scholarly journals Effects of platelet inhibitors on the platelet aggregation induced by plasma from patients with thrombotic thrombocytopenic purpura

Blood ◽  
1981 ◽  
Vol 58 (2) ◽  
pp. 354-359 ◽  
Author(s):  
EC Lian ◽  
N Savaraj
Keyword(s):  
Platelet Aggregation ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Creatine Phosphate ◽  
Antiplatelet Drugs ◽  
Platelet Inhibitors ◽  
Prostaglandin I2 ◽  
Thrombocytopenic Purpura ◽  
Dextran 70

Abstract Antiplatelet drugs have been used in the treatment of thrombotic thrombocytopenic purpura (TTP) but there in vivo efficacy remains controversial. It has been shown that, in vitro, the plasmas obtained from patients with TTP induced the aggregation of washed platelets from normal donors as well as patients in remission. The effects of platelet inhibitors on the TTP plasma-induced platelet aggregation were examined. It was found that aspirin, indomethacin, ibuprofen, sulfinpyrazone, 5, 8, 11, 14-eisacotetraynoic acid, prostaglandin E1, prostaglandin I2, dBcAMP, apyrase, creatine phosphate/creatine phosphokinase, antimycin, 2-deoxy-D-glucose, dipyridamole, clofibrate, dextran 40, dextran 70, dibucaine, xylocaine, methylmaleimide, and ethylenediamine tetraacetic acid had little or no effect at all. These data lead us to conclude that at least in certain cases, antiplatelet drugs probably play a limited role in the treatment of patients with TTP.

scholarly journals Effects of platelet inhibitors on the platelet aggregation induced by plasma from patients with thrombotic thrombocytopenic purpura

Blood ◽  
1981 ◽  
Vol 58 (2) ◽  
pp. 354-359
Author(s):  
EC Lian ◽  
N Savaraj
Keyword(s):  
Platelet Aggregation ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Creatine Phosphate ◽  
Antiplatelet Drugs ◽  
Platelet Inhibitors ◽  
Prostaglandin I2 ◽  
Thrombocytopenic Purpura ◽  
Dextran 70

Antiplatelet drugs have been used in the treatment of thrombotic thrombocytopenic purpura (TTP) but there in vivo efficacy remains controversial. It has been shown that, in vitro, the plasmas obtained from patients with TTP induced the aggregation of washed platelets from normal donors as well as patients in remission. The effects of platelet inhibitors on the TTP plasma-induced platelet aggregation were examined. It was found that aspirin, indomethacin, ibuprofen, sulfinpyrazone, 5, 8, 11, 14-eisacotetraynoic acid, prostaglandin E1, prostaglandin I2, dBcAMP, apyrase, creatine phosphate/creatine phosphokinase, antimycin, 2-deoxy-D-glucose, dipyridamole, clofibrate, dextran 40, dextran 70, dibucaine, xylocaine, methylmaleimide, and ethylenediamine tetraacetic acid had little or no effect at all. These data lead us to conclude that at least in certain cases, antiplatelet drugs probably play a limited role in the treatment of patients with TTP.

scholarly journals Studies investigating platelet aggregation and release initiated by sera from patients with thrombotic thrombocytopenic purpura

Blood ◽  
1987 ◽  
Vol 69 (3) ◽  
pp. 924-928 ◽  
Author(s):  
JG Kelton ◽  
JC Moore ◽  
WG Murphy
Keyword(s):  
Platelet Aggregation ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Disease Process ◽  
The Other ◽  
Platelet Glycoprotein ◽  
Glycoprotein Ib ◽  
Thrombocytopenic Purpura ◽  
Induced Aggregation

Many patients with thrombotic thrombocytopenic purpura (TTP) have a platelet aggregating factor in their serum that may be pathologically linked with the disease process. To help characterize the type of platelet aggregation and platelet release induced by the sera from seven TTP patients, we measured the ability of a variety of inhibitors of platelet function as well as the ability of monoclonal antibodies (MoAbs) against platelet glycoproteins to inhibit TTP sera-induced platelet aggregation and release. These results were compared with the ability of the same inhibitors to block platelet aggregation induced by ristocetin, collagen, ADP, thrombin, and IgG-immune complexes. Monoclonal antibody directed against platelet glycoprotein Ib totally inhibited ristocetin-induced aggregation and release but had no effect on aggregation and release induced by the TTP sera or by any of the other platelet agonists. However, the MoAb against glycoproteins IIb/IIIa inhibited aggregation and release caused by TTP sera as well as by collagen, thrombin, and ADP but had no effect on aggregation and release induced by ristocetin. The aggregating activity could be abolished by heparin but not by the serine protease inhibitor PMSF (1 mmol/L). And although monomeric human IgG and purified Fc fragments of IgG inhibited IgG-immune complex-induced aggregation and release, they had no effect on TTP sera-induced aggregation and release nor on aggregation and release induced by any of the other agonists. Consistent with these in vitro studies showing no effect of IgG were the in vivo observations that intravenous (IV) IgG was without effect when administered to three patients with TTP. This study indicates that although a von Willebrand factor (vWF)-rich preparation of cryoprecipitate enhances the in vitro platelet aggregation and release caused by sera from the seven TTP patients we studied, the pathway of aggregation and release is not via platelet glycoprotein Ib. Also the aggregating factor of TTP sera is not neutralized in vitro or in vivo by IgG.

scholarly journals Studies investigating platelet aggregation and release initiated by sera from patients with thrombotic thrombocytopenic purpura

Blood ◽  
1987 ◽  
Vol 69 (3) ◽  
pp. 924-928 ◽  
Author(s):  
JG Kelton ◽  
JC Moore ◽  
WG Murphy
Keyword(s):  
Platelet Aggregation ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Disease Process ◽  
The Other ◽  
Platelet Glycoprotein ◽  
Glycoprotein Ib ◽  
Thrombocytopenic Purpura ◽  
Induced Aggregation

Abstract Many patients with thrombotic thrombocytopenic purpura (TTP) have a platelet aggregating factor in their serum that may be pathologically linked with the disease process. To help characterize the type of platelet aggregation and platelet release induced by the sera from seven TTP patients, we measured the ability of a variety of inhibitors of platelet function as well as the ability of monoclonal antibodies (MoAbs) against platelet glycoproteins to inhibit TTP sera-induced platelet aggregation and release. These results were compared with the ability of the same inhibitors to block platelet aggregation induced by ristocetin, collagen, ADP, thrombin, and IgG-immune complexes. Monoclonal antibody directed against platelet glycoprotein Ib totally inhibited ristocetin-induced aggregation and release but had no effect on aggregation and release induced by the TTP sera or by any of the other platelet agonists. However, the MoAb against glycoproteins IIb/IIIa inhibited aggregation and release caused by TTP sera as well as by collagen, thrombin, and ADP but had no effect on aggregation and release induced by ristocetin. The aggregating activity could be abolished by heparin but not by the serine protease inhibitor PMSF (1 mmol/L). And although monomeric human IgG and purified Fc fragments of IgG inhibited IgG-immune complex-induced aggregation and release, they had no effect on TTP sera-induced aggregation and release nor on aggregation and release induced by any of the other agonists. Consistent with these in vitro studies showing no effect of IgG were the in vivo observations that intravenous (IV) IgG was without effect when administered to three patients with TTP. This study indicates that although a von Willebrand factor (vWF)-rich preparation of cryoprecipitate enhances the in vitro platelet aggregation and release caused by sera from the seven TTP patients we studied, the pathway of aggregation and release is not via platelet glycoprotein Ib. Also the aggregating factor of TTP sera is not neutralized in vitro or in vivo by IgG.

Platelet-agglutinating protein P37 from a thrombotic thrombocytopenic purpura plasma forms a complex with human immunoglobulin G

Blood ◽  
1988 ◽  
Vol 71 (2) ◽  
pp. 299-304 ◽  
Author(s):  
FA Siddiqui ◽  
EC Lian
Keyword(s):  
Complex Formation ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Fluid Phase ◽  
Enzyme Linked Immunosorbent Assay ◽  
Thrombocytopenic Purpura ◽  
Form Complex ◽  
Specific Igg ◽  
Sepharose 4B

Abstract We have previously reported the purification of a 37-kd platelet- agglutinating protein (PAP p37) from the plasma of a patient with thrombotic thrombocytopenic purpura (TTP) that was shown to be present in a subset of TTP patients. The platelet agglutination induced by PAP p37 has been shown to be inhibited by IgG from normal human adults and the same TTP patient after recovery. To elucidate the mechanism of inhibition of IgG, the interaction between PAP p37 and IgG was studied. The complex formation was demonstrated by the binding of fluid-phase IgG from normal adults and the same TTP patient after recovery to adsorbed PAP by using an enzyme-linked immunosorbent assay. The binding was specific, concentration dependent, and saturable. IgG purified from a 5-month-old baby and the same TTP patient during active disease did not form complex with PAP p37. The IgG covalently cross-linked to Sepharose 4B bound 125I-PAP p37 but not 125I-fibrinogen. Sucrose density gradient ultracentrifugation of a mixture of 125I-PAP p37 and IgG also revealed the fluid-phase complex formation with a sedimentation value of 19S. Complexes of molecular weight ranging from 180,000 to over 350,000 daltons were also detected by molecular sieve chromatography. The IgG that was bound to PAP p37 conjugated to Sepharose 4B inhibited the agglutination of washed platelets induced by TTP plasma containing PAP p37, whereas the IgG that was not bound to PAP p37 did not have a significant inhibitory effect. The complex formation between PAP p37 and specific IgG is likely to account for the in vitro inhibition of TTP plasma-induced agglutination and, at least partly, the in vivo successful treatment with specific IgG-containing normal plasma.

scholarly journals Calcium-dependent cysteine protease activity in the sera of patients with thrombotic thrombocytopenic purpura

Blood ◽  
1987 ◽  
Vol 70 (5) ◽  
pp. 1683-1687 ◽  
Author(s):  
WG Murphy ◽  
JC Moore ◽  
JG Kelton
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Cysteine Protease ◽  
Platelet Activating Factor ◽  
Aminocaproic Acid ◽  
Human Platelets ◽  
Thrombocytopenic Purpura ◽  
Platelet Surface ◽  
Calcium Dependent

Abstract Plasma and serum from patients with thrombotic thrombocytopenic purpura (TTP) can cause activation and aggregation of normal human platelets in vitro. It is possible that this platelet-activating factor contributes to the disease. In this report we describe studies designed to identify the platelet-activating factor in TTP. Platelet activation by sera from 15 patients with TTP was inhibited by leupeptin, iodoacetamide, and antipain but not by phenylmethylsulphonylfluoride, epsilon-aminocaproic acid, soybean trypsin inhibitor, aprotinin, and D-phenylanyl-1-prolyl-1- arginine chloromethyl ketone. These studies suggested that the platelet- activating factor in TTP serum was a cysteine protease. We confirmed that a calcium-dependent cysteine protease (CDP) was present in the sera of each of the 15 patients when we used an assay based on the ability of CDP to proteolyse platelet membrane glycoprotein 1b (GP1b) and hence to abolish the ability of CDP-treated normal platelets to agglutinate in the presence of ristocetin and von Willebrand factor. This proteolytic activity was inhibited by EDTA, leupeptin, antipain, iodoacetamide, and by N-ethyl-maleamide (NEM) but not by the serine protease inhibitors. Activity was detected in 15 of 15 patients with TTP tested before therapy was begun. In contrast, no activity was detected in the serum of any of five of the TTP patients tested in remission or in any of the sera from 36 patients with thrombocytopenia and 423 nonthrombocytopenic controls. To look for in vivo CDP activity in patients with TTP, we studied platelets from two patients with acute TTP (drawn into acid-citrate-dextrose, NEM, and leupeptin). These platelets showed a loss of GP1b from the platelet surface. Both patients were also studied in remission: GP1b on the platelet surface had returned to normal. These studies provide evidence that CDP is present in the sera of patients with TTP, that it is specific to this disease, and that is is active in vivo as well as in vitro. We postulate that a disorder of CDP homeostasis plays a major role in the pathophysiology of TTP.

scholarly journals Synergistic interactions between interferon-γ and TRAIL modulate c-FLIP in endothelial cells, mediating their lineage-specific sensitivity to thrombotic thrombocytopenic purpura plasma–associated apoptosis

Blood ◽  
2008 ◽  
Vol 112 (2) ◽  
pp. 340-349 ◽  
Author(s):  
Radu Stefanescu ◽  
Dustin Bassett ◽  
Rozbeh Modarresi ◽  
Francisco Santiago ◽  
Mohamad Fakruddin ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Interferon Γ ◽  
Microvascular Endothelial Cell ◽  
Caspase 8 ◽  
Inhibitory Protein ◽  
Thrombocytopenic Purpura ◽  
Ifn Γ ◽  
Interfering Rna

Abstract Microvascular endothelial cell (MVEC) injury coupled to progression of platelet microthrombi facilitated by ADAMTS13 deficiency is characteristic of idiopathic and HIV-linked thrombotic thrombocytopenic purpura (TTP). Cytokines capable of inducing MVEC apoptosis in vitro are up-regulated in both TTP and HIV infection. However, the concentrations of these cytokines required to elicit EC apoptosis in vitro are 2- to 3-log–fold greater than present in patient plasmas. We report that clinically relevant levels of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) and interferon (IFN)–γ act in synergy to induce apoptosis in dermal MVECs, but have no effect on large-vessel ECs or pulmonary MVECs. This reflects the tissue distribution of TTP lesions in vivo. Sensitivity to TTP plasma or TRAIL plus IFN-γ is paralleled by enhanced ubiquitination of the caspase-8 regulator cellular FLICE-like inhibitory protein (c-FLIP), targeting it for proteasome degradation. c-FLIP silencing with anti-FLIP short interfering RNA (siRNA) in pulmonary MVECs rendered them susceptible to TTP plasma– and cytokine-mediated apoptosis, while up-regulation of c-FLIP by gene transfer partially protected dermal MVECs from such injury. TTP plasma–mediated apoptosis appears to involve cytokine-induced acceleration of c-FLIP degradation, sensitizing cells to TRAIL-mediated caspase-8 activation and cell death. Suppression of TRAIL or modulation of immunoproteasome activity may have therapeutic relevance in TTP.

scholarly journals Enhanced proteolysis of plasma von Willebrand factor in thrombotic thrombocytopenic purpura and the hemolytic uremic syndrome

Blood ◽  
1989 ◽  
Vol 74 (3) ◽  
pp. 978-983 ◽  
Author(s):  
PM Mannucci ◽  
R Lombardi ◽  
A Lattuada ◽  
P Ruggenenti ◽  
GL Vigano ◽  
...  
Keyword(s):  
Hemolytic Uremic Syndrome ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Von Willebrand Factor ◽  
Relative Increase ◽  
Thrombocytopenic Purpura ◽  
Uremic Syndrome ◽  
Von Willebrand ◽  
Willebrand Factor

To examine whether enhanced in vivo proteolysis of von Willebrand factor (vWF) would account for the reported loss of larger multimers in acute thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS), we studied eight patients with acute TTP/HUS whose blood samples were collected into an anticoagulant containing a cocktail of protease inhibitors to impede in vitro proteolysis. In all, enhanced proteolytic degradation of vWF was expressed as a relative decrease in the intact 225-Kd subunit of vWF and a relative increase in the 176-Kd fragment. However, instead of the loss of larger forms of normal multimers reported by other investigators, the plasma of all but one of our patients (whether they had TTP or HUS) contained a set of larger than normal (supranormal) multimers. Hence, although proteolytic fragmentation of vWF was enhanced during acute TTP/HUS, this phenomenon was not associated with the loss of larger multimers. In the five patients who survived the acute disease and underwent plasma exchange (three with HUS and two with chronic relapsing TTP), subunits and fragments returned to normal values, and supranormal multimers were no longer detected in plasma. In conclusion, even though vWF proteolysis is enhanced in acute TTP/HUS, it does not lead to loss of larger multimers.

PLATELET AGGLUTINATING PROTEIN P37 FROM A THROMBOTIC THROMBOCYTOPENIC PURPURA PLASMA FORMS A COMPLEX WITH IMMUNOGLOBULIN G

1987 ◽  
Author(s):  
F A Siddigui ◽  
E C -Y Lian
Keyword(s):  
Complex Formation ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Fluid Phase ◽  
Sucrose Density Gradient ◽  
Enzyme Linked Immunosorbent Assay ◽  
Thrombocytopenic Purpura ◽  
Mechanism Of Inhibition ◽  
Phase Complex

A 37-KDa platelet agglutinating protein (PAP p37) from the plasma of a patient with thrombotic thrombocytopenic purpura (TTP), has been shown to be present in a subset of TTP patients. The platelet agglutination induced by PAP p37 has been demonstrated to be inhibited by igG from normal adults. To elucidate the mechanism of inhibition of IgG, the interaction between PAP p37 and IgG was studied. The complex formation was demonstrated by the binding of fluid-phase IgG to adsorbed PAP using enzyme-linked immunosorbent assay. The binding was specific, concentration dependent and saturable. The IgG covalently cross-linked to Sepharose 4B bound 125I-PAP but not to 125I-fibrinogen. Sucrose density gradient ultracentrifugation of a mixture of 125I-PAP and IgG also revealed the fluid phase complex formation with a sedimentation value of 19S. Complexes of molecular weight ranging from 180,000 to over 350,000 daltons were also detected by molecular sieve chromatography. The specific complex formation between PAP p37 and IgG is likely to account for the in vitro inhibition of TTP plasma-induced agglutination and , at least partly, the in vivo successful treatment with IgG-containing normal plasma.

In-vitro and in-vivo consequences of mutations in the von Willebrand factor cleaving protease ADAMTS13 in thrombotic thrombocytopenic purpura

2006 ◽  
Vol 96 (10) ◽  
pp. 454-464 ◽  
Author(s):  
Roberta Donadelli ◽  
Federica Banterla ◽  
Miriam Galbusera ◽  
Cristina Capoferri ◽  
Sara Bucchioni ◽  
...  
Keyword(s):  
Thrombotic Thrombocytopenic Purpura ◽  
Von Willebrand Factor ◽  
Protease Activity ◽  
Mammalian Cells ◽  
Expression System ◽  
Thrombocytopenic Purpura ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryThrombotic thrombocytopenic purpura (TTP) is a disease characterized by microvascular thrombosis, often associated with deficiency of the von Willebrand factor (VWF) cleaving protease ADAMTS13.We investigated the spectrum of ADAMTS13 gene mutations in patients with TTP and congenital ADAMTS13 deficiency to establish the consequences on ADAMTS13 processing and activity. We describe five missense (V88M, G1239V, R1060W, R1123C and R1219W), 1 nonsense (W1016Stop) and 1 insertion (82_83insT) mutations. In two patients no mutation was identified despite undetectable protease activity. Expression in HEK293 mammalian cells (V88M, G1239V, R1123C and R1219W) documented that three missense mutants were not secreted, whereas theV88M was secreted at low levels and with reduced activity. We also provide evidence that impaired secretion of ADAMTS13 mutants observed in vitro translates into severely reduced ADAMTS13 antigen levels in patients in vivo. To evaluate whether the small amounts of mutant protease present in the circulation of patients had VWF cleaving activity, WT and mutant rADAMTS13 were stably expressed in Drosophila S2 cells under the influence of the Drosophila BiP protein signal sequence, which allows protein secretion. Drosophila expression system showed a 40–60% protease activity in the mutants. Several single nucleotide polymorphisms (SNPs) within exons and intron boundaries were found in patients, suggesting that the interplay of SNPs could at least in part account for ADAMTS13 functional abnormalities in patients without mutations. In conclusion, defective secretion and impaired activity of the mutants concur to determine an almost complete deficiency of ADAMTS13 activity in patients with a homozygous or two heterozygous ADAMTS13 mutations.

scholarly journals Solvent/detergent-treated plasma suppresses shear-induced platelet aggregation and prevents episodes of thrombotic thrombocytopenic purpura

Blood ◽  
1994 ◽  
Vol 84 (2) ◽  
pp. 490-497 ◽  
Author(s):  
J Moake ◽  
M Chintagumpala ◽  
N Turner ◽  
P McPherson ◽  
L Nolasco ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Thrombotic Thrombocytopenic Purpura ◽  
Fluid Shear Stress ◽  
Platelet Rich Plasma ◽  
Shear Stresses ◽  
Thrombocytopenic Purpura ◽  
Plasma Infusion ◽  
Normal Plasma ◽  
Induced Aggregation

Abstract Two children with congenital chronic relapsing thrombotic thrombocytopenic purpura (TTP) have episodes every 3 weeks. These relapses can be prevented by the infusion of normal fresh-frozen plasma (FFP) without concurrent plasmapheresis. We conducted a study to determine whether the exposure of normal plasma to agents that inactivate human immunodeficiency virus and other viruses destroys the component necessary for the effective treatment of this type of TTP that requires only plasma infusion to prevent or reverse relapses. Clinical responsiveness and von Willebrand factor (vWF)-mediated fluid shear stress-induced platelet aggregation were evaluated before and after the infusion of 10 mL/kg FFP or solvent [tri(n- butyl)phosphate]/detergent (Triton X-100)-treated plasma (S/D plasma). Platelet aggregation at shear stresses of 90 to 180 dyne/cm2 (similar to those in the partially occluded microcirculation) imposed for 30 seconds was excessive using the citrated platelet-rich plasma of both patients, and was associated with the presence of unusually large vWF forms in patient platelet-poor plasma. Infusion with either FFP or S/D plasma at 3-week intervals caused the platelet count to increase to (or above) normal within 1 week (on 12 of 12 occasions); the disappearance or diminution of unusually large vWF forms within 1 hour (on 6 of 10 occasions studied); and the reversal within 1 to 4 hours of excessive shear-induced platelet aggregation (on 8 of 9 occasions studied). We conclude that a component in normal plasma resistant to S/D treatment is responsible for preventing thrombocytopenia and TTP episodes, and for controlling excessive shear-induced aggregation in these patients. Our results suggest that excessive in vivo platelet aggregation in chronic relapsing TTP and excessive in vitro vWF-mediated shear-induced aggregation may be similar phenomena.

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