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R Seljelid

Publications and source records attributed to R Seljelid.

At least 91 records · Page 5Linked to original sources
PubMed1984

Lysosomal glycosidases in mouse peritoneal macrophages stimulated in vitro with soluble and insoluble glycans.

Mouse peritoneal macrophages stimulated with insoluble glycans in vitro release high amounts of acid hydrolases, N-acetyl-beta-D-glucosaminidase, beta-D-glucuronidase, and beta-D-galactosidase. The most potent of the stimulatory glycans is a beta-1,3-D-glucan isolated from yeast cell walls. Up to 50% of total enzyme activity was found in the medium after stimulation with this glycan for three days. Agarose, another insoluble glycan containing an alternating sequence of the disaccharide beta-1,3-D-galactose-alpha-1,4-3,6-anhydro-L-galactose units was less potent. The soluble beta-1,3-D-glucan laminaran, which also contains small amounts of mannitol, was not able to induce release of acid glycosidases from macrophages. The release was independent of serum since macrophages cultured under serum-free conditions showed nearly the same pattern of enzyme activities, both in the cells and media. There was no increased release of the acid hydrolase alpha-D-mannosidase after stimulation with the insoluble beta-1,3-D-glucan for three days. The release of the lysosomal glycosidases was not due to cell death, since only small amounts of the cytoplasmic enzyme lactate dehydrogenase were found in the culture media. Insoluble polystyrene latex particles were not able to stimulate mouse macrophages to release lysosomal glycosidases. Tritiated glycans (amylose, dextran, laminaran, the insoluble beta-1,3-D-glucan, and agarose) and the p-nitrophenyl-glycopyranoside derivatives were used as substrates to investigate whether the macrophages contained or released glucanases capable of degrading alpha-1,4-D-glucans, alpha-1-6-D-glucans, beta-1,3-D-glucans, and agarose respectively. We conclude that the glycans were not degraded in macrophage cultures during the time period tested nor were the enzymes induced in macrophages by the glycans during in vitro culture for seven days.

Animals↗
PubMed1984

Stimulatory effect of immobilized glycans on macrophages in vitro.

Mouse macrophages were cultured on chemically modified plastic dishes. On dishes covered with immobilized glycans, the macrophages were stimulated as judged by increased 14C-glucosamine incorporation, increased cytostatic and cytolytic capacities and by morphology as seen by scanning electron microscopy. The corresponding soluble glycans did not have the capacity to stimulate macrophages as measured by these criteria. Plastic surfaces covered with polyethylenimine showed stimulation of the macrophages with regard to some of the parameters measured. These results may indicate that the stimulation is a multistep process and that, contrary to earlier findings, it is not a prerequisite for stimulation that the glycan be intracellular. The results support the idea that a fixed steric arrangement of glycans is necessary for the stimulation of macrophages in vitro.

Amylose↗
PubMed1983

Changes in glycosaminoglycan biosynthesis during differentiation in vitro of human monocytes.

Monocytes isolated from human blood were maintained in vitro on plastic culture dishes. After 3-4 days, adherent cells displayed morphological changes previously attributed to differentiation of the cells into histiocytes. 35S-labelled glycosaminoglycans were isolated after incubation of the cells with inorganic [35S]sulphate. Polysaccharide recovered from the culture medium after labelling from day 0 to day 2 or from day 5 to day 7 in vitro was approximately 90% galactosaminoglycan (resistant to deamination by HNO2), irrespective of labelling period. Whereas day-0-2 material was extensively degraded to disaccharide on incubation with the bacterial eliminase chondroitinase AC, a significant portion, about 30%, of the day-5-7 material resisted degradation under the same conditions. The resistant portion was readily depolymerized by treatment with chondroitinase ABC and may be dermatan sulphate. Paper electrophoresis and paper chromatography of the disaccharides obtained by eliminase digestion identified the day-0-2 labelled galactosaminoglycan as chondroitin 4-sulphate. In contrast, the corresponding day-5-7 material yielded approximately 20% disulphated disaccharide, both on digestion with chondroitinase AC and on subsequent enzymic degradation of the chondroitinase AC-resistant fraction. Further treatment of the disulphated disaccharide with chondro-4-sulphatase and chondro-6-sulphatase indicated that both sulphate groups were located on the N-acetylgalactosamine residue. In accordance with these findings, the day-5-7 polysaccharide showed a higher negative charge density than the day-0-2 material on ion-exchange chromatography. It is concluded that the novel properties acquired by the monocyte during prolonged culturing on plastic include the ability to synthesize glycosaminoglycan(s) containing 4,6-disulphated N-acetylgalactosamine units.

Carbohydrates↗
PubMed1983

Complement (C3) receptor-mediated attachment of agarose beads to mouse peritoneal macrophages and human monocytes.

We have determined the receptors on human monocytes and mouse peritoneal macrophages producing agarose binding. By using isolated human complement factors C3, B and D, agarose beads were coated with C3b. In some experiments C3b was converted to C3bi by using human serum diluted 1:20. Agarose beads coated with C3b or C3bi bound strongly to monocytes. Only agarose beads coated with C3bi were attached to mouse macrophages. Trypsinization of agarose beads coated with C3bi abolished the attachment of the beads to macrophages and monocytes, probably because of conversion of C3bi to C3d. Endocytosis by macrophages of agarose preincubated in human serum or in C5-deficient AKR mouse serum reached the same levels, indicating that the amount of C5 present in serum during preincubation is not important for the degree of endocytosis. It is concluded that internalization of agarose by macrophages is mediated via the C3bi receptor.

Animals↗
PubMed1983

Stress causes reduced natural killer activity in mice.

The natural killer (NK) activity of spleen cells from C57B1/10 mice subjected to standardized stress conditions was reduced when compared with that of untreated controls. Both the total number of nucleated spleen cells and their cytotoxic activity against an NK-sensitive target were reduced. The reduction appeared after induction of stress, and the NK activity was reduced throughout an 8-day stress period.

Animals↗
PubMed1983

Tumour-activated macrophages as effector cells in a tumour neutralization assay in vivo.

Macrophages from C3D2 or C57B1/6 mice were activated in vitro by coculture with MC1M-AA sarcoma cells or by addition of cell free tumour ascites fluid from the same tumour. After 5-7 days of in vitro activation, macrophages were harvested, mixed with MC1M-AA or B-16 melanoma cells, and reinjected into C3D2 or C57B1/6 mice respectively. Mice were evaluated for tumour development, and the early histological appearance of the B16 melanomas was studied. Activated macrophages gave a significant delay and decrease in tumour take when mixed with B16 melanoma cells at a tumour cell: activated macrophage ratio of 1:20. When activated macrophages were mixed with MC1M-AA cells at a tumour cell: activated macrophage ratio of 1:50, a slight delay and a significant decrease in tumour take was observed. BCG-activated macrophages did exhibit a very weak effect on MC1M-AA tumour growth. When B16 melanoma cells were injected into mice together with activated macrophages, an acute inflammatory reaction was observed at the site of injection. The organization of the tumour was delayed, and necrotic tumour cells could be found. In some cases, small islands of tumour cells escaped killing, and gave rise to delayed tumour development.

Animals↗
PubMed1982

Studies, with a luminogenic peptide substrate, on blood coagulation factor X/Xa produced by mouse peritoneal macrophages.

The formation and secretion of coagulation Factor X/Xa by mouse peritoneal macrophages was studied with a luminogenic peptide substrate (S-2613; t-butyloxycarbonylisoleucylglutamyl-gamma-piperidylglycylarginylisoluminol). Amidolysis was quantified by measuring the light emitted during oxidation of isoluminol, released by Factor Xa. A lower detection limit of about 0.5ng of Factor Xa was established; the assay was linear with enzyme concentration up to at least 100ng/ml. Factor X was determined after treatment with the Factor X-activating component of Russell's-viper (Vipera russelli) venom. Macrophages, cultured in the absence of serum, released Factor X/Xa into the culture medium. The concentration of coagulation enzyme in the medium increased in an essentially linear fashion over a period of at least 3 days, at a rate corresponding to 6-8ng produced/24h per 10(6) cells. The ratio of Factor Xa/X+Xa varied from about 60 to 100%, showing that activation of Factor X to Xa is not prerequisite to release of the enzyme from the cells. Factor Xa activity was suppressed in the presence of warfarin [3-(alpha-acetonylbenzyl)-4-hydroxycoumarin; 12.5mug/ml of medium], but could be restored by adding vitamin K (0.1mug/ml) along with the warfarin. Cultures to which Sepharose beads containing covalently bound anti-(Factor X) antibodies had been added showed decreased amounts of free Factor X/Xa in the culture medium. The missing activity could be demonstrated by incubating the recovered conjugate with the substrate peptide S-2613. Factor Xa produced by the macrophages was efficiently inactivated by heparin in the presence of antithrombin, heparin with high affinity for antithrombin being more effective than the corresponding low-affinity species.

Animals↗
PubMed1982

Rainbow trout macrophages in vitro: morphology and phagocytic activity.

The properties of macrophages from the pronephros of Rainbow trout (Salmo gairdneri Richardson) were studied in vitro. We found that phagocytes obtained from the pronephros constitute a non-homogeneous cell population. Three populations with different adherence properties were examined with special emphasis on morphology and phagocytic capacity. The differentiation of the three populations in culture was similar morphologically, and their phagocytic activity showed only small variations. The methods for cell separation and culture reported here are a useful tool for gaining better understanding of how Rainbow trout macrophages function in the immune response.

Acid Phosphatase↗
PubMed1982

Receptors for complement on echinoid phagocytes. I. The opsonic effect of vertebrae sera on echinoid phagocytosis.

The ingestion of sheep erythrocytes (SRBC) by echinoid phagocytes was greatly increased after treatment of SRBC with sera from mouse, human and fish. The opsonic principle in the sera was heat labile (56 degrees C 1/2 hr). Opsonization with mammalian sera was studied more extensively. It was dependent on pre-sensitization of SRBC with specific antibody (IgM), required Ca2+, and was inhibited by low temperature (4 degrees C). The finding that serum depleted of C 3 only opsonized very weakly strongly indicates that the opsonic principles is the complement cascade C 1-4-2-3 activated via the classical pathway, and that the opsonic effect largely coincides with the coating of SRBC with C 3b. A role of C 5 or later components was excluded, since the mouse AKR serum was C 5 deficient, and the human serum was normally treated with zymosan. When variations known to impair the opsonic function of C 3 was introduced in the opsonization procedure, a parallel inhibition was recorded on attachment of SRBC to mouse peritoneal macrophages and on ingestion of SRBC by echinoid cells. Thus C 3 receptors are probably present on echinoid phagocytes.

Animals↗
PubMed1982

Endocytosis of agarose in mouse peritoneal macrophages in vitro.

We have studied the endocytosis of tritium-labelled and of non-radioactive agarose in mouse macrophages in vitro. The endocytosis was greatest and most rapid in syngeneic mouse serum and in human serum, reaching a plateau after 12 h of incubation. Ten per cent serum was the minimum concentration giving optimal ingestion. The endocytosis appeared to be regulated by mechanisms involving complement factors C3 and B. Different pretreatments of sera, inactivating or depleting C3 and B, resulted in 70-80% reduction of endocytosis. Preincubation of agarose in untreated serum increased the endocytosis of agarose in heat-inactivated serum three-fold indicating that the essential factors were bound to agarose. Antibodies against C3 and B reduced endocytosis moderately but significantly.

Animals↗
PubMed1982

The cytotoxic effect of mouse macrophages stimulated in vitro by a beta-1,3-D-glucan from yeast cell walls.

Macrophages stimulated by an insoluble beta-1,3-D-glucan from yeast cell walls were able to destroy tumour cells as measured by the release of radioactive label from prelabelled 14C-thymidine cells. Target cells were B-16 melanoma, P-815 mastocytoma, and the L-929 cell line. A significant target cell killing by macrophages stimulated by glucan was observed after 72-96 h. The cytolysis of L-929 cells was investigated in some detail. No stable soluble cytolytic factor appeared to be released into the medium during the stimulation of macrophages by glucan, since cell-free spent medium had no cytotoxic effect on L-929 cells. The densities of the macrophage monolayers were critical for an effective target cell killing; dense cultures showed more cytotoxicity than less dense cultures. The kinetics of the development of macrophage-mediated cytotoxicity suggests a minimum stimulation period of 4 days for maximal cytolysis.

Animals↗
PubMed1982

In vitro cytotoxicity of mouse macrophages activated by coculture with syngeneic sarcoma cells.

Normal resident peritoneal macrophages from C3D2 (C3H/Tif X DBA/2) F1 mice were activated in vitro by culturing with semisyngeneic tumour cells. The tumour cells originated from a methylcholanthrene-induced sarcoma (MC1M) growing in vivo in ascites form. Macrophage-mediated cytotoxicity was evaluated after 5 days of in vitro culture, using five different target cells. Semisyngeneic (L 929), allogeneic (B16 melanoma), and xenogeneic (HeLa) tumour cell lines and normal allogeneic fibroblast cell lines (3T3, 3T6) were tested. The morphology and kinetics of the cytotoxicity reaction were studied by scanning electron microscopy and compared with release of radioactivity from 14C-thymidine-labelled target cells. The activated macrophages were able to kill the semisyngeneic, allogeneic, and xenogeneic tumour cell lines tested under conditions that did not affect normal fibroblasts. The requirement for T cells during activation of the macrophages was also tested. The cytotoxicity decreased markedly when T cells were removed from the macrophage cultures before activation or when macrophages from nude mice were used in the experiments.

Animals↗
PubMed1982

Evidence that agarose must be internalized to stimulate mouse macrophages in vitro.

Agarose stimulation of macrophages in vitro was studied. Under conditions where agarose was ingested, stimulation was detected during 24-48 h of incubation at a time when the agarose increasingly was concentrated in the perinuclear region. Removal of extracellular agarose after 24 h when endocytosis had reached a plateau did not reduce the stimulatory effect. Preincubation for 4 days with dextran sulphate in concentrations reported to inhibit phagosome-lysosome fusion potentiated strongly the stimulatory effect. In all situations in which agarose was not internalized--in teflon tubes where the cells remain in suspension, on glass cover slips with inhibitors (2-deoxy-D-glucose, cytochalasin B), or with large, noningestible Sepharose beads--no stimulation was recorded. The possibility is discussed that stimulation of macrophages by agarose may be related to complement activation in phagosomes.

Animals↗
PubMed1981

Production of immune interferon (type II) in cocultures of mouse peritoneal macrophages and syngeneic tumour cells.

Mouse peritoneal macrophages were activated by coculture with syngeneic methylcholanthrene-induced sarcoma cells [7], which grow as an ascites tumour in C3D2 mice [3]. During 4-5 days of cocultivation tumour cells progressively died, leaving highly activated macrophages. Cell-free supernatant harvested from the cultures contained larger amounts of interferon than either macrophages or tumour cells cultivated alone. Peak activity of interferon occurred on day 2. Non-adherent cells cultivated together with tumour cells did not produce interferon. Removal of all non-adherent cells from macrophage cultures and host cells from tumour cell suspension did not abolish interferon production. The macrophages thus seem to be the interferon-producing cells, but the possibility that the very few remaining lymphocytes may cooperate with the macrophages in interferon production cannot be totally ruled out. The interferon produced could not be inactivated by antibodies against virus-induced interferon and was destroyed by treatment at pH 2, indicating that the interferon was not of the alpha or beta type.

Animals↗