scholarly journals The endotoxin-induced procoagulant of mouse exudate macrophages: a factor-X activator

Blood ◽  
1983 ◽  
Vol 62 (2) ◽  
pp. 333-340 ◽  
Author(s):  
JW Jr Shands
Keyword(s):  
Tissue Factor ◽  
Culture Supernatant ◽  
Factor Vii ◽  
Mouse Tissue ◽  
Factor X ◽  
Macrophage Culture ◽  
Cellular Factor ◽  
Culture Supernatants ◽  
Bovine Factor

Abstract The properties of mouse macrophage procoagulant induced by endotoxin in vitro were studied by the acceleration of clotting and by chromogenic assays using as substrates human plasma and bovine components, which are not activated by mouse tissue factor. Maximal macrophage procoagulant activity occurred when activated cells were lysed in culture supernatant fluids, suggesting the interaction of cellular and supernatant factors. This procoagulant was clearly able to activate bovine factor X. The procoagulant also appeared to have prothrombinase activity. However, additional experiments suggested that the bulk of this activity was due to the activation of factor X contaminating the prothrombin. The production of the procoagulant was inhibited by warfarin (5 microM). Its activity was inhibited by 1 mM diisopropylfluorophosphate and unaffected by iodoacetamide, indicating that the procoagulant is a serine protease. Macrophage culture supernatants contained factor-VII-like activity. Neither mouse tissue factor nor macrophage culture supernatants alone activated bovine factor X. The two combined served as an efficient factor-X activator. Active supernatant factor (factor-VII-like) was not produced by macrophages cultured in the presence of warfarin, while the production of the macrophage cellular factor was unaffected by the presence of warfarin. I conclude that exudate macrophages cultured in vitro make and secrete factor VII or a factor-VII-like substance into the culture supernatant. When activated macrophages are lysed in this supernatant, the interaction of a cellular factor (? tissue factor) and factor VII gives rise to a factor-X activator.

scholarly journals The endotoxin-induced procoagulant of mouse exudate macrophages: a factor-X activator

Blood ◽  
1983 ◽  
Vol 62 (2) ◽  
pp. 333-340
Author(s):  
JW Jr Shands
Keyword(s):  
Tissue Factor ◽  
Culture Supernatant ◽  
Factor Vii ◽  
Mouse Tissue ◽  
Factor X ◽  
Macrophage Culture ◽  
Cellular Factor ◽  
Culture Supernatants ◽  
Bovine Factor

The properties of mouse macrophage procoagulant induced by endotoxin in vitro were studied by the acceleration of clotting and by chromogenic assays using as substrates human plasma and bovine components, which are not activated by mouse tissue factor. Maximal macrophage procoagulant activity occurred when activated cells were lysed in culture supernatant fluids, suggesting the interaction of cellular and supernatant factors. This procoagulant was clearly able to activate bovine factor X. The procoagulant also appeared to have prothrombinase activity. However, additional experiments suggested that the bulk of this activity was due to the activation of factor X contaminating the prothrombin. The production of the procoagulant was inhibited by warfarin (5 microM). Its activity was inhibited by 1 mM diisopropylfluorophosphate and unaffected by iodoacetamide, indicating that the procoagulant is a serine protease. Macrophage culture supernatants contained factor-VII-like activity. Neither mouse tissue factor nor macrophage culture supernatants alone activated bovine factor X. The two combined served as an efficient factor-X activator. Active supernatant factor (factor-VII-like) was not produced by macrophages cultured in the presence of warfarin, while the production of the macrophage cellular factor was unaffected by the presence of warfarin. I conclude that exudate macrophages cultured in vitro make and secrete factor VII or a factor-VII-like substance into the culture supernatant. When activated macrophages are lysed in this supernatant, the interaction of a cellular factor (? tissue factor) and factor VII gives rise to a factor-X activator.

scholarly journals Macrophage factor X activator formation: metabolic requirements for synthesis of components

Blood ◽  
1985 ◽  
Vol 65 (1) ◽  
pp. 169-175 ◽  
Author(s):  
JW Jr Shands
Keyword(s):  
Tissue Factor ◽  
Actinomycin D ◽  
Factor Vii ◽  
Soluble Factor ◽  
Factor X ◽  
Factor Activity ◽  
In Vitro Production ◽  
Tissue Factor Activity ◽  
Culture Supernatants

Abstract The in vitro production of factor VII-like material and of tissue factor activity by murine thioglycollate exudate macrophages was measured by amidolytic assays. Tissue factor activity was inducible by endotoxin, and its induction was inhibited by 1 microgram/mL of actinomycin D, 10 micrograms/mL of cycloheximide, and 0.2 micrograms/mL of tunicamycin. Soluble factor VII-like material was secreted by macrophages into culture supernatants. The amount produced was not influenced by further activation of the cells by endotoxin, nor was its production inhibited significantly by 1 microgram/mL actinomycin D or 0.2 micrograms/mL tunicamycin. The production of the factor VII-like material was inhibited by 10 micrograms/mL of cycloheximide, and its appearance in culture supernatants was enhanced significantly by the addition of vitamin K1. When lysates of activated macrophages were suspended in ultracentrifuged culture supernatants, a particulate factor X activator was formed. Centrifugation at 100,000 g pelleted the factor X activator and left no factor VII-like material in the supernatant. The data indicate that thioglycollate-induced exudate macrophages make and excrete factor VII-like material, and this production is not modulated by further activation. However, activation of the macrophages induces tissue factor production. The factor X activator appears to result from the interaction and complexing of the soluble factor VII-like material and the membrane-bound tissue factor.

scholarly journals Macrophage factor X activator formation: metabolic requirements for synthesis of components

Blood ◽  
1985 ◽  
Vol 65 (1) ◽  
pp. 169-175
Author(s):  
JW Jr Shands
Keyword(s):  
Tissue Factor ◽  
Actinomycin D ◽  
Factor Vii ◽  
Soluble Factor ◽  
Factor X ◽  
Factor Activity ◽  
In Vitro Production ◽  
Tissue Factor Activity ◽  
Culture Supernatants

The in vitro production of factor VII-like material and of tissue factor activity by murine thioglycollate exudate macrophages was measured by amidolytic assays. Tissue factor activity was inducible by endotoxin, and its induction was inhibited by 1 microgram/mL of actinomycin D, 10 micrograms/mL of cycloheximide, and 0.2 micrograms/mL of tunicamycin. Soluble factor VII-like material was secreted by macrophages into culture supernatants. The amount produced was not influenced by further activation of the cells by endotoxin, nor was its production inhibited significantly by 1 microgram/mL actinomycin D or 0.2 micrograms/mL tunicamycin. The production of the factor VII-like material was inhibited by 10 micrograms/mL of cycloheximide, and its appearance in culture supernatants was enhanced significantly by the addition of vitamin K1. When lysates of activated macrophages were suspended in ultracentrifuged culture supernatants, a particulate factor X activator was formed. Centrifugation at 100,000 g pelleted the factor X activator and left no factor VII-like material in the supernatant. The data indicate that thioglycollate-induced exudate macrophages make and excrete factor VII-like material, and this production is not modulated by further activation. However, activation of the macrophages induces tissue factor production. The factor X activator appears to result from the interaction and complexing of the soluble factor VII-like material and the membrane-bound tissue factor.

scholarly journals Activation of human factor VII during clotting in vitro

Blood ◽  
1985 ◽  
Vol 65 (1) ◽  
pp. 218-226 ◽  
Author(s):  
LV Rao ◽  
SP Bajaj ◽  
SI Rapaport
Keyword(s):  
Tissue Factor ◽  
Glass Tube ◽  
Factor Vii ◽  
Clotting Factor ◽  
Activate Factor ◽  
Factor Xii ◽  
Factor X ◽  
Normal Plasma

Abstract We have studied factor VII activation by measuring the ratio of factor VII clotting to coupled amidolytic activity (VIIc/VIIam) and cleavage of 125I-factor VII. In purified systems, a low concentration of Xa or a higher concentration of IXa rapidly activated 125I-factor VII, yielding a VIIc/VIIam ratio of 25 and similar gel profiles of heavy and light chain peaks of VIIa. On further incubation, VIIa activity diminished and a third 125I-peak appeared. When normal blood containing added 125I- factor VII was clotted in a glass tube, the VIIc/VIIam ratio rose fivefold, and 20% of the 125I-factor VII was cleaved. Clotting normal plasma in an activated partial thromboplastin time (APTT) system yielded a VIIc/VIIam ratio of 25 and over 90% cleavage of 125I-factor VII. Clotting factor XII-deficient plasma preincubated with antibodies to factor X in an APTT system with added XIa yielded a VIIc/VIIam ratio of 19 and about 60% cleavage, which indicates that IXa, at a concentration achievable in plasma, can effectively activate factor VII. Clotting normal plasma with undiluted tissue factor yielded a VIIc/VIIam ratio of 15 to 20 and 60% cleavage of 125I-factor VII, whereas clotting plasma with diluted tissue factor activated factor VII only minimally. We conclude that both Xa and IXa can function as significant activators of factor VII in in vitro clotting mixtures but believe that only small amounts of factor VII may be activated in vivo during hemostasis.

THE "LUPUS ANTICOAGULANT" INDUCES FUNCTIONAL CHANGES IN ENDOTHELIAL CELLS AND PLATELETS

1987 ◽  
Author(s):  
Anna E Schorer ◽  
Kathleen V Watson
Keyword(s):  
Endothelial Cells ◽  
Tissue Factor ◽  
Lupus Anticoagulant ◽  
Inhibitory Effect ◽  
Clinical Syndrome ◽  
Factor Vii ◽  
Factor X ◽  
Functional Changes ◽  
Thrombin Activation

The presence of the "lupus anticoagulant" (LA) predicts a clinical syndrome of excessive arterial, venous and microvascu-lar thrombosis. LA is an antibody which reacts with negatively charged phospholipid (PL) species in vitro. Since PL is involved in many aspects of the regulation of thrombosis, we postulated that LA might modify one or more of the membrane-(PL-dependent reactions of platelets and endothelial cells (EC). Blood samples from 20 patients with a history of thrombosis were tested for the presence of LA (kaolin PTT) and titres determined. LA-positive (LA+) sera and plasma were compared to LA-negative (LA−) samples from normal donors (n=6) or patients who had lupus but no clinical thrombosis (n=4). These specimens were tested in a panel of assays. The thrombin-stimulated release of prostacyclin (PG12) from cultured human EC was markedly reduced (52%±12.5 s.e.) by preincubation of the EC with LA+ sera (30 minutes). Purified LA+ IgG from one patient reproduced this effect. Thrombin induction of EC synthesis of the procoagulant, tissue factor-which is dissociable from prostaglandin metabolism-was also inhibited by LA+ sera. Normal platelets incubated in LA+ plasma became refractory to thrombin (1 unit/ml) but retained their responsiveness to epinephrine and ADP. The reduced responsiveness to thrombin was not due to altered (specific or total) binding of thrombin. The cleavage of Factor X by Factor VII requires PL as a co-factor for the EC procoagulant, tissue factor (TF). Unlike the inhibitory effect of LA on thrombin activation of EC and platelets, this distinct membrane-(PL-) dependent function was variably enhanced by LA+ sera. Brief (20 min) exposure of EC to LA+ sera increased TF co-catalysis of Factor VII cleavage of Factor X (measured by chromogenic Xa substrate, S-2222) by up to 10 fold (p<0.05, unpaired t test). This effect was not the result of EC disruption or changes in whole-cell TF content. These data suggest multiple, complex and heterogenous effects of LA, including impaired production of PG12, impaired EC modulation, and heightened ability of endogenous EC tissue factor to initiate coagulation. These (and perhaps other) membrane-dependent effects may contribute to the tendency of LA+ patients to develop clots.

scholarly journals Activation of human factor VII during clotting in vitro

Blood ◽  
1985 ◽  
Vol 65 (1) ◽  
pp. 218-226 ◽  
Author(s):  
LV Rao ◽  
SP Bajaj ◽  
SI Rapaport
Keyword(s):  
Tissue Factor ◽  
Glass Tube ◽  
Factor Vii ◽  
Clotting Factor ◽  
Activate Factor ◽  
Factor Xii ◽  
Factor X ◽  
Normal Plasma

We have studied factor VII activation by measuring the ratio of factor VII clotting to coupled amidolytic activity (VIIc/VIIam) and cleavage of 125I-factor VII. In purified systems, a low concentration of Xa or a higher concentration of IXa rapidly activated 125I-factor VII, yielding a VIIc/VIIam ratio of 25 and similar gel profiles of heavy and light chain peaks of VIIa. On further incubation, VIIa activity diminished and a third 125I-peak appeared. When normal blood containing added 125I- factor VII was clotted in a glass tube, the VIIc/VIIam ratio rose fivefold, and 20% of the 125I-factor VII was cleaved. Clotting normal plasma in an activated partial thromboplastin time (APTT) system yielded a VIIc/VIIam ratio of 25 and over 90% cleavage of 125I-factor VII. Clotting factor XII-deficient plasma preincubated with antibodies to factor X in an APTT system with added XIa yielded a VIIc/VIIam ratio of 19 and about 60% cleavage, which indicates that IXa, at a concentration achievable in plasma, can effectively activate factor VII. Clotting normal plasma with undiluted tissue factor yielded a VIIc/VIIam ratio of 15 to 20 and 60% cleavage of 125I-factor VII, whereas clotting plasma with diluted tissue factor activated factor VII only minimally. We conclude that both Xa and IXa can function as significant activators of factor VII in in vitro clotting mixtures but believe that only small amounts of factor VII may be activated in vivo during hemostasis.

scholarly journals Characterization of the inhibition of tissue factor in serum

Blood ◽  
1987 ◽  
Vol 69 (1) ◽  
pp. 150-155 ◽  
Author(s):  
GJ Jr Broze ◽  
JP Miletich
Keyword(s):  
Tissue Factor ◽  
Factor Viia ◽  
Factor Xa ◽  
Inhibitory Effect ◽  
Factor Vii ◽  
Factor X ◽  
Human Hepatoma Cells ◽  
Proteolytic Activation

Tissue factor (TF) is a lipoprotein cofactor that markedly enhances the proteolytic activation of factors IX and X by factor VIIa. The functional activity of TF is inhibited by serum in a time- and temperature-dependent fashion. The inhibitory effect is also dependent on the presence of calcium ions and can be reversed by calcium chelation (EDTA) and dilution, thus excluding direct proteolytic destruction of TF as the mechanism for inhibition. Using crude TF, serum immunodepleted of factor VII, and serum depleted of the vitamin K- dependent coagulation factors by BaSO4 absorption, it is shown that TF factor inhibition requires the presence of VII(a), X(a), and an additional moiety contained in barium-absorbed serum. When each of the other required components were at saturating concentrations, half- maximal inhibition of TF occurred in reaction mixtures containing 2% (vol/vol) of TF at a factor VII(a) concentration of 4 ng/mL (80 pmol/L), a factor X concentration of 50 ng/mL (850 pmol/L), and a concentration of barium-absorbed serum of 2.5% (vol/vol). Catalytically active factor Xa appeared to be required for the generation of optimal TF inhibition. The results are consistent with the conclusions of Hjort that barium-absorbed serum contains a moiety that inhibits the VIIa- Ca2+-TF complex. The role of factor X(a) in the generation of the inhibitory phenomenon remains to be elucidated. The inhibitor present in serum (plasma) may in part be produced by the liver in vivo since cultured human hepatoma cells (HepG2) secrete this inhibitory activity in vitro.

Activated Peripheral Mononuclear Cells Plus Soluble Plasma Tissue Factor Activate Factors VII and X in Cardiac Surgical Wounds.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 806-806
Author(s):  
Robert W. Colman ◽  
Mohammad M.H. Khan ◽  
Takashi Hattori ◽  
L. Henry Edmunds4
Keyword(s):  
Cardiac Surgery ◽  
Tissue Factor ◽  
Thrombin Generation ◽  
Mononuclear Cells ◽  
Factor Vii ◽  
Activate Factor ◽  
Factor X ◽  
Complex Wound ◽  
Activated Monocytes

Abstract Objectives: This study examines the role of pericardial wound monocytes in thrombin generation during clinical cardiac surgery with cardiopulmonary bypass (CPB). Background: The mechanism by which wound mononuclear cells rapidly express procoagulant activity is unexplained. Methods: Factor VII activation (FVIIa) was measured using recombinant, truncated, soluble tissue factor (rsTF) and various blood cells in vitro. FVIIa was also measured with monocytes and soluble plasma tissue factor taken before CPB and simultaneously from the pericardial wound and perfusion circuit during CPB in thirteen patients. Results: RsTF in combination with monocytes, but not platelets, neutrophils or red cells, accelerates activation of FVII beginning at 1 pmole/L rsTF. Less than 1% rsTF is bound, yet catalytic activity peaks at 7 minutes and decays afterwards. In wound plasma, monocytes are activated (MCP-1 = 29.5 ± 2.1 pmoles/L) and wound plasma tissue factor (wpTF) is substantially elevated (3.64 ± 0.45 pmoles/L) with 81.7% in the supernatant and 18.3% in microparticles. By Western blot all forms of plasma TF migrate at Mr 65 kDa [TF/FVII(FVIIa) complex]. Wound monocytes and C5a activated prebypass or perfusate monocytes plus wpTF convert all available FVII to FVIIa. Activated monocytes plus supernatant TF/FVII(VIIa) more efficiently activate factor X than microparticle TF/FVII(FVIIa). The correlation coefficient (r) between wound thrombin generation (F1.2) and wpTF is 0.944 (p = 0.0004). Conclusions: During clinical cardiac surgery with CPB wound monocytes plus wpTF or microparticle-free, protein fragments of wound tissue factor preferentially accelerate activation of FVII and FX. This system represents a new mechanism of thrombin generation.

scholarly journals Characterization of the inhibition of tissue factor in serum

Blood ◽  
1987 ◽  
Vol 69 (1) ◽  
pp. 150-155 ◽  
Author(s):  
GJ Jr Broze ◽  
JP Miletich
Keyword(s):  
Tissue Factor ◽  
Factor Viia ◽  
Factor Xa ◽  
Inhibitory Effect ◽  
Factor Vii ◽  
Factor X ◽  
Human Hepatoma Cells ◽  
Proteolytic Activation

Abstract Tissue factor (TF) is a lipoprotein cofactor that markedly enhances the proteolytic activation of factors IX and X by factor VIIa. The functional activity of TF is inhibited by serum in a time- and temperature-dependent fashion. The inhibitory effect is also dependent on the presence of calcium ions and can be reversed by calcium chelation (EDTA) and dilution, thus excluding direct proteolytic destruction of TF as the mechanism for inhibition. Using crude TF, serum immunodepleted of factor VII, and serum depleted of the vitamin K- dependent coagulation factors by BaSO4 absorption, it is shown that TF factor inhibition requires the presence of VII(a), X(a), and an additional moiety contained in barium-absorbed serum. When each of the other required components were at saturating concentrations, half- maximal inhibition of TF occurred in reaction mixtures containing 2% (vol/vol) of TF at a factor VII(a) concentration of 4 ng/mL (80 pmol/L), a factor X concentration of 50 ng/mL (850 pmol/L), and a concentration of barium-absorbed serum of 2.5% (vol/vol). Catalytically active factor Xa appeared to be required for the generation of optimal TF inhibition. The results are consistent with the conclusions of Hjort that barium-absorbed serum contains a moiety that inhibits the VIIa- Ca2+-TF complex. The role of factor X(a) in the generation of the inhibitory phenomenon remains to be elucidated. The inhibitor present in serum (plasma) may in part be produced by the liver in vivo since cultured human hepatoma cells (HepG2) secrete this inhibitory activity in vitro.

Blocking the Initiation of Coagulation by RNA Aptamers to Factor VIIa

2000 ◽  
Vol 84 (11) ◽  
pp. 841-848 ◽  
Author(s):  
H. Lyerly ◽  
Jeffrey Lawson ◽  
Christopher Rusconi ◽  
Alice Yeh ◽  
Bruce Sullenger
Keyword(s):  
Human Plasma ◽  
Tissue Factor ◽  
In Vitro Selection ◽  
Factor Viia ◽  
Coagulation Factor ◽  
Factor Vii ◽  
Dependent Manner ◽  
Factor X ◽  
Coagulation Factor Vii

SummaryThe tissue factor/factor VIIa complex is thought to be the primary initiator of most physiologic blood coagulation events. Because of its proximal role in this process, we sought to generate new inhibitors of tissue factor/factor VIIa activity by targeting factor VIIa. We employed a combinatorial RNA library and in vitro selection methods to isolate a high affinity, nuclease-resistant RNA ligand that binds specifically to coagulation factor VII/VIIa. This RNA inhibits the tissue factordependent activation of factor X by factor VIIa. Kinetic analyses of the mechanism of action of this RNA suggest that it antagonizes factor VIIa activity by preventing formation of a functional factor VII/tissue factor complex. Furthermore, this RNA significantly prolongs the prothrombin time of human plasma in a dose dependent manner, and has an in vitro half-life of ∼15 h in human plasma. Thus, this RNA ligand represents a novel class of anticoagulant agents directed against factor VIIa.

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