Prostacyclin stability in thrombotic thrombocytopenic purpura. Japan Working Group on TTP

We investigated changes in prostacyclin stabilization activity of the plasma of 13 patients with TTP, by measurement of PGI2 inhibitory activity attenuation on normal platelet aggregation, induced by ADP (4 x 10(-5)M). PGI2 stabilizing activity of plasma was expressed as the half life (half time) in the time course of attenuation of the inhibitory effect of PGI2 on platelet aggregation. The half time was 16.7 +/- 5.8 min in the plasma of 10 healthy subjects. The half time in 10 plasma samples from patients in the acute state of TTP was significantly (p < 0.05) shorter than that of normal plasma. The half time become longer in 8 plasma samples after plasma exchange and increased to normal plasma level, in remission. There was no relationship between the concentration of plasma lipoprotein A1 and the half time of PGI2 stabization activity of plasma.     

Ticlopidine-induced thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) occurs in association with a wide variety of disorders including infections, connective tissue diseases, and solid organ tumors. It also may coincide with administration of drugs such as mitomycin, metronidazole, oral contraceptives, cyclosporine, and many others. We report the occurrence of TTP in a patient shortly after the initiation of ticlopidine.     

8 cases of thrombotic thrombocytopenic purpura]

Eight cases of the thrombocytopenic thrombosis are presented. Etiological factors, prognosis, and actual therapy are discussed. An emphasis is on the significance of freshly frozen plasma administration in the treatment of this disease.     

The varying faces of thrombotic thrombocytopenic purpura

We report a 3-year-old girl with fetal hydantoin syndrome (FHS) whose mother had received phenytoin 600 mg/day throughout gestation. She had growth retardation, mental deficiency, craniofacial dysmorphism and iris colomobata specific to FHS. However, the patient did not have the distal phalangeal hypoplasia which is associated with FHS; instead, she had polydactyly of the right foot. This seems to be the first FHS case in the literature with polydactyly.     

Treatment of thrombotic thrombocytopenic purpura with high-dose immunoglobulins. Results in 17 patients. Italian Cooperative Group for TTP

BACKGROUND: The experimental observation that plasma from TTP patients sometimes exhibits a protein which can cause platelet agglutination, and that such agglutination can be inhibited in vitro by the use of IgG led some authors to treat plasma exchange-resistant TTP patients with high-dose IgG (HDIgG). METHODS: We report the results obtained with HDIgG treatment in 17 patients retrospectively examined by the Italian Cooperative Group for the study of TTP: 6 males and 11 females, mean age was 31.7 years for the women (range: 20-65) and 44.6 for the men (range: 26-66). In all cases HDIgG administration was combined with other treatment modalities. RESULTS: Of the 17 patients, 7 died from disease progression (41.1%), 2 achieved partial remission (11.7%) and the remaining 8 achieved complete remission (47%). Of the 10 cases (58.8%) with a positive response, only in 4 did the addition of HDIgG seem to produce significant improvement. All efforts made to characterize the subgroup of patients who responded to HDIgG and compare them with the non responders failed. CONCLUSIONS: Although our results do not unquestionably demonstrate the role of HDIgG in the treatment of TTP, they suggest a possible role for HDIgG in the treatment of those rare plasma exchange-resistant TTP cases.     

Cytokines in childhood hemolytic uremic syndrome and thrombotic thrombocytopenic purpura

Serum and urine cytokines were analyzed in children with hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). Interleukin-6 (IL-6) was elevated in the serum of 33 of 35 children with HUS (94%) and in 2 of 2 children with recurrent TTP. Serum IL-6 was higher in children with HUS who developed anuria, extrarenal manifestations during the acute phase of illness and/or chronic renal sequelae. Tumor necrosis factor-alpha (TNF-alpha) was detected in the serum of 7 patients with HUS (20%) and 1 patient with TTP. IL-6 and TNF-alpha were elevated in the urine of 4 of 4 children with HUS and 2 of 2 children with TTP. Urinary levels were higher than serum levels, suggesting local production of cytokines in the urinary tract. Sequential serum and urine samples showed that IL-6 levels varied with disease activity. IL-6 and TNF-alpha were not detected in the serum (n = 25) and urine (n = 15) of healthy children. We conclude that IL-6 in urine may be used to monitor disease activity in HUS and TTP.     

Recurrent acute scleroderma renal crisis complicated by thrombotic thrombocytopenic purpura

Acute renal crisis as an early manifestation of scleroderma is underemphasized, and its recurrence after initial successful therapy is rare. We describe a 32-year-old woman who presented with scleroderma renal crisis. A second episode of apparent renal crisis, however, was complicated by thrombotic thrombocytopenic purpura, which led to pancreatitis, a large cerebral infarction, and fatal outcome despite intensive therapy. This case illustrates the complexity and severity of diffuse systemic sclerosis presenting with multiple, major organ complications.     

Antibodies to von Willebrand factor-cleaving protease in acute thrombotic thrombocytopenic purpura

BACKGROUND: Thrombotic thrombocytopenic purpura is a potentially fatal disease characterized by widespread platelet thrombi in the microcirculation. In the normal circulation, von Willebrand factor is cleaved by a plasma protease. We explored the hypothesis that a deficiency of this protease predisposes patients with thrombotic thrombocytopenic purpura to platelet thrombosis. METHODS: We studied the activity of von Willebrand factor-cleaving protease and sought inhibitors of this protease in plasma from patients with acute thrombotic thrombocytopenic purpura, patients with other diseases, and normal control subjects. We also investigated the effect of shear stress on the ristocetin cofactor activity of purified von Willebrand factor in the cryosupernatant fraction of the plasma samples. RESULTS: Thirty-nine samples of plasma from 37 patients with acute thrombotic thrombocytopenic purpura had severe deficiency of von Willebrand factor-cleaving protease. No deficiency was detected in 16 samples of plasma from patients with thrombotic thrombocytopenic purpura in remission or in 74 plasma samples from normal subjects, randomly selected hospitalized patients or outpatients, or patients with hemolysis, thrombocytopenia, or thrombosis from other causes. Inhibitory activity against the protease was detected in 26 of the 39 plasma samples (67 percent) obtained during the acute phase of the disease. The inhibitors were IgG antibodies. Shear stress increased the ristocetin cofactor activity of von Willebrand factor in the cryosupernatant of plasma samples obtained during the acute phase, but decreased the activity in cryosupernatant of plasma from normal subjects. CONCLUSIONS: Inhibitory antibodies against von Willebrand factor-cleaving protease occur in patients with acute thrombotic thrombocytopenic purpura. A deficiency of this protease is likely to have a critical role in the pathogenesis of platelet thrombosis in this disease.     

Renal transplantation in adults with thrombotic thrombocytopenic purpura/haemolytic-uraemic syndrome

BACKGROUND: Thrombotic thrombocytopenic purpura/haemolytic-uraemic syndrome (TTP/HUS) is a rare cause of renal failure in adults. There is little data concerning the outcome of adult patients who receive a renal transplant for TTP/HUS: METHODS: We have carried out a survey of 22 transplant centres in the USA to determine the outcome of patients who developed ESRD from TTP/HUS and latter received a renal transplant. RESULTS: Twelve of the 22 centres responded to our inquiry. Seven centres had not transplanted any patients with TTP/HUS, and five centres had transplanted a total of 24 grafts in 17 patients with TTP/HUS: Thirty-three per cent of patients demonstrated definite clinical and pathological evidence of recurrence of TTP/HUS: An additional 16% of patients demonstrated pathological evidence of possible recurrence of TTP/HUS in the absence of clinical manifestations. The overall 1-year graft survival rate was 42% and the 2-year graft survival rate was 35%. In our experience recurrence TTP/HUS was associated with universal graft failure. Although cyclosporin A does occasionally cause a thrombotic angiopathy in patients with no history of TTP/HUS, we found no evidence that it should be avoided in patients with a previous history of ESRD from TTP/HUS who subsequently receive a renal transplant. CONCLUSIONS: TTP/HUS frequently recurres in adults who receive a renal transplant, with a 2-year graft survival rate of 35%.     

Acute pancreatitis as a triggering factor for thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) constitutes a poorly understood multisystemic disease of vascular origin that may involve any organ by thrombotic occlusions of the small vessels. Treatment with plasmapheresis is the best therapeutic option at this present moment. Involvement of the pancreas is a well established feature of this disease, which has generally been interpreted as a consequence of pancreatic vascular compromise. However, there are a few cases in the literature in which the clinical signs of TTP developed well after the clinical and laboratory demonstration of acute pancreatitis (AP). Therefore, the possibility of pancreatic inflammation as a triggering factor of TTP may need to be considered. This cause-effect relationship between AP and TTP remains unclear. We report a patient with chronic pancreatitis presenting with two episodes of TTP, triggered by acute relapses of pancreatitis. TTP may, thus, constitute a hematological complication of AP. We discuss the pathophysiological aspects of this association, along with therapeutical options.     

Increased serum levels of thrombopoietin in patients with thrombotic thrombocytopenic purpura, idiopathic thrombocytopenic purpura, or disseminated intravascular coagulation

The serum levels of thrombopoietin (TPO) were measured in 16 patients with thrombotic thrombocytopenic purpura (TTP), 12 with hemolytic uremic syndrome (HUS), 10 with aplastic anemia (AA), 10 with disseminated intravascular coagulation (DIC), and 71 with idiopathic thrombocytopenic purpura (ITP). The serum TPO levels were measured with a sensitive sandwich enzyme-linked immunosorbent assay. The serum TPO level in the ITP group (1.68 +/- 0.85 fmol/ml) were not significantly increased compared with those of the normal subjects. The TPO levels in the TTP (2.77 +/- 1.38 fmol/ml) and HUS groups (5.77 +/- 4.41 fmol/ml) were higher than those of the normal subjects. The patients with AA (12.7 +/- 8.0 fmol/ml) and those with DIC (13.3 +/- 5.7 mol/ml) had significantly higher serum TPO levels than did the normal subjects and ITP patients. The TPO levels were well correlated with the platelet counts in the TTP patients, and were negatively correlated with the platelet counts in the ITP patients. These results suggest that the serum TPO levels in some thrombocytopenic diseases are regulated not only by the platelet count and the megakaryocyte mass, but also by other factors.     

von Willebrand factor-cleaving protease in thrombotic thrombocytopenic purpura and the hemolytic-uremic syndrome

BACKGROUND: Thrombotic thrombocytopenic purpura and the hemolytic-uremic syndrome are severe microvascular disorders of platelet clumping with similar signs and symptoms. Unusually large multimers of von Willebrand factor, capable of agglutinating circulating platelets under high shear stress, occur in the two conditions. We investigated the prevalence of von Willebrand factor-cleaving protease deficiency in patients with familial and nonfamilial forms of these disorders. METHODS: Plasma samples were obtained from 53 patients with thrombotic thrombocytopenic purpura or hemolytic-uremic syndrome. Von Willebrand factor-cleaving protease was assayed in diluted plasma samples with purified normal von Willebrand factor as the substrate. The extent of the degradation of von Willebrand factor was assessed by electrophoresis in sodium dodecyl sulfate-agarose gels and immunoblotting. To determine whether an inhibitor of von Willebrand factor-cleaving protease was present, we measured the protease activity in normal plasma after incubation with plasma from the patients. RESULTS: We examined 30 patients with thrombotic thrombocytopenic purpura and 23 patients with the hemolytic-uremic syndrome. Of 24 patients with nonfamilial thrombotic thrombocytopenic purpura, 20 had severe and 4 had moderate protease deficiency during an acute event. An inhibitor found in 20 of these patients was shown to be IgG in five of five tested plasma samples. Of 13 patients with nonfamilial hemolytic-uremic syndrome, 11 had normal levels of activity of von Willebrand factor-cleaving protease during the acute episode, whereas in 2 patients, the activity was slightly decreased. All 6 patients with familial thrombotic thrombocytopenic purpura lacked von Willebrand factor-cleaving protease activity but had no inhibitor, whereas all 10 patients with familial hemolytic-uremic syndrome had normal protease activity. In vitro proteolytic degradation of von Willebrand factor by the protease was studied in 5 patients with familial and 7 patients with nonfamilial hemolytic-uremic syndrome and was normal in all 12 patients. CONCLUSIONS: Nonfamilial thrombotic thrombocytopenic purpura is due to an inhibitor of von Willebrand factor-cleaving protease, whereas the familial form seems to be caused by a constitutional deficiency of the protease. Patients with the hemolyticuremic syndrome do not have a deficiency of von Willebrand factor-cleaving protease or a defect in von Willebrand factor that leads to its resistance to protease.     

Deficient activity of von Willebrand factor-cleaving protease in chronic relapsing thrombotic thrombocytopenic purpura

In patients with thrombotic thrombocytopenic purpura (TTP), excessive intravascular platelet aggregation has been associated with appearance in plasma of unusually large von Willebrand factor (vWF) multimers. These extremely adhesive vWF multimers may arise due to deficiency of a "depolymerase" cleaving vWF to smaller molecular forms, either by reducing the interdimeric disulfide bridges or by proteolytic degradation. We studied the activity of a recently described vWF-cleaving protease in four patients with chronic relapsing TTP. Diluted plasma samples of TTP patients were incubated with purified normal human vWF in the presence of a serine protease inhibitor, at low ionic strength, and in the presence of urea and barium ions. The extent of vWF degradation was assayed by electrophoresis in sodium dodecyl sulfate-agarose gels and immunoblotting. Four patients, that included two brothers, with chronic relapsing TTP displayed either substantially reduced levels or a complete absence of vWF-cleaving protease activity. In none of these patient plasmas was an inhibitor of or an antibody against the vWF-cleaving protease established. Our data suggest that the unusually large vWF multimers found in TTP patients may be caused by deficient vWF-cleaving protease activity. Deficiency of this protease may be inherited in an autosomal recessive manner and seems to predispose to chronic relapsing TTP. The assay of the vWF-cleaving protease activity may be used as a sensitive diagnostic tool for identification of subjects with a latent TTP tendency.     

Enhanced endothelial cell apoptosis in splenic tissues of patients with thrombotic thrombocytopenic purpura

Idiopathic thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy of obscure etiology. The fundamental pathologic lesion is a hyaline thrombus composed of platelets and some fibrin accompanied by endothelial cell proliferation and detachment, in the absence of an inflammatory response. We have previously demonstrated that plasmas from patients with both idiopathic TTP and a related disorder, sporadic hemolytic-uremic syndrome (HUS), induce apoptosis and expression of the apoptosis-associated molecule Fas (CD95) in vitro in those lineages of microvascular endothelial cells (MVECs) that are affected pathologically. We now demonstrate the presence of enhanced MVEC apoptosis in splenic tissues from patients with TTP, documented by terminal deoxynucleotidyl-transferase-mediated dUTP nick-end labeling (TUNEL) and morphology. This is accompanied by elevated Fas expression. It contrasts with the absence of apoptosis in splenic tissues obtained after splenectomy for trauma or immune thrombocytopenic purpura. TUNEL-positive cells, identified by immunohistochemistry as MVECs or macrophages, presumably engulfing apoptotic ECs, are noted in numerous areas, including those apart from microthrombi. Thus, it is unlikely that EC apoptosis is simply a sequela of thrombus formation. Based on these data, we propose that MVEC apoptosis is of pathophysiologic significance in idiopathic TTP/sporadic HUS.     

The use of plasma as a replacement fluid in plasma exchange. Canadian Apheresis Group

BACKGROUND: The Canadian Apheresis Group has maintained a national registry of apheresis activities for the past 16 years. Since 1991, the use of plasma as a replacement fluid in plasma exchange has been recorded. STUDY DESIGN AND METHODS: Six years of data from the registry on the use of plasma as a replacement fluid were analyzed. RESULTS: Plasma was used in more than 25 percent of all plasma exchange procedures. Of 41,519 plasma exchange procedures reported, 11,970 used plasma alone or in combination with albumin. In 1991, 1026 (78%) of these procedures used plasma appropriately for either thrombotic thrombocytopenic purpura (TTP) or adult hemolytic uremic syndrome (HUS); between 1992 and 1996, these numbers were 1043 (81%), 1570 (86%), 1171 (87%), 2192 (92%), and 2741 (90%), respectively. In the remaining procedures, frozen or cryosupernatant plasma was administered to 326 patients for a total of 40 diseases other than TTP or HUS. CONCLUSIONS: In those diseases for which plasma was administered as the sole replacement fluid, no disease appears to justify such treatment without the existence of an associated condition requiring specific replenishment of some plasma component. Further evaluation of the specific indications for the use of plasma as a replacement fluid in plasma exchange is required for diseases other than TTP or HUS.