scholarly journals Demonstration and mode of action of an inhibitor for activated Hageman factor (factor XIIa) of the intrinsic blood coagulation pathway from Schistosoma mansoni

Blood ◽  
1977 ◽  
Vol 49 (4) ◽  
pp. 619-633
Author(s):  
VC Tsang ◽  
RT Damian
Keyword(s):  
Schistosoma Mansoni ◽  
Anticoagulant Activity ◽  
Factor Xii ◽  
Contact Activation ◽  
Factor Xi ◽  
Heat Stable ◽  
Normal Plasma ◽  
Factor Xiia ◽  
Factor Xia ◽  
Coagulation Pathway

An anticoagulant activity from adult Schistosoma mansoni whole worm homogenate is described. The inhibitor appears to be specific for the contact activation step of the intrinsic pathway. Experiments with both human and mouse plasmas have defined the specificity of the inhibitor as follows: (1) It lengthens the partial thromboplastin time of normal plasma. (2) It has no effect on the prothombin time and Russell's viper venom time of normal plasma. (3) Preactivation of normal plasma by a contact activator such as Celite eliminates essentially all inhibitory activity. (4) The inhibitor appears to be heat stable and can be precipitated by centrifugation above 27,000 g. (5) The inhibitor has no effect on the activation of factor XII by Celite. (6) The activation of factor XI by factor XIIa, however, is inhibited by the schistosomal inhibitor. The above data are consistent with the view that S. mansoni adults possess an anticoagulant that is capable of specifically inhibiting the conversion of factor XI to factor XIa by factor XIIa.

scholarly journals Demonstration and mode of action of an inhibitor for activated Hageman factor (factor XIIa) of the intrinsic blood coagulation pathway from Schistosoma mansoni

Blood ◽  
1977 ◽  
Vol 49 (4) ◽  
pp. 619-633 ◽  
Author(s):  
VC Tsang ◽  
RT Damian
Keyword(s):  
Schistosoma Mansoni ◽  
Anticoagulant Activity ◽  
Factor Xii ◽  
Contact Activation ◽  
Factor Xi ◽  
Heat Stable ◽  
Normal Plasma ◽  
Factor Xiia ◽  
Factor Xia ◽  
Coagulation Pathway

Abstract An anticoagulant activity from adult Schistosoma mansoni whole worm homogenate is described. The inhibitor appears to be specific for the contact activation step of the intrinsic pathway. Experiments with both human and mouse plasmas have defined the specificity of the inhibitor as follows: (1) It lengthens the partial thromboplastin time of normal plasma. (2) It has no effect on the prothombin time and Russell's viper venom time of normal plasma. (3) Preactivation of normal plasma by a contact activator such as Celite eliminates essentially all inhibitory activity. (4) The inhibitor appears to be heat stable and can be precipitated by centrifugation above 27,000 g. (5) The inhibitor has no effect on the activation of factor XII by Celite. (6) The activation of factor XI by factor XIIa, however, is inhibited by the schistosomal inhibitor. The above data are consistent with the view that S. mansoni adults possess an anticoagulant that is capable of specifically inhibiting the conversion of factor XI to factor XIa by factor XIIa.

scholarly journals Mechanism of transient adsorption of fibrinogen from plasma to solid surfaces: role of the contact and fibrinolytic systems

Blood ◽  
1988 ◽  
Vol 71 (4) ◽  
pp. 932-939 ◽  
Author(s):  
JL Brash ◽  
CF Scott ◽  
P ten Hove ◽  
P Wojciechowski ◽  
RW Colman
Keyword(s):  
Solid Surfaces ◽  
Factor Xii ◽  
Contact Activation ◽  
Transient Detection ◽  
Normal Plasma ◽  
Plasma Factor ◽  
Factor Xiia ◽  
Factor Xia ◽  
Specific Proteins

The transient detection of fibrinogen on surfaces has been described (Vroman effect) and high-mol-wt kininogen (HK) has been shown to play a role in this reaction. In this study, we attempted to identify the form of HK responsible for preventing detection of the fibrinogen initially adsorbed from plasma to various artificial surfaces and to determine if other plasma components were involved. We compared 125I-fibrinogen adsorption in the presence of normal plasma to plasma deficient in specific proteins. On all surfaces tested, we found that fibrinogen was displaced from the surface. The extent of displacement was greatly reduced, however, but not eliminated in HK-deficient plasma. Factor XII- deficient plasma also showed reduced fibrinogen displacement. These data indicate that HK can actually displace fibrinogen; however, factor XII, or a factor XII-mediated reaction also appears to be necessary for this displacement to occur. Furthermore, when normal plasma was first subjected to extensive contact activation by dextran sulfate, during which the HK was extensively degraded to components smaller than the light chain (as assessed by Western blotting), we observed greatly reduced displacement of fibrinogen. Extensive contact activation of Factor XI-deficient plasma failed to show low-mol-wt derivatives, however, and displacement of fibrinogen was similar to normal plasma that had not undergone extensive activation. These data indicate that HKa (active cofactor produced during contact activation by factor XIIa or kallikrein) is primarily responsible for displacing fibrinogen, and that HKi (inactive cofactor generated by factor XIa) cannot displace fibrinogen. The fibrinogen from all plasma samples looked similar by Western blot analysis, suggesting that fibrinogenolysis was not a component of the Vroman effect. In addition, experiments performed with plasma prechromatographed on lysine agarose showed that a lysine- agarose adsorbable protein may be minimally involved in fibrinogen desorption and a synergism may exist between HK and that protein.

scholarly journals Mechanism of transient adsorption of fibrinogen from plasma to solid surfaces: role of the contact and fibrinolytic systems

Blood ◽  
1988 ◽  
Vol 71 (4) ◽  
pp. 932-939 ◽  
Author(s):  
JL Brash ◽  
CF Scott ◽  
P ten Hove ◽  
P Wojciechowski ◽  
RW Colman
Keyword(s):  
Solid Surfaces ◽  
Factor Xii ◽  
Contact Activation ◽  
Transient Detection ◽  
Normal Plasma ◽  
Plasma Factor ◽  
Factor Xiia ◽  
Factor Xia ◽  
Specific Proteins

Abstract The transient detection of fibrinogen on surfaces has been described (Vroman effect) and high-mol-wt kininogen (HK) has been shown to play a role in this reaction. In this study, we attempted to identify the form of HK responsible for preventing detection of the fibrinogen initially adsorbed from plasma to various artificial surfaces and to determine if other plasma components were involved. We compared 125I-fibrinogen adsorption in the presence of normal plasma to plasma deficient in specific proteins. On all surfaces tested, we found that fibrinogen was displaced from the surface. The extent of displacement was greatly reduced, however, but not eliminated in HK-deficient plasma. Factor XII- deficient plasma also showed reduced fibrinogen displacement. These data indicate that HK can actually displace fibrinogen; however, factor XII, or a factor XII-mediated reaction also appears to be necessary for this displacement to occur. Furthermore, when normal plasma was first subjected to extensive contact activation by dextran sulfate, during which the HK was extensively degraded to components smaller than the light chain (as assessed by Western blotting), we observed greatly reduced displacement of fibrinogen. Extensive contact activation of Factor XI-deficient plasma failed to show low-mol-wt derivatives, however, and displacement of fibrinogen was similar to normal plasma that had not undergone extensive activation. These data indicate that HKa (active cofactor produced during contact activation by factor XIIa or kallikrein) is primarily responsible for displacing fibrinogen, and that HKi (inactive cofactor generated by factor XIa) cannot displace fibrinogen. The fibrinogen from all plasma samples looked similar by Western blot analysis, suggesting that fibrinogenolysis was not a component of the Vroman effect. In addition, experiments performed with plasma prechromatographed on lysine agarose showed that a lysine- agarose adsorbable protein may be minimally involved in fibrinogen desorption and a synergism may exist between HK and that protein.

scholarly journals A monoclonal anti-human plasma prekallikrein antibody that inhibits activation of prekallikrein by factor XIIa on a surface

Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1053-1062
Author(s):  
D Veloso ◽  
LD Silver ◽  
S Hahn ◽  
RW Colman
Keyword(s):  
Heavy Chain ◽  
Sodium Dodecyl ◽  
Factor Xii ◽  
Contact Activation ◽  
Fab Fragments ◽  
Microtiter Plates ◽  
Normal Plasma ◽  
Reducing Conditions ◽  
Factor Xiia ◽  
Kallikrein Activity

Of five IgGI/k murine monoclonal anti-human prekallikrein antibodies produced (MAbs), MAb 13G11 was selected for studying interaction of prekallikrein with factor XII and high-mol-wt kininogen (HMWK) during activation on a surface. Immunoblots from sodium dodecyl sulfate (SDS) gels showed that this MAb recognizes two variants (88 kd and 85 kd) of prekallikrein and kallikrein both in purified proteins and normal plasma. Under reducing conditions, kallikrein exhibits the epitope on the heavy chain but not on the light chains. Preincubation of MAb 13G11 with prekallikrein (added to prekallikrein-deficient plasma) or with normal plasma inhibited surface activation of prekallikrein 60% to 80%, as judged by amidolytic and coagulant assays. In normal plasma, inhibition by the Fab fragments was 87% of that with the entire MAb. Inhibition was not by competition between the MAb and HMWK, since neither binding of 13G11 to prekallikrein (coated on microtiter plates) was inhibited by an excess of HMWK, nor was hydrolysis of HMWK by kallikrein inhibited by 13G11. Using purified proteins in a system mimicking contact activation, inhibition by 13G11 of prekallikrein activation by factor XIIa, HMWK, and kaolin present was approximately 80%. Decreased inhibition (55% to 25%) occurred without HMWK or when kallikrein was used instead of prekallikrein. Kallikrein activity was not inhibited by 13G11 Fab fragments. These results indicate that the effect of 13G11 in plasma was neither dissociation of prekallikrein- HMWK complex nor a direct effect on kallikrein activity. Similar to the results in plasma, activation of prekallikrein, HMWK present, by factor XIIa bound to kaolin, was inhibited approximately 70% by 13G11. The results suggest a previously unrecognized site on the prekallikrein (heavy chain) required for its interaction with factor XIIa, either shared with the 13G11 epitope or located in very close proximity. The inhibition of kallikrein by intact 13G11 indicates that its binding site on the heavy chain is sterically related to the active site (light chain).

scholarly journals A monoclonal anti-human plasma prekallikrein antibody that inhibits activation of prekallikrein by factor XIIa on a surface

Blood ◽  
1987 ◽  
Vol 70 (4) ◽  
pp. 1053-1062 ◽  
Author(s):  
D Veloso ◽  
LD Silver ◽  
S Hahn ◽  
RW Colman
Keyword(s):  
Heavy Chain ◽  
Sodium Dodecyl ◽  
Factor Xii ◽  
Contact Activation ◽  
Fab Fragments ◽  
Microtiter Plates ◽  
Normal Plasma ◽  
Reducing Conditions ◽  
Factor Xiia ◽  
Kallikrein Activity

Abstract Of five IgGI/k murine monoclonal anti-human prekallikrein antibodies produced (MAbs), MAb 13G11 was selected for studying interaction of prekallikrein with factor XII and high-mol-wt kininogen (HMWK) during activation on a surface. Immunoblots from sodium dodecyl sulfate (SDS) gels showed that this MAb recognizes two variants (88 kd and 85 kd) of prekallikrein and kallikrein both in purified proteins and normal plasma. Under reducing conditions, kallikrein exhibits the epitope on the heavy chain but not on the light chains. Preincubation of MAb 13G11 with prekallikrein (added to prekallikrein-deficient plasma) or with normal plasma inhibited surface activation of prekallikrein 60% to 80%, as judged by amidolytic and coagulant assays. In normal plasma, inhibition by the Fab fragments was 87% of that with the entire MAb. Inhibition was not by competition between the MAb and HMWK, since neither binding of 13G11 to prekallikrein (coated on microtiter plates) was inhibited by an excess of HMWK, nor was hydrolysis of HMWK by kallikrein inhibited by 13G11. Using purified proteins in a system mimicking contact activation, inhibition by 13G11 of prekallikrein activation by factor XIIa, HMWK, and kaolin present was approximately 80%. Decreased inhibition (55% to 25%) occurred without HMWK or when kallikrein was used instead of prekallikrein. Kallikrein activity was not inhibited by 13G11 Fab fragments. These results indicate that the effect of 13G11 in plasma was neither dissociation of prekallikrein- HMWK complex nor a direct effect on kallikrein activity. Similar to the results in plasma, activation of prekallikrein, HMWK present, by factor XIIa bound to kaolin, was inhibited approximately 70% by 13G11. The results suggest a previously unrecognized site on the prekallikrein (heavy chain) required for its interaction with factor XIIa, either shared with the 13G11 epitope or located in very close proximity. The inhibition of kallikrein by intact 13G11 indicates that its binding site on the heavy chain is sterically related to the active site (light chain).

scholarly journals Activation of factor XI in plasma is dependent on factor XII [see comments]

Blood ◽  
1993 ◽  
Vol 81 (3) ◽  
pp. 580-586 ◽  
Author(s):  
T Brunnee ◽  
C La Porta ◽  
SR Reddigari ◽  
VM Salerno ◽  
AP Kaplan ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Dextran Sulfate ◽  
Coagulation Cascade ◽  
Factor Xii ◽  
Factor Xi ◽  
Extrinsic Pathway ◽  
Physiological Relevance ◽  
Factor Xiia ◽  
Kinetics Of ◽  
Coagulation Pathway

The activation of factor XI initiates the intrinsic coagulation pathway. Until recently it was believed that the main activator of factor XI is factor XIIa in conjunction with the cofactor high molecular weight kininogen on a negatively charged surface. Two recent reports have presented evidence that in a purified system factor XI is activatable by thrombin together with the soluble polyanion dextran sulfate. To assess the physiological relevance of these findings we studied the activation of factor XI in normal and factor XII-deficient plasma. We used either kaolin/cephalin or dextran sulfate as a surface for the intrinsic coagulation pathway, tissue factor to generate thrombin via the extrinsic pathway, or the addition of alpha-thrombin directly. 125I-factor XI, added to factor XI-deficient plasma at physiologic concentrations (35 nmol/L), is rapidly cleaved on incubation with kaolin. The kinetics appear to be exponential with half the maximum cleavage at 5 minutes. Similar kinetics of factor XI cleavage are seen when 40 nmol/L factor XIIa (equal to 10% of factor XII activation) is added to factor XII-deficient plasma if an activating surface is provided. Tissue factor (1:500) added to plasma did not induce cleavage of factor XI during a 90-minute incubation, although fibrin formation within 30 seconds indicated that thrombin was generated via the extrinsic pathway. Adding 1 mumol/L alpha-thrombin (equivalent to 50% prothrombin activation) directly to factor XII deficient or normal plasma (with or without kaolin/cephalin/Ca2+ or dextran sulfate) led to instantaneous fibrinogen cleavage, but again no cleavage of factor XI was observable. We conclude that in plasma surroundings factor XI is not activated by thrombin, and that proposals of thrombin initiation of the intrinsic coagulation cascade are not supportable.

scholarly journals Pseudo-factor-XI deficiency: effect of an inhibitor of factor XI adsorption to surface

Blood ◽  
1981 ◽  
Vol 57 (3) ◽  
pp. 437-443
Author(s):  
S Schiffman ◽  
R Margalit ◽  
M Rosove ◽  
D Feinstein
Keyword(s):  
Partial Thromboplastin Time ◽  
Gel Filtration ◽  
Glass Tube ◽  
Factor Xii ◽  
Contact Activation ◽  
Factor Xi ◽  
Factor Xi Deficiency ◽  
Normal Plasma

Recently we have described a normal plasma activity that modulates contact activation by inhibiting adsorption of factor XI to activating surfaces. Here we report the first identified case in which a patient has abnormal clotting tests due to an excess of a similar activity. The patient's plasma had a prolonged partial thromboplastin time and low apparent factor XI assay. His plasma prolonged the partial thromboplastin time of normal plasma and partially neutralized normal factor XI activity in vivo and in vitro. Analysis in dilute plasma revealed normal amounts of factor XI activity and antigen. Factor XI adsorption from plasma to activating surfaces was tested by adding a small amount of 125I-labeled purified factor XI to plasma, exposing the mixture to a glass tube or kaolin, and determining the amount of factor XI adsorbed to the surface. Whereas normal plasma and plasmas deficient in factor XII, factor XI, or Fletcher factor yielded about 4% adsorption to glass, factor XI adsorption from patient's plasma was less than 1%, indicating the presence of an adsorption inhibitor. This inhibitor did not affect factor XI activation or the activity of preformed factor XIa. It was not adsorbed by AI(OH)3 and was present in serum and the macroglobulin peak on gel filtration of the plasma through Sephadex G-200. The patient's history does not allow a definitive conclusion as to whether this inhibitor was associated with abnormal bleeding.

scholarly journals Activation of factor XI in plasma is dependent on factor XII [see comments]

Blood ◽  
1993 ◽  
Vol 81 (3) ◽  
pp. 580-586 ◽  
Author(s):  
T Brunnee ◽  
C La Porta ◽  
SR Reddigari ◽  
VM Salerno ◽  
AP Kaplan ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Dextran Sulfate ◽  
Coagulation Cascade ◽  
Factor Xii ◽  
Factor Xi ◽  
Extrinsic Pathway ◽  
Physiological Relevance ◽  
Factor Xiia ◽  
Kinetics Of ◽  
Coagulation Pathway

Abstract The activation of factor XI initiates the intrinsic coagulation pathway. Until recently it was believed that the main activator of factor XI is factor XIIa in conjunction with the cofactor high molecular weight kininogen on a negatively charged surface. Two recent reports have presented evidence that in a purified system factor XI is activatable by thrombin together with the soluble polyanion dextran sulfate. To assess the physiological relevance of these findings we studied the activation of factor XI in normal and factor XII-deficient plasma. We used either kaolin/cephalin or dextran sulfate as a surface for the intrinsic coagulation pathway, tissue factor to generate thrombin via the extrinsic pathway, or the addition of alpha-thrombin directly. 125I-factor XI, added to factor XI-deficient plasma at physiologic concentrations (35 nmol/L), is rapidly cleaved on incubation with kaolin. The kinetics appear to be exponential with half the maximum cleavage at 5 minutes. Similar kinetics of factor XI cleavage are seen when 40 nmol/L factor XIIa (equal to 10% of factor XII activation) is added to factor XII-deficient plasma if an activating surface is provided. Tissue factor (1:500) added to plasma did not induce cleavage of factor XI during a 90-minute incubation, although fibrin formation within 30 seconds indicated that thrombin was generated via the extrinsic pathway. Adding 1 mumol/L alpha-thrombin (equivalent to 50% prothrombin activation) directly to factor XII deficient or normal plasma (with or without kaolin/cephalin/Ca2+ or dextran sulfate) led to instantaneous fibrinogen cleavage, but again no cleavage of factor XI was observable. We conclude that in plasma surroundings factor XI is not activated by thrombin, and that proposals of thrombin initiation of the intrinsic coagulation cascade are not supportable.

scholarly journals The contact activation mechanism in human plasma: activation induced by dextran sulfate

Blood ◽  
1982 ◽  
Vol 59 (6) ◽  
pp. 1225-1233 ◽  
Author(s):  
F van der Graaf ◽  
FJ Keus ◽  
RA Vlooswijk ◽  
BN Bouma
Keyword(s):  
Human Plasma ◽  
Dextran Sulfate ◽  
Activation Mechanism ◽  
Factor Xii ◽  
Contact Activation ◽  
Prolonged Incubation ◽  
Normal Plasma ◽  
Essential Components ◽  
Factor Xiia ◽  
Kallikrein Activity

Abstract Incubation of normal human plasma with dextran sulfate for 7 min at 4 degrees C generates kallikrein amidolytic activity. No kallikrein activity is generated in factor XII or prekallikrein-deficient plasma and only small amounts (8%) in high molecular weight (HMW) kininogen- deficient plasma. Addition of specific antisera directed against prekallikrein or HMW kininogen to normal plasma blocked the generation of kallikrein activity by dextran sulfate. Thus, factor XII, prekallikrein, and HMW kininogen are essential components for optimal activation of prekallikrein. The role of limited proteolysis in the activation of prekallikrein induced by dextran sulfate was studied by adding 125I-prekallikrein to plasma. The generation of kallikrein activity paralleled the proteolytic cleavage of prekallikrein as judged on SDS gels in the presence of reducing agents. The same cleavage fragments were observed as obtained by activation of purified prekallikrein by beta-factor-XIIa. Addition of 131I-HMW kininogen and 125I-factor XII or 131I-HMW kininogen and 125I-prekallikrein to normal plasma followed by activation with dextran sulfate and analysis on SDS gels indicated that the observed cleavage of prekallikrein and HMW kininogen is fast compared to the observed cleavage of factor XII, which is much slower and less extensive. During the first minutes of incubation of normal plasma with dextran sulfate, mainly alpha-factor- XIIa is formed. During prolonged incubation, beta-factor-XIIa is also formed.

Pseudo-factor-XI deficiency: effect of an inhibitor of factor XI adsorption to surface

Blood ◽  
1981 ◽  
Vol 57 (3) ◽  
pp. 437-443 ◽  
Author(s):  
S Schiffman ◽  
R Margalit ◽  
M Rosove ◽  
D Feinstein
Keyword(s):  
Partial Thromboplastin Time ◽  
Gel Filtration ◽  
Glass Tube ◽  
Factor Xii ◽  
Contact Activation ◽  
Factor Xi ◽  
Factor Xi Deficiency ◽  
Normal Plasma

Abstract Recently we have described a normal plasma activity that modulates contact activation by inhibiting adsorption of factor XI to activating surfaces. Here we report the first identified case in which a patient has abnormal clotting tests due to an excess of a similar activity. The patient's plasma had a prolonged partial thromboplastin time and low apparent factor XI assay. His plasma prolonged the partial thromboplastin time of normal plasma and partially neutralized normal factor XI activity in vivo and in vitro. Analysis in dilute plasma revealed normal amounts of factor XI activity and antigen. Factor XI adsorption from plasma to activating surfaces was tested by adding a small amount of 125I-labeled purified factor XI to plasma, exposing the mixture to a glass tube or kaolin, and determining the amount of factor XI adsorbed to the surface. Whereas normal plasma and plasmas deficient in factor XII, factor XI, or Fletcher factor yielded about 4% adsorption to glass, factor XI adsorption from patient's plasma was less than 1%, indicating the presence of an adsorption inhibitor. This inhibitor did not affect factor XI activation or the activity of preformed factor XIa. It was not adsorbed by AI(OH)3 and was present in serum and the macroglobulin peak on gel filtration of the plasma through Sephadex G-200. The patient's history does not allow a definitive conclusion as to whether this inhibitor was associated with abnormal bleeding.

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