone marrow (BM) biopsies from rHulL-2-treated cats revealed a marked selective hyperplasia of eosinophil precursors. In the 5 day treatment group, all maturation stages of eosinophils were elevated by week 1 of treatment. By week 2, the early stages had returned to normal, whereas the late stage cells remained elevated, suggesting an ordered maturation response. Numbers of all eosinophil precursors approximated pretreatment numbers by weeks 3–4. Thus the BM hyperplasia preceded the blood eosinophilia by 1 week, suggesting that an enhanced maturation response of BM eosinophil precursors is a major contributor to the rHulL-2-induced blood eosinophilia. In addition to a maturation signal, rHulL-2 induces a potent activation signal for eosinophils as measured by a decrease in density and an increase in longevity in culture. The significance of the activated eosinophil in the therapeutic or toxicologic response to rHulL-2 infusion is discussed.
Sources of Antibody-Dependent Cellular Cytotoxicity Deficiency in Young Pig Leukocytes
Authors: El-Awar Faisal Y , Hahn Edwin C 
Published: January 2018

Abstract
Antibody-dependent cellular cytotoxicity (ADCC) activity against pseudorabies virus-infected target cells has been found to be lower in young pig peripheral blood leukocytes (PBLs) than in adults. Experiments were designed to investigate the reason(s) for low activity in the young, which are more at risk of fatal infection than adults. The percentage of polymorphonuclear leukocytes (PMNs), the major ADCC effector cell, in the whole leukocyte population did not have a bearing on the deficiency. Enrichment for PMNs did not alleviate differences in activity between young and adult pigs. Additionally, no suppressor cell(s) or factor(s) could be demonstrated to account for the ADCC deficiency. The source of the ADCC deficiency in the young was found to be related to the decreased ability of young pig effector cells to bind antibody-sensitized targets. This deficiency relative to adults was associated with decreased antibody binding to high affinity Fc receptors on young pig neutrophils.