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T Lyberg

Publications and source records attributed to T Lyberg.

At least 163 records · Page 9Linked to original sources
PubMed1983

Cellular cooperation in endothelial cell thromboplastin synthesis.

Endothelial cells from human umbilical veins produce a procoagulant identified as thromboplastin (tissue factor, factor III) when stimulated with the phorbol ester 12-0-tetradecanoyl-phorbol-13-acetate (TPA), phytohaemagglutinin (PHA) or endotoxin, Inducible thromboplastin synthesis (i.e. synthesis of the protein component of thromboplastin, apoprotein III) was totally inhibited by cycloheximide and actinomycin D, indicating that de novo protein and RNA syntheses are necessary. Serum enhanced the induced apoprotein synthesis. Of the total thromboplastin activity in homogenates of stimulated endothelial cells, about 50--70% was available on the cell surface for interaction with other coagulation factors, inactivation by trypsin and neutralization with antiserum against apoprotein III. Induced synthesis of thromboplastin in endothelial cells was 2--7-fold enhanced by the presence of several other cell types in optimal ratio 4--10 cells per endothelial cell. Some of these cell types were themselves thromboplstin producers (U-937, U-937-4), some were not inducible (lymphocytes, granulocytes and the lymphoblast lines Daudi and Molt 4). This enhancing effect was also seen with cell-free culture supernatants, but these were generally somewhat less effective than the intact cells. Supernatants derived from cells cultured in the presence of TPA, PHA or endotoxin were in most cases more effective than supernatants from unstimulated cells.

Cell-Free System↗
PubMed1983

Thromboplastin as a marker for monocyte differentiation.

The thromboplastin synthesis of the human monocytoid cell line U-937 and its two subclones designated U-937-3 and U-937-4 has been studied. U-937-4 seems by several functional criteria to represent a more advanced stage of monocyte differentiation than the original U-937. U-937-3 appears to be arrested at an even more immature stage than the original population. The basal thromboplastin activity was higher in U-937-4 than in U-937-3 or U-937 cells (7.0 +/- 1.9 (SEM), 1.0 +/- 0.2 and 1.6 +/- 0.6 units/mg protein, respectively) although not as high as in human normal monocytes (14.1 +/- 2.4). The thromboplastic expression of the two clones was maximal when cells were in logarithmic growth. Both clones responded with a weak to moderate thromboplastin synthesis upon addition of stimulants like phytohaemagglutinin (PHA), immune complexes or endotoxin. Thromboplastin production was also potentiated in the presence of lymphocytes. The supporting effect of lymphocytes was strong in the case of U-937-3 as well as in U-937 cells, but less pronounced in U-937-4 cells as it also is in human monocytes. The thromboplastin response after PHA stimulation was more rapid in U-937-4 cells (maximal after 4-8 h) than in U-937 or U-937-3 cells (12-16 h). Human monocytes also responds quickly to PHA (maximally 4 h). Total phospholipid content and the relative distribution of individual phospholipids were essentially similar in U-937-3, U-937-4 and U-937. With regard to thromboplastin production, U-937-4 cells seem to be more monocyte-like than the more immature cells U-937-3 and U-937. It is concluded that thromboplastin seems to be a useful marker for monocyte differentiation.

Antigen-Antibody Complex↗
PubMed1983

Macrophage heterogeneity in thromboplastin response.

The procoagulant activities of non-elicited mouse monocytes/macrophages from four anatomical localizations were compared. These cell populations were further examined for their ability to increase their procoagulant activity on exposure to endotoxin or phytohaemagglutinin (PHA). Peritoneal macrophages exhibited the highest basal procoagulant activity. Their activity was further enhanced by stimulation with endotoxin and PHA, but marked strain differences were noted. This procoagulant has been identified as tissue thromboplastin. Isolated adherent spleen cells, peripheral blood monocytes or lung alveolar macrophages had a low basal procoagulant activity that did not increase on exposure to PHA or endotoxin. The identity of the weak procoagulant in these cells is uncertain. The presence of lymphocytes in the macrophage cultures (4:1 ratio) enhanced slightly (1.3 to 1.5-fold) the response of peritoneal macrophages to endotoxin or PHA but did not significantly influence the procoagulant activity of the other macrophage subpopulations under the conditions tested. These results demonstrate heterogeneity among different macrophage subpopulations with regard to cellular procoagulant expression.

Animals↗
PubMed1983

Synthesis of thromboplastin (factor III) in mouse placental cells in vitro.

Mouse placental cells have been isolated and grown in cultures. These cells produce a procoagulant which is identical to thromboplastin (factor III) by two criteria. The procoagulant activity increases with time, culminating on the 5th day of culture. The increase is inhibited by cycloheximide, alpha-amanitin, and actinomycin D, showing that de novo synthesis of protein and RNA is necessary. About 90-95% of the total cellular thromboplastin activity in whole cells is available for inactivation by particle-bound trypsin and thus present on the cell surface. Endotoxin and phytohaemagglutinin did not further increase the procoagulant activity.

Amanitins↗
PubMed1983

The role of cellular cooperation in thromboplastin synthesis.

Increasing evidence [1, 2, 3] demonstrates the clinical importance of monocyte thromboplastin synthesis in the pathogenesis of thrombosis and disseminated intravascular coagulation. Among the first to describe this was the group of the late F Josso [4, 5]. In addition, monocytes and macrophages appear to contribute to fibrin deposition in inflammatory lesions [6, 7]. Several procoagulant substances have been reported to appear in monocyte cultures. Among these, thromboplastin is the most potent and probably also the most important and well studied. Based as it is on our own work, this brief review will deal only with thromboplastin. It is a phospholipid-protein complex, consisting in human material of one species of protein (apoprotein III) mol. wt. approximately 52,000 surrounded by phospholipids [8] in an optimal molecular ratio of apoprotein:phospholipids of approximately 1:80 [9]. Apoprotein III is an integral membrane glycoprotein which apparently is located mainly on the outside of the plasma membrane. The molecular weight has recently been confirmed in our laboratory by Western blotting, using a monoclonal antibody to apoprotein III developed here (Johnsen, unpublished).

Animals↗
PubMed1983

Is lymphocyte co-operation necessary for thromboplastin synthesis by human monocytes?

Human monocytes synthesize the protein component of thromboplastin and express increased procoagulant activity when appropriately stimulated in vitro. The activity reached maximum between 2 and 20 h depending on the stimulant used. The presence of lymphocytes (lymphocyte: monocyte ratio 4:1) enhanced this activity only very slightly (up to 1.3-fold) at the time of maximal monocyte thromboplastin expression. Lymphocytes had a marked potentiating effect on PHA stimulation that became clearly evident after 12 h, at which time the thromboplastin response of monocytes alone to PHA had subsided. The thromboplastin activity of monocytes remained at a high level for 24-40 h in the presence of PHA or endotoxin and lymphocytes, but lymphocytes did not influence the early (4-8 h) thromboplastin response. Neither did lymphocytes alter the magnitude or the time course of the response when monocytes were stimulated with PPD, TPA or immune complexes. The lymphoblastoid cell line Molt 4 (T cell like) was as effective as lymphocytes, Daudi cells (B cell like) were slightly less effective. The enhancement of thromboplastin activity in PHA-stimulated monocytes could be induced also by conditioned medium from PHA stimulated lymphocytes. We conclude that freshly isolated monocytes synthesize thromboplastin directly upon interaction with a stimulant, and are not dependent on a helper effect of lymphocytes or lymphocyte products. Such help, however, will prolong the ability of the monocytes to respond.

Antigen-Antibody Complex↗
PubMed1982

Synthesis of thromboplastin protein by a murine macrophage-like cell line.

The established murine macrophage cell line J-774.1 responds to endotoxin with synthesis of thromboplastin apoprotein. The response develops in the absence of added lymphocytes and there is no increased responsiveness in cocultures of J-774.1 cells and BALB/c lymphocytes. J-774.1 cells therefore do not depend on lymphocyte cooperation for their response to endotoxin.

Animals↗
PubMed1982

Effect of immune complex-containing sera from patients with rheumatic diseases on thromboplastin activity of monocytes.

Monocytes isolated from peripheral blood of patients with various rheumatic diseases and circulating immune complexes (IC) developed a significantly higher thromboplastin (tissue factor) activity than normal cells when cultured in vitro without inducers, but normal cells responded more strongly with thromboplastin production upon stimulation with IC or phytohaemagglutinin (PHA). Sera from patients with rheumatic diseases and circulating IC induced a significant increase in the thromboplastin activity of normal monocytes. Lysozyme release from patient monocytes was significantly lower than the release from control cells when stimulated with IC. Patient sera contained higher amounts of lysozyme than normal sera, indicating lysozyme release in vivo. These data suggest that activation of monocytes in vivo by IC may take place. The increased expression of thromboplastin in monocytes/tissue macrophages may be important for the development of microvascular thrombosis and fibrin deposition seen in chronic inflammatory lesions.

Adolescent↗
PubMed1982

Synthesis of thromboplastin by U-937 cells.

A human monocytoid cell line (U-937) produces a procoagulant identified as thromboplastin when stimulated with phytohaemagglutinin (PHA), endotoxin, immune complexes, the phorbol ester 12-O-tetradecanoyl-phorbol 13-acetate (TPA) or the divalent ionophore A 23187. The basal thromboplastin expression of these cells and the increased activity induced by the stimulants were dependent on supply of fresh medium suggesting that the synthetic rate was highest when the cells were in logarithmic growth. Inducible thromboplastin synthesis was inhibited by actinomycin D or cycloheximide, indicating dependence on messenger RNA and protein synthesis. Differentiation of the cells in the macrophage direction by TPA did not make the cells more responsive to PHA. Thromboplastin induction in U-937 cells was potentiated by the presence of lymphocytes, especially when stimulated with PHA or endotoxin. This supporting effect was also obtained by conditioned medium from lymphocyte cultures, suggesting a role for a soluble lymphocyte product.

Antigen-Antibody Complex↗
PubMed1982

Thromboplastin (factor III) activity in human monocytes induced by immune complexes.

Immune complexes induced the synthesis of apoprotein III, the protein component of tissue thromboplastin (tissue factor), in human monocytes cultured in vitro. The response was maximal (11.1 +/- 1.7 fold increase (mean +/- SEM) when immune complexes were formed at antigen/antibody equivalence. Immune complexes formed with the antigen-binding fragments (F(ab')2) of immunoglobulins induced a 4.7 +/- 1.4 fold activity increase, suggesting that another signal mechanism in addition to the Fc-receptor may be involved.

Animals↗
PubMed1982

Effect of purified protein derivative and sonicates of Mycobacterium leprae and Mycobacterium bovis BCG on thromboplastin response in human monocytes in vitro.

Human monocytes isolated from peripheral blood responded with increased thromboplastin expression upon stimulation in vitro with three mycobacterial antigens: tuberculin purified protein derivative and sonicates of Mycobacterium boviS BCG and Mycobacterium leprae. The stimulating principle of mycobacteria is probably a cell wall constituent since crude extracts of cell walls were 2.5 to 25 times more potent in stimulating thromboplastin synthesis than were whole sonicates. This thromboplastin response was inhibited by inhibitors of RNA and protein synthesis, dexamethasone, and agents that caused elevation of intracellular cyclic AMP. The presence of lymphocytes did not enhance the monocyte thromboplastin response significantly during the first 24 h of incubation. For M. bovis BCG and M. leprae sonicates, the thromboplastin response correlated with general activating effects measured by determining the release of lysozyme and beta-glucuronidase. The role of thromboplastin in chronic inflammatory reactions is discussed.

Antigens, Bacterial↗
PubMed1981

Phorbol esters induce synthesis of thromboplastin activity in human monocytes.

12-O-Tetradecanoylphorbol 13-acetate (TPA), phorbol 12,13-diacetate and phorbol 12,13-didecanoate were all potent inducers of thromboplastin activity in human monocytes in vitro, whereas 4 alpha-phorbol 12,13-didecanoate and 4 alpha-phorbol had no such effect. A concomitant increase in titrable apoprotein III antigen was found (apoprotein III is the protein component of thromboplastin). The increase was inhibited by cycloheximide and actinomycin D and partly by alpha-amanitin. The increase of thromboplastin activity was therefore most likely due to synthesis de novo of apoprotein III. The response was approximately halved in the absence of serum or Ca2+. Retinol had a weak inhibitory effect, and retinoic acid was inhibitory only at concentrations that also induced signs of cytotoxicity. TPA caused an initial rise in monocyte cyclic AMP concentration of about 90-120 min duration. No increase in 45Ca2+ influx was induced over 2 h. Good correlation exists between induction of apoprotein III synthesis in monocytes in vitro and mouse skin-tumour promotion in vivo by the various phorbol derivatives. Substances inactive in tumour promotion do not induce the synthesis of apoprotein III. General activating and cytotoxic effects of TPA were monitored by determining release of lysozyme, beta-glucuronidase and lactate dehydrogenase.

Apoproteins↗
PubMed1980

Lectin stimulation of tissue thromboplastin activity in human monocytes in vitro.

Lectins (phytohaemagglutinin, concanavalin A and wheat germ agglutinin) trigger an increase in tissue thromboplastin activity of human monocytes in vitro. The presence of serum was not necessary and did not enhance the activity. The increase was inhibited by cycloheximide and actinomycin D, suggesting that de novo protein synthesis is involved.

Agglutinins↗
PubMed1978

Purification of the first component of guinea-pig complement by gel chromatography.

A method has been described for the purification of the first component (C1) of complement from guinea-pig serum. The procedure consists in euglobulin precipitation followed by gel filtration on agarose columns. The final product has low protein content and high specific activity. The protein obtained by this procedure has a molecular weight of about one million and has been further characterized using immunochemical and polyacrylamide gel electrophoresis techniques. The protein reacts with anti-C1 antiserum and forms the EAC1, 4-intermediate. The experiments indicated the existence of electrophoretic variants of C1. The dissociation of the C1 molecule by increasing the ionic strength is confirmed. The described procedure appears to be a useful method of obtaining functionally purified C1.

Animals↗
PubMed1977

Isotope-labelled alpha-amino-isobutyric acid as an indicator in cytotoxicity tests.

The effect of rabbit antisera on the uptake and release of alpha-amino-isobutyric acid (AIBA) in LS- and P-388 cells was investigated. In the presence of homologous antiserum and complement, the uptake of AIBA was inhibited. In the absence of complement, no effect of antiserum was seen. Using prelabelled cells, the efflux of AIBA was greatly accelerated in the presence of antiserum and complement. The AIBA-uptake method was compared with the trypan blue exclusion test and the 51Cr release technique. The AIBA-uptake method was more sensitive in quantitative cytotoxic studies.

Aminoisobutyric Acids↗