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Biomedical subjects

L A Boxer

Publications and source records attributed to L A Boxer.

At least 145 records · Page 8Linked to original sources
PubMed1982

Correlation of in vitro and in vivo effects of gold compounds on leukocyte function: possible mechanisms of action.

The anti-inflammatory effects of gold compounds include suppression of PMN lysosomal enzyme release. Since lysosomal products can provoke PMN aggregation, we assessed the effect of two gold compounds, auranofin and GST, on suppressing aggregation, degranulation, and metabolic functions of the cells. Aggregation of 1 x 10(7) cytochalasin B-treated PMNs in response to 2 x 10(-7)M FMLP, as assessed by light scattering, was inhibited in a dose-dependent fashion by both drugs. Concentrations of auranofin ranging from 5 to 20 microM caused 30.8% to 89% inhibition, whereas 200 microM GST reduced aggregation by only 32%. FCS or BSA added to suspensions of normal PMNs considerably reduced the gold compound inhibitory effect on PMN aggregation. Cell viability assessed by dye exclusion and lactate dehydrogenase release was unaffected by the drugs. The suppressive activities of the drugs could not be removed by washing the PMNs. Correspondingly, the drugs suppressed lysosomal enzyme release induced by FMLP of PMNs rendered secretory with cytochalasin B. Concentrations of 20 microM auranofin and 200 microM GST resulted, respectively, in a 61.5% and 19.3% reduction of release of lysozyme, 61.7% and 27.1% reduction of beta-glucuronidase, 84.8% and 33.7%s reduction of myeloperoxidase, and 50.0% and 25.0% reduction of lactoferrin. Furthermore, auranofin inhibited 14C-1-glucose oxidation through the hexose monophosphate shunt in response to stimulation by either PMA or methylene blue. The in vivo studies suggested that auranofin could prevent neither neutropenia induced by zymosan-activated serum nor a corresponding rise in plasma lactoferrin levels. These findings suggest that the beneficial effect of gold compounds in rheumatoid arthritis are unlikely to be related to their ability to dampen PMN activation in vivo.

Animals↗
PubMed1982

Mechanism of dexamethasone inhibition of chemotactic factor induced granulocyte aggregation.

The reaction of FMLP with granulocytes causes aggregation and degranulation and enhances adherence to endothelium. To evaluate whether prevention of granule extrusion could impair these granulocyte activities, granulocytes were treated with either dexamethasone or hydrocortisone prior to treatment with FMLP. Dexamethasone was added to suspensions of cytochalasin B-treated granulocytes; it markedly impaired the aggregation response of the granulocytes of FMLP. When cytochalasin-B was not used, granulocyte aggregation in response to FMLP or PMA was inhibited by dexamethasone. Although dexamethasone prevented aggregation of cells following stimulation with FMLP or PMA, it failed to prevent the aggregation of granulocytes induced by rabbit lactoferrin. Adherence of granulocytes to human endothelial monolayers was enhanced by FMLP; dexamethasone inhibited the enhancement. However, with the addition of human lactoferrin to the granulocytes exposed to dexamethasone, the cells were able to adhere as well to endothelium as the cells exposed to FMLP but free of dexamethasone. When cytochalasin-B-treated granulocytes were incubated with dexamethasone or hydrocortisone prior to the addition of FMLP, the subsequent release of lactoferrin was substantially blocked, whereas the release of the primary granule products, lysozyme and beta-glucuronidase, was attenuated but not completely blocked. Thus, corticosteroids might block chemotactic-factor-induced granulocyte aggregation by selectively preventing release of specific granule products that contribute to and sustain aggregation.

Cell Aggregation↗
PubMed1982

Neutropenia induced by systemic infusion of lactoferrin.

Rabbit granulocyte lactoferrin, when infused into hamsters or rabbits, induces transient neutropenia, and in hamsters the lactoferrin promotes adherence of the granulocytes to the endothelial cell wall as monitored visually. In contrast, neither rabbit granule lysozyme nor human transferrin induces neutropenia in the rabbit nor does transferrin or bovine serum albumin affect the adherent properties in vivo of the phagocytic cells of the hamster. Thus lactoferrin enhances granulocyte adherence both in vivo and in vitro. It would appear that the promotion of margination of leukocytes by lactoferrin in vivo may contribute to the phenomenon of neutropenia during activation of granulocytes by chemotactic factors.

Agranulocytosis↗
PubMed1982

Enrichment by counterpart centrifugal elutriation of human lymphocytes cytotoxic to human tumour cells.

The enriched fractions of cytotoxic cells responsible for natural killer (NK) activity against both human sarcoma and neuroblastoma (LA-N2) cell lines were readily obtained by countercurrent centrifugal elutriation (CCE). The NK cells were obtained in the larger lymphocyte fractions (fraction 6 +/- 1), having a mean cell volume of 180 u3. The cytotoxic-enriched fraction contained 51% large lymphocytes having cytoplasmic granules. On the other hand, monocytes were purified to greater than 90% and isolated in another fraction (final fraction) and these cells had the lowest NK activity against both human tumour cell lines. However, compared with the lymphocyte fractions, small and large monocytes displayed greater antibody-dependent cellular cytotoxicity (ADCC) activity against human B erythrocytes. These results indicate that NK found to have activity against both tumour cells lines were larger lymphocytes, not small monocytes. Thus, countercurrent centrifugal elutriation (CCE) can provide a sensitive method to obtain enriched fractions of large lymphocytes contained tumoricidal activity against human sarcoma and neuroblastoma cell lines.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1982

Ultrastructural localization of lactoferrin and iron-binding protein in human neutrophils and rabbit heterophils.

Lactoferrin in marrow and blood granulocytes from rabbits and humans was stained with an immunoferritin method. Iron-binding protein(s) was localized by the staining of granulocytes with acid ferrocyanide after saturation of the iron-binding protein with iron. The latter was most readily accomplished by treatment of the glutaraldehyde-fixed cell suspension with 1% saponin, followed by treatment with an iron-nitrilotriacetate (Fe-NTA 3mM:4mM) solution, adjusted to pH 7.0 with NaHCO3. The affinity of purified lactoferrin and transferrin for radioiron after such treatment was minimally diminished. Both immunoferritin and iron-binding methods heavily stained osmiophiliuc (phospholipid-containing) mature primary granules in late promyelocytes, myelocytes, and polymorphonuclear cells. Early promyelocytes containing abundant immature primary granules lacked immunoferritin or iron staining. Trypsin digestion of rabbit marrow cells considerably diminished the cytochemically demonstrable iron-binding capability of the mature primary granules. Specimens sequentially stained for peroxidase and immunostained for lactoferrin or cytochemically stained for iron-binding protein confirmed that lactoferrin and iron-binding protein were in peroxidase-positive primary granules. Some peroxidase positive granules appeared to lack staining for lactoferrin and iron-binding proteining protein, and all secondary granules uniformly lacked staining. Treatment of human neutrophils with phorbol myristate acetate demonstrated early release of granules containing iron-binding protein with subsequent agglutination of neutrophils and attachment of iron-binding protein to the cell surface. In summary, this study distinguishes at least two subpopulations of primary granules and identifies lactoferrin and an iron-binding protein(s) in a subpopulation of peroxidase-positive primary granules in rabbit heterophils and human neutrophils.

Animals↗
PubMed1981

Phagocytosis of neutrophils by marrow macrophages in childhood chronic benign neutropenia.

Chronic benign neutropenia of childhood is a heterogeneous disorder. This study describes two severely neutropenic children with a benign clinical course and the unique bone marrow finding of macrophage engulfment of band and segmented neutrophils. Phagocytic vacuoles in the majority of macrophages contained neutrophils in various stages of digestion at both the light and electron microscope level (with as many as four neutrophils observed in single macrophages). Ultrastructural studies demonstrated that the neutrophils were morphologically normal, and apparently viable at the time of phagocytosis. This type of neutrophil phagocytosis was not observed in five other consecutively studied children with CBN. All of these children with CBN had ultrastructurally normal neutrophils, lacked demonstrable antineutrophil antibodies or serum inhibitors to in vitro myelopoiesis, and had normal colony-forming cells and colony-stimulating activity in vitro. Thus despite many similar clinical and laboratory features in children with CBN, only a unique subgroup of these patients demonstrates abnormal neutrophil-macrophage interaction.

Adolescent↗
PubMed1981

Fluidity properties and liquid composition of erythrocyte membranes in Chediak-Higashi syndrome.

We have earlier shown through electron spin resonance (ESR) studies of leukocytes that membranes of cells from both Chediak-Higashi syndrome (CHS) mice and humans have abnormally high fluidity. We have extended our studied to erythrocytes. Erythrocytes were labeled with the nitroxide-substituted analogue of stearic acid, 2-(3-carboxypropyl)-4,4-dimethyl-2-tridecyl-3-oxazolidinyloxyl, and ESR spectra were obtained. Order parameter, S, at 23 degrees C, was 0.661 and 0.653 for erythrocytes of normal and CHS mice (P less than 0.001). S was 0.684 for normal human erythrocytes and 0.675 (P less than 0.001) for CHS erythrocytes at 25 degrees C. Because S varies inversely to fluidity, these results indicate that CHS erythrocytes tend to have higher fluidity than normal. In vitro treatment of both mice and human CHS erythrocytes with 10 mM ascorbate returned their membrane fluidity to normal. We prepared erythrocyte ghosts and extracted them with CHCl3:CH3OH (2:1). Gas-liquid chromatography analysis showed a greater number of unsaturated fatty acids for CHS. The average number of double bonds detected in fatty acids for mice on a standard diet was 1.77 for normal and 2.02 for CHS (P less than 0.04); comparison of human erythrocytes from one normal control and one CHS patient showed a similar trend. Our results suggest that an increased proportion of unsaturated fatty acids may contribute to increased fluidity of CHS erythrocytes. Our observation that both leukocytes and erythrocytes of CHS have abnormal fluidity indicates that CHS pathophysiology may relate to a general membrane disorder.

Animals↗
PubMed1981

Changes in energy metabolism, structure and function in alveolar macrophages under anaerobic conditions.

To determine whether the change in energy metabolism of guinea-pig alveolar macrophages (AM) would alter their function to resemble peritoneal macrophages (PM), AM were exposed to strict anaerobic environments for 96 h. Exposure of cultivated AM to hypoxic conditions resulted in a decreased activity of cytochrome oxidase, a key enzyme in oxidative phosphorylation, whereas pyruvate kinase activity, a key enzyme in glycolysis, increased to levels observed in PM. Under hypoxic conditions the total mitochondrial structure available for respiratory activity also decreased in the glycolytic energy-dependent AM. Accompanying the shift in energy metabolism, adaptive changes in the functional responses of lectin-receptor activity occurred in the AM exposed to hypoxic conditions. Culture of AM in an anaerobic environment led to a loss in their ability to mobilize their lectin receptors in response to cytochalasin B, whereas AM maintained in an aerobic environment could mobilize their receptors in response to either cytochalasin B and D. Alterations in O2 tension affect AM metabolism, morphology and function and indicate that the AM is able to change its energy metabolism according to environmental circumstances.

Anaerobiosis↗
PubMed1981

Rabbit cationic protein enhances leukocyte adhesiveness.

Cationic protein purified from rabbit peritoneal polymorphonuclear leukocytes (PMN) was demonstrated to incite autoaggregation of the rabbit PMN and promote adhesiveness of human PMN to endothelial cells. PMN aggregation induced by supernatants derived from secretory PMN was blocked by a specific anticationic protein antibody. These studies reveal that a positively charged protein derived from the PMN can alter surface properties of the PMN itself and imply a role for this protein in PMN immobilization at inflammatory sites.

Animals↗
PubMed1981

Molecular analysis of the beta-thalassemia phenotype associated with inheritance of hemoglobin E (alpha 2 beta2(26)Glu leads to Lys).

Inheritance of the gene for betaE-globin is associated with hypochromia and microcytosis, reminiscent of typical heterozygous beta-thalassemia. Patients with hemoglobin (Hb)E-beta-thalassemia exhibit clinical phenotypes of severe beta-thalassemia, a circumstance not encountered in other compound heterozygous states for structural beta-chain mutations and beta-thalassemia. We have analyzed the kinetics of globin synthesis and the levels of globin messenger (m) RNA accumulation in patients with Hb E-beta-thalassemia and Hb E trait. The initial rate of beta-globin synthesis (betaE/alpha=0.20-0.34) was less than expected on the basis of gene dosage, or comparable studies of other compound heterozygous states for beta-thalassemia and structurally abnormal beta-chains. betaE-globin synthesis was not only reduced during short-term incubations (1-5 min), but also remained relatively unchanged during long-term pulse or chase incubations up to 5h. Analysis of globin mRNA by cell-free translation and molecular hybridization confirmed that the unexpectedly low levels of betaE-globin synthesis were associated with comparable reduction in the levels of beta-globin mRNA. In Hb E-beta-thalassemia the betaA + betaE (alpha globin nRNA ratio observed were substantially lower than those obtained from reticulocytes of patients with heterozygous beta-thalassemia, or Hb S-betaO-thalassemia, while in Hb E trait, the betaA + betaE/alpha mRNA ratio was in the ranged observed for beta-thalassemia trait. The betaE-globin gene specifies reduced accumulation of betaE-globin mRNA, a property characteristic of other forms of beta-thalassemia. The beta-thalassemia phenotype associated with inheritance of Hb E is thus determined at the level of beta-globin mRNA metabolism.

Globins↗
PubMed1981

Purification of myosin light chain kinase from rabbit polymorphonuclear leukocytes.

To investigate the regulation of actin-myosin interaction in rabbit phagocytic cells, purified myosin and a partially purified cofactor protein were obtained from polymorphonuclear leukocytes (PMN) and alveolar macrophages (ALM) by molecular sieve filtration over an agarose column. ALM cofactor enhanced the Mg++-ATPase activity of ALM myosin by actin to 0.15 +/- 0.04 mumoles Pi per mg myosin per min and PMN cofactor enhanced PMN myosin to 0.43 +/- 0.03 mumoles Pi per mg myosin per min. The crude cofactor preparations isolated from the two types of leukocyte extracts were interchangeable with the leukocyte myosins. When ALM cofactor was added to a PMN actomyosin complex, the Mg++-ATPase activity of the PMN myosin was 3-fold higher than with ALM cofactor and its own actomyosin complex. In contrast, PMN cofactor did not enhance ALM actomyosin Mg++-ATPase activity beyond that observed with ALM cofactor and ALM actomyosin. Cofactor protein from the PMN was further purified on a DEAE-Sephagel column. After electrophoresis on sodium dodecyl sulfate-polyacrylamide gel, the isolated fraction weighed 70,000 daltons. This fraction stimulated the actinmediated myosin Mg++-ATPase. In the presence of Mg++ and [gamma 32P]ATP, the 70,000 dalton protein phosphorylated the 20,000 dalton light chain of PMN myosin, leading to the incorporation of 0.62 +/- 0.09 moles of Pi per mole myosin. On the basis of these results, we propose that phagocytic cofactor is a kinase which regulates the enzymatic activity of phagocytic cell myosin.

Actomyosin↗
PubMed1981

Accumulation of circulating macrophages in lungs of guinea pigs exposed to hyperoxia.

Superoxide dismutase (SOD) and glutathione peroxidase (GPx) key enzymes in alveolar macrophages regulating levels of superoxide anion and hydrogen peroxide, respectively, were observed to fluctuate in response to FIO2 of 50 and 85% for 18 to 90 hr. At the lower oxygen tension, SOD rose two-fold and GPx decreased significantly by 18 hr and throughout the exposure periods compared to a delayed increase in SOD activity which was not sustained beyond 66 hr of exposure and a sustained rise in GPx to an FIO2 of 85%. Peritoneal macrophages containing lower SOD activity and greater GPx activity than resident alveolar macrophages upon injection into the circulation resulted in 10-fold accumulation in the lungs during exposure of animals to FIO2 of 85% but not at 50%. This study indicates that brief exposure to FIO2 of 85% but not 50% resulted in alterations of the vascular integrity of the lungs resulting in the accumulation of circulating macrophages to the alveolar macrophage pool. The delayed rise in SOD activity and the sustained increase in GPx activity in alveolar macrophages from animals exposed to FIO2 of 85% could in part be related to this influx of circulating macrophages with enzymatic characteristics observed for peritoneal macrophages.

Animals↗
PubMed1981

Functions of human monocyte and lymphocyte subsets obtained by countercurrent centrifugal elutriation: differing functional capacities of human monocyte subsets.

Two monocyte subsets from the peripheral blood of healthy humans were isolated by countercurrent centrifugal elutriation (CCE), and their functional heterogeneity was assessed. Cell volume of the smaller monocyte population was (332 +/- 32 mu 3), compared with the larger monocytes (380 +/- 30 mu 3). Superoxide release by large monocytes exposed to opsonized zymosan was 1.5-fold more active than those of small monocytes. Furthermore, the production of colony-stimulating factor (CSF) and myeloperoxidase activity by the larger monocytes was 2-fold and 1.4-fold greater than that of small monocytes, respectively. Thus, CCE provides a useful means to isolate 2 subsets of monocytes with similar functional properties but quantitatively different activities. This suggests that the 2 subsets may be closely related in their developmental spectrum.

Bone Marrow Cells↗
PubMed1981

Amphotericin-B promotes leukocyte aggregation of nylon-wool-fiber-treated polymorphonuclear leukocytes.

Severe pulmonary reactions have been reported in patients receiving leukocyte transfusion and amphotericin-B. To study the interaction of amphotericin-B with polymorphonuclear leukocytes (PMN), purified human PMN were incubated with 200 mg of nylon wool fiber for 60 min either in the absence or presence of 2 mM EDTA. PMN were recovered in acid citrate dextrose solution and were suspended in balanced salt solution for determination of their aggregation properties. The cells exposed to nylon wool fibers without EDTA aggregated in response to concentration as low as 1.25 micrograms/ml of amphotericin-B. Cells initially treated with EDTA, however, failed to aggregate. Serum from a patient treated with amphotericin-B aggregated PMN exposed to nylon wool fiber but not control cells, whereas serum taken before amphotericin was given without effect on the PMN treated with nylon wool fiber. Amphotericin-B at 5 micrograms/ml failed to potentiate the release of beta-glucocuronidase or lactic dehydrogenase by PMN treated by nylon wool beyond that seen with exposure to the fibers alone. Rabbit peripheral blood was similarly incubated with nylon wool fibers and the recovered PMN were infused into recipient rabbits that had received 1 mg/kg of amphotericin-B intravenously 1 hr prior to the infusion of the leukocytes. Rabbits were sacrificed 30 min after transfusion of PMN, and their lungs were excised for histologic sectioning. Those rabbits receiving a combination of amphotericin-B and 4 x 10(7) nylon-wool-fiber-treated PMN had evidence of pulmonary hemorrhage and accumulation of leukocytes in the pulmonary vasculature whereas those animals who received such cells alone had normal appearing lung tissue. In summary, amphotericin-B at concentrations achievable in vivo enhanced the aggregation of PMN damaged by incubation with nylon fiber with subsequent accumulation of the phagocytes in pulmonary tissue.

Amphotericin B↗
PubMed1981

Lactoferrin: a promoter of polymorphonuclear leukocyte adhesiveness.

Polymorphonuclear leukocytes (PMN) degranulate, adhere to vascular endothelium, or aggregate to each other following exposure of the cells to high concentrations of chemotactic stimuli such as formyl-methionyl-leucyl phenylalanine (FMLP). PMN released the specific granule product lactoferrin more readily in response to chemotactic stimuli, which correlated with promotion of PMN aggregation as measured by light transmission and enhanced PMN adherence. Both concanavalin A (Con-A) and phorbol myristate acetate (PMA), agents that lead to specific granule discharge, induced and sustained human PMN aggregation. Similarly, supernatants, generated from Con-A-treated PMN, aggregated fresh PMN in the presence of alpha-methylmannoside, a competitive inhibitor of the lectin. Anti-human lactoferrin IgG but not normal goat IgG blunted the aggregation elicited by both PMA and FMLP. Both human milk lactoferrin and rabbit PMN lactoferrin aggregated human lactoferrin promoted PMN adherence to endothelial cells. The enhanced PMN stickiness was correlated with the early phase of degranulation. Thus, PMN lactoferrin serves an autoregulatory role to retain PMN at inflammatory sites to amplify the inflammatory response.

Animals↗
PubMed1981

Immune neutropenias. Clinical and biological implications.

Techniques for the detection of neutrophil antibodies include leukoagglutination, cytotoxic assays, antiglobulin consumption tests, immunofluorescence, quantitation of cell-bound IgG, and opsonization assays. Employment of the various methodologies have led to the identification of neutropenic states associated with decreased survival of neutrophils in the circulation because of immune-mediated distribution of the neutrophils or excessive sequestration of their cells by reticuloendothelial cells. The immune clinical syndromes predisposing to selective neutropenia include isoimmune neonatal neutropenia, autoimmune neutropenia, drug-induced neutropenia, and complement-mediated neutropenia. Selective immune-mediated neutropenia occurs because the neutrophil contains unique antigens often not shared by other blood cells. Like incompatible red cell transfusions, incompatible neutrophil transfusions can result in clinical manifestations including fever and hypoxemia arising from pulmonary sequestration of neutrophils. Potentially therapeutic benefits derived from neutrophil transfusions and from bone marrow transplantations may be influenced by neutrophil antigen-antibody reactions. Newer techniques for detecting and identifying neutrophil antibodies may now provide a tool to answer these questions.

Adolescent↗