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R Seljelid

Publications and source records attributed to R Seljelid.

At least 19 recordsLinked to original sources
PubMed1992

Inactivation of thrombin by murine peritoneal macrophages.

We recently showed that murine peritoneal macrophages cultured in vitro express potent prothrombinase activity (Lindahl, U., Pejler, G., Bøgwald, J., and Seljelid, R. (1989) Arch. Biochem. Biophys. 273, 180-188). In the present report, we demonstrate that the macrophages also express anticoagulant activity by inactivating the thrombin that is formed due to the action of the prothrombinase. Addition of exogenous purified thrombin to the macrophage cultures resulted in inactivation of the enzyme at a maximum rate of approximately 5 micrograms/h/10(6) cells. The inactivation appeared to be specific for thrombin, since neither Factor Xa, chymotrypsin, nor trypsin, three serine proteases exhibiting homology with thrombin, were inactivated by the macrophages. Thrombin-inactivating activity was not secreted into the culture medium. Inhibitors of endocytosis did not decrease the rate by which thrombin was inactivated, suggesting that internalization of the coagulation factor was not required. In contrast, the thrombin-inactivating activity was strongly inhibited by the polycation Polybrene. Anion-exchange chromatography of extracts obtained after Triton X-100-solubilization of the macrophages demonstrated that the thrombin-inactivating activity exhibited a high negative charge. Incubation of the thrombin-inactivating activity recovered after anion-exchange chromatography with unlabeled thrombin, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, showed that thrombin was proteolytically cleaved into defined fragments. Similar proteolytic fragments were obtained when 125I-labeled thrombin was added to macrophage cultures. Degradation of thrombin was blocked by phenylmethanesulfonic fluoride, an inhibitor of serine proteases, but not by inhibitors of other classes of proteases. Thrombin that had been chemically modified at its active site was degraded at the same rate by the macrophages as active thrombin. Taken together, these findings indicate that the murine macrophages express surface-bound serine protease activity that specifically inactivates thrombin by proteolytic cleavage. The significance of thrombin-inactivating activity in relation to the involvement of macrophage procoagulant activity in the immune response is discussed.

Animals↗
PubMed1992

Killing of Escherichia coli by mononuclear phagocytes and neutrophils stimulated in vitro with beta-1,3-D-polyglucose derivatives.

Human monocytes, human peritoneal macrophages, mouse peritoneal macrophages and human peripheral neutrophils pretreated with beta-1,3-D-polyglucose derivatives showed pronounced bactericidal capacity to Escherichia coli compared to control cells. The increased bactericidal capacity was detectable in mononuclear phagocytes over a wide range of concentrations of bacteria. Granulocytes, however, showed bactericidal capacity only at low concentrations of bacteria. The pretreated mononuclear phagocytes released significant amounts of IL-1 and PGE2. However, there was no significant release of tumor necrosis factor (TNF). By incubating unstimulated cells with purified IL-1 and TNF, the bactericidal activity of neutrophils and mononuclear phagocytes was enhanced. Our data indicate that the inability of neutrophils stimulated with beta-1,3-D-polyglucose derivatives to kill large numbers of bacteria could be overcome by a combined treatment with purified IL-1 or TNF in addition to beta-1,3-D-polyglucose derivatives. By incubating unstimulated cells with medium from beta-1,3-D-polyglucose-treated human peritoneal macrophages, the bactericidal activity of the cells was enhanced to the same extent as cells pretreated with purified TNF and IL-1. Cells incubated with IL-1-depleted medium from beta-1,3-D-polyglucose-treated human peritoneal macrophages, showed reduced bactericidal activity compared to cells incubated with undepleted medium. These studies demonstrate that beta-1,3-D-polyglucose-treated mononuclear phagocytes and neutrophils show enhanced bactericidal activity. The enhanced activity is partly caused by stimulation of the cells with IL-1 released from mononuclear phagocytes and partly by other unknown effects of beta-1,3-D-polyglucose derivatives on both mononuclear phagocytes and neutrophils.

Animals↗
PubMed1992

Effects of stress on the growth of a fibrosarcoma in nu/nu and conventional mice.

BALB/c mice subjected to water stress twice daily, between 3 and 7 min at each exposure 3 days before, 5 days after, or 3 days before and 5 days after intradermal Meth A tumour transplantation, showed an increase of tumour size and tumour growth rate compared with that of home cage control (HCC) mice. However, BALB/c mice subjected to water stress 3 days before and 6 days after tumour transplantation showed a decrease of tumour size and tumour growth rate compared with HCC mice. BALB/c mice subjected to 2 min of handling stress daily on days 1 through 5, but not BALB/c mice subjected to handling stress on days 1 through 7 or on days 6 through 7 of tumour growth, showed an increased in tumour size relative to HCC mice. On the other hand, BALB/cBy mice handling stressed on days 1 through 7, but not BALB/cBy mice handling stressed on days 1 through 5 or days 6 through 7 after tumour transplantation, showed a decreased tumour size compared with HCC mice. No effect of stress could be observed when nu/nu BALB/c mice were subjected to water stress 3 days before and 6 days after tumour transplantation. However, BALB/c nu/nu mice pre-injected intraperitoneally with spleen cells from conventional mice had a decreased tumour size and growth rate of the tumour when stressed 3 days before and 6 days after tumour transplantation.

Animals↗
PubMed1992

Quantification of neutral red pinocytosis by small numbers of adherent cells: comparative studies.

A colorimetric assay has been developed for studies on neutral red (NR) pinocytosis by small numbers (below 2 x 10(5)) of adherent cells cultured in 96 well plates. The NR uptake per cell mass was much higher in the sea urchin perivisceral adherent cells and human HL-60 cell line monolayers than in the murine and Atlantic salmon macrophages. The apparent difference points to the usefulness of this novel assay in comparative studies.

Animals↗
PubMed1991

Novel immunomodulators with pronounced in vivo effects caused by stimulation of cytokine release.

Beta-1,3-D-polyglucose derivatives protect mice against otherwise lethal bacterial infections. This protective effect has been considered to be mediated through mononuclear phagocytes. By using radioactive labelling, we localized the beta-1,3-D-polyglucose derivatized microbeads (GDM) during the period following injection. The GDM was recovered mainly in the milky spots of the omentum. In animals treated with GDM, the total white cell number was significantly increased in peritoneal fluid of mice before and after challenge with E. coli. Bacterial counts in peritoneal fluid of GDM treated animals declined to zero after 24 h. In untreated animals there was a slight increase in bacterial counts until the animals died after about 12 h. Mouse peritoneal macrophages stimulated with GDM released significant amounts of IL-1 and PGE2. There was no significant release of TNF. Levels of IL-1 and PGE2 in peritoneal fluid increased significantly during the first 48 h after treatment with GDM. There was no increase of levels of TNF. After challenge with E. coli, the levels of IL-1, TNF, and PGE2 were significantly lower compared with control animals. In untreated animals the levels of IL-1 and TNF remained elevated until the animals died after about 12 h. These studies demonstrate that the raised levels of arachidonic acid metabolites after pretreatment with GDM or AG seems to inhibit the otherwise lethal elevation of IL-1 and TNF in body fluids which is seen in untreated animals.

Adjuvants, Immunologic↗
PubMed1991

Effect of soluble aminated beta-1,3-D-polyglucose on human monocytes: stimulation of cytokine and prostaglandin E2 production but not antigen-presenting function.

Glucans are insoluble polymers of beta-1,3-linked glucose derived from yeast cell walls that effectively activate macrophages. Recently, aminated derivatives of beta-1,3-D-polyglucose have been developed that are soluble but also activate murine macrophages. The current studies were undertaken to determine whether soluble aminated beta-1,3-D-polyglucose (AG) would also stimulate human monocytes. The AG employed contained less than 2 ng endotoxin/mg. AG induced the production of intracellular, membrane-associated, and secreted forms of interleukin 1 (IL1) in a dose-dependent manner, with 50 micrograms/ml yielding maximal responses. AG also induced tumor necrosis factor-alpha (TNF alpha) secretion by human monocytes. Prostaglandin E2 (PGE2) production was also stimulated in a concentration-dependent manner. Quantitatively, optimal stimulatory concentrations of AG were comparable to endotoxin in the capacity to induce production of these various mediators. In contrast to its capacity to induce production of IL1, TNF alpha, and PGE2, AG did not stimulate monocytes to become more effective antigen presenting cells. These results indicate that AG is potent inducer of proinflammatory mediators from human monocytes but does not enhance their capacity to initiate immune responses.

Cells, Cultured↗
PubMed1991

Phagocytosis of beta-1,3-D-glucan-derivatized microbeads by mouse peritoneal macrophages involves three different receptors.

Intraperitoneal injection of beta-1,3-D-glucan coupled to the surface of monodisperse methacrylate microbeads improves the resistance against bacterial infections in mice, while methacrylate microbeads alone do not. The effect of the glucan-derivatized microbeads (GDM) is considered to be mediated through peritoneal macrophages. We show that both GDM and the underivatized methacrylate microbeads (UDM) treated with normal serum were rapidly bound and phagocytized by mouse peritoneal macrophages in vitro. We found that both complement and fibronectin opsonized the beads and were responsible for the uptake. Treatment of microbeads with serum lacking fibronectin and complement activity still gave some uptake of GDM, but not uptake of UDM. The uptake of GDM was similar to the uptake of untreated GDM and was inhibited by pretreatment of macrophages with soluble beta-1,3-D-glucan. Our conclusion is that GDM and UDM intraperitoneally bind fibronectin and C3 through activation of the alternative pathway of complement. This leads to their phagocytosis by macrophages through fibronectin and complement receptors. GDM are also internalized via beta-glucan receptors. We present the hypothesis that the beta-glucan receptors on peritoneal macrophages account for the protective effect of GDM in intraperitoneal bacterial infections.

Animals↗
PubMed1991

The effect of various contexts of stress on the mouse spleen lymphocytes and macrophage co-stimulatory activity.

Mice stressed daily by brief cold water immersions for 1, 8 or 14 days showed changes in immune system function which were dependent on the number of mice per cage, frequency of stress exposures and total number of stress exposures. Changed percentages of spleen B and CD4, but not of CD8 cells were determined when the mice were stressed either once or twice daily. With CD4 cells, increased percentages were seen after stress once daily but a decreased percentage was seen after stress twice daily. Furthermore, the Concanavalin A-stimulated spleen cell mitogenesis was decreased after 1 day of stress in mice stressed once daily as opposed to after 8 and 14 days of stress in mice stressed twice daily. After 14 days of stress, the lipopolysaccharide stimulated mitogenesis was increased if the mice were stressed once daily but decreased if the mice were stressed twice daily. With two mice per cage, we observed a decreased spleen cell mitogenesis after 14 days of stress. With four mice per cage, the spleen cell mitogenesis was decreased after 8 and 14 days of stress. If spleen cell populations from mice stressed twice daily for 8 days were depleted of macrophages and CD4 or CD8 cells, the effect of stress on the mitogenesis was removed from the CD8 cells. Spleen cells of mice stressed for 14 days showed a decreased mitogenesis when depleted of adherent cells and reconstituted with adherent cells from control mice. Furthermore, the adherent cells from these mice had decreased ability to support mitogenesis of adherent cell-depleted spleen cells from control mice as well as a decreased IL-1 production.

Animals↗
PubMed1991

The effect of stress in vivo on the function of mouse macrophages in vitro.

Macrophages were harvested from home cage control (HCC) mice, and from mice which had been stressed by repeated brief exposures (3-8 min) to cold water at 10-15 degrees C twice daily for 8 or 14 days. Macrophages obtained from mice stressed 8 or 14 days compared to macrophages from HCC mice showed in vitro increased amounts of membrane-bound prothrombinase activity, whereas the thrombin degradation activity was unchanged. Furthermore, macrophages of mice stressed 8 days showed increased release of coagulation factor X/Xa to supernatant in vitro. These findings suggest an increased amount of prothrombinase complex enzymes on the surface of macrophages from mice stressed 8 days, and increased activity of the prothrombinase enzyme in macrophages from mice stressed 14 days. The synthesis of proteoglycans (PG) and glycosaminoglycans (GAG) was increased in macrophages from mice stressed 8 days compared to macrophages from HCC mice and mice stressed 14 days. When macrophages from mice stressed 8 days or HCC mice were stimulated in vitro with phorbol myristate acetate (PMA) and IL-1 or PMA and IL-2, a changed PG/GAG synthesis was observed only in macrophages from the HCC animals. Furthermore, both the tumour cytotoxicity and the released tumour necrosis factor (TNF) were decreased from macrophages from mice stressed 14 days compared to HCC mice. The results suggest that the macrophages of stressed mice have an altered mode of function more complex than a simple general suppression or activation.

Animals↗
PubMed1990

Dynamics of blood components and peritoneal fluid during treatment of murine E. coli sepsis with beta-1,3-D-polyglucose derivatives. I. Cells.

Beta-1,3-D-polyglucose derivatives protect mice against otherwise lethal bacterial infections. This protective effect has previously been considered to be mediated through mononuclear phagocytes. We have now investigated the cellular composition in blood and peritoneal fluid after administration of the beta-1,3-D-polyglucose before and after challenge with Escherichia coli. In animals treated with beta-1,3-D-polyglucose derivatives, the total white cell number was significantly increased in both blood and peritoneal fluid before and after challenge with E. coli. The increased total cell number was mainly the result of raised levels of granulocytes. The effects of beta-1,3-D-polyglucose-derivatized microbeads (GDM) and soluble aminated beta-1,3-D-polyglucose (AG) were similar. Bacterial counts in peripheral blood in GDM- and AG-treated animals increased with 6 h after challenge and approached zero after 24 h. In untreated animals the bacterial counts increased gradually until the animals died after about 12 h. Bacterial counts in peritoneal fluid of GDM- and AG-treated animals declined to zero after 24 h. In untreated animals there was a slight increase in bacterial counts until the animals died after about 12 h. By using radioactive labelling, we localized the bacterial as well as the beta-1,3-D-polyglucose derivatives during the period following injection. Particle-bound beta-1,3-D-polyglucose was recovered mainly in the milky spots of the omentum. A conspicuous number of bacteria were also recovered in the milky spots. The soluble aminated beta-1,3-D-polyglucose was recovered mainly in the liver. However, on a weight basis, the greatest concentration of radioactivity was in the milky spots.

Animals↗
PubMed1990

Dynamics of blood components and peritoneal fluid during treatment of murine E. coli sepsis with beta-1,3-D-polyglucose derivatives. II. Interleukin 1, tumour necrosis factor, prostaglandin E2, and leukotriene B4.

The influences of pretreatment with beta-1,3-D-polyglucose derivatives on levels of cytokines and arachidonic acid metabolites in body fluids in experimental peritonitis in mice are reported. Peritonitis was induced by an intraperitoneal injection of 10(8) live Escherichia coli. Pretreated animals survived the infection, untreated animals died about 12 h after inoculation with E. coli. Levels of IL-1 in plasma and peritoneal fluid, measured by cytotoxicity assay of the HT-2 cell line, increased significantly during the first 48 h after intraperitoneal treatment with beta-1,3-D-polyglucose-derivatized microbeads (GDM) or soluble, aminated beta-1,3-D-polyglucose (AG). After subsequent challenge with E. coli, the levels of IL-1 were significantly lower than in untreated animals. There was no increase in levels of TNF after treatment with GDM or AG, measured by cytotoxicity assay of the WEHI clone 13 cell line. After challenge with E. coli, TNF in plasma and peritoneal fluid was significantly lower compared with untreated animals. Both PGE2 and LTB4, measured by radioimmunoassay kits, were increased in peritoneal fluid after treatment with GDM and AG. After challenge with E. coli, PGE2 and LTB4 in peritoneal fluid increased to about half the concentration of infected control animals. Intraperitoneal injection of indomethacin to pretreated animals resulted in increased levels of IL-1 and TNF and decreased levels of PGE2 following challenge with E. coli. The levels of IL-1 and TNF remained elevated until the animals died after about 12 h. These studies demonstrate that the raised levels of arachidonic acid metabolites after pretreatment with GDM or AG seem to inhibit the otherwise lethal elevation of IL-1 and TNF in body fluids which is seen in untreated animals.

Animals↗
PubMed1989

Binding of metastatic colon carcinoma cells to liver macrophages.

The liver is frequently colonized by metastatic tumor cells despite its dense population of macrophages (Kupffer cells). We have studied the interactions between metastatic colon carcinoma cells (DHD) and syngeneic Kupffer cells under different experimental conditions in vitro. In an adhesion assay the binding of DHD cells to Kupffer cell monolayers was shown to be time and temperature dependent, reaching a maximum level after about 90 min of incubation at 37 degrees C. In contrast, only a low level of binding could be observed at 4 degrees C. The level of binding could be increased by pretreatment of the Kupffer cells with phorbol 12-myristate 13-acetate. A firm interaction between the two cell types was shown to be dependent on the presence of calcium- and trypsin-sensitive structures on the surface of the Kupffer cells. Pretreatment of the macrophages with the cytoskeletal inhibitors colchicine and cytochalasin B was also found to reduce significantly the binding of tumor cells. This binding was also inhibited to a large extent by D-mannose and N-acetyl-D-galactosamine. The Kupffer cells were not cytotoxic against the colon carcinoma cells.

Animals↗
PubMed1989

The modulatory effect of lipoproteins on the release of interleukin 1 by human peritoneal macrophages stimulated with beta-1,3-D-polyglucose derivatives.

Human peritoneal macrophages were stimulated in vitro with beta-1,3-D-polyglucose-derivatized microbeads (GDM) or soluble aminated beta-1,3-D-polyglucose (AG) in combination with lipoproteins. The release of interleukin 1 (IL-1) was analysed in cell supernatants in a thymocyte proliferation assay. We report that the release of IL-1 is markedly enhanced in macrophages stimulated with polyglucose in either form in combination with native low-density lipoprotein (LDL) or acetyl LDL at a concentration of 100 micrograms/ml. By increasing the amount of lipoproteins up to 10-fold, the IL-1 release decreased sharply. There was only a slight increase in activity when high-density lipoprotein (HDL) or very low-density lipoprotein (VLDL) were added. Other stimulatory agents, such as gamma interferon (IFN-gamma) and lipopolysaccharide (LPS) showed about half the activity of polyglucose. There was no significant difference between native LDL and acetyl LDL in potentiating effect. Our observations also suggest that the potentiating effect of LDL or acetyl LDL is not dependent on binding to their specific receptors. These findings provide a connection between macrophages, lipoproteins, and cytokines with regard to their role in the inflammatory response.

Adjuvants, Immunologic↗
PubMed1989

Evidence that tumor necrosis induced by aminated beta 1-3D polyglucose is mediated by a concerted action of local and systemic cytokines.

Aminated beta 1-3D polyglucose (AG) causes regression of Meth A sarcoma in syngeneic mice when injected systemically on day 7 after tumour inoculation. AG does not concentrate in the tumour, but distributes throughout the body. AG treatment causes release of large amounts of interleukin 1 (IL-1) both in vivo and in macrophage cultures in vitro. AG is a weak stimulus for tumour necrosis factor (TNF) release both in vitro and in vivo. However, tumour tissue and sera from untreated mice on days 3 and 7 after inoculation contain significant amounts of TNF, whereas tumour tissue and sera on day 14 contain insignificant amounts of TNF. This correlates exactly with the sensitivity to AG treatment. IL-1, and TNF when injected locally cause reduction in tumour blood circulation and also shrinkage of the tumour. All these facts taken together indicate that the tumour circulatory failure and necrosis induced by AG are mediated by local TNF-unrelated to the treatment--potentiated by systemic cytokines triggered by the AG.

Animals↗
PubMed1987

Semisoluble aminated glucan: long-term efficacy against an intraperitoneal E. coli challenge and its effect on formation of abdominal adhesions.

The first part of this study in the rat was designed to assess the immediate and, in particular, the long-term effects of semisoluble aminated glucan (SAG) with regard to an intraperitoneal (i.p.) E. coli challenge and side-effects. The severity of the E. coli peritonitis was evaluated by quantification of the concomitant bacteremia. The animals randomly received either 10 ml normal saline i.p. (controls) or 10 ml (50 mg) SAG i.p. (experimental groups). It was found that SAG had no immediate protective effect against the infectious challenge as no difference was detected in the bacterial clearance between saline- and SAG-treated rats at day 0. However, 2 days after injection of saline/SAG a substantial protection of SAG was noted as no blood-borne bacteria could be detected at 1, 2, 3, 4 and 5 h after the E. coli challenge in SAG-treated animals, whereas by contrast matching blood cultures were positive in all controls. A likewise protective effect against E. coli bacteremia of a single i.p. injection of SAG was demonstrated at 7, 21, and 49 days after the administration of the compound. During the 7-week experimental period no clinical side-effects of SAG were observed. At autopsy (days 0, 2, 7, 21, and 49, respectively) no gross pathologic conditions were found. Lung, spleen, and kidney sections from SAG-treated rats were normal, whereas tiny granulomas were exhibited in liver sections, possibly related to the hyperfunctional macrophage state which SAG induced. The second main object of the study was to evaluate SAG's effect on adhesion formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1979

Uptake and degradation of mast-cell granules by mouse peritoneal macrophages.

35S-labelled mast-cell granules isolated from mouse mastocytomas were added to mouse macrophages in vitro. The granules were avidly phagocytosed, and subsequently the radioactivity was released to the medium as inorganic [35S]sulphate. After pulse-labelling, a total of about 80% of the cell-associated radioactivity was thus released in the course of 24 h, indicating an extensive breakdown of the sulphated polysaccharides, mainly heparin, present in the granules. The uptake of the mast-cell granules caused pronounced, but reversible, spreading of the macrophages.

Animals↗
PubMed1978

Difference in the effect of immobilized ligands on the Fc and C3 receptors of mouse peritoneal macrophages in vitro.

The function of the Fc and C3 receptors on the free surface of normal and endotoxin activated mouse peritoneal macrophages seeded on glass bound antibody--antigen (AbAg) complexes or complement was examined. We found that the glass bound AbAg complexes interfered with attachment and internalization of particles recognized by the Fc receptor. The C3 receptor function in these cells was not affected. On the other hand, normal and activated macrophages seeded on glass bound complement showed no change in the function of the C3 and the Fc receptors.

Animals↗