7 Thrombotic Thrombocytopenic Purpura and the Haemolytic-Uraemic Syndrome: Evolving Concepts of Pathogenesis and Therapy

Thrombotic thrombocytopenic purpura: A rare complication of acute pancreatitis

Thrombotic Thrombocytopenic Purpura (TTP) is a poorly understood entity involving multiple organs and having grave prognosis if not treated promptly. Acute pancreatitis (AP) is a rare cause of TTP and TTP is also a rare complication of acute pancreatitis. TTP is induced in AP by poorly understood mechanism, which involves multiple pathways apart from only ADAMTS13 deficiency. Here, we report a case of a 32‐year‐old male who developed acute pancreatitis due to chronic alcoholism. He developed signs of TTP from Day 4 of his onset of pain. High clinical suspicion and prompt initiation of plasmapheresis was associated with good outcome. In this case report, we have discussed details of our case and the different mechanisms involved in pathogenesis of TTP in AP and their outcome with prompt management.

[Hemolytic uremic syndrome in adults]

Hemolytic uremic syndrome (HUS) is related to a renal thrombotic microangiopathy, inducing hypertension and acute renal failure (ARF). Its pathogenesis involves an activation/lesion of microvascular endothelial cells, mainly in the renal vasculature, secondary to bacterial toxins, drugs, or autoantibodies. An overactivation of the complement alternate pathway secondary to a heterozygote deficiency of regulatory proteins (factor H, factor I or MCP) or to an activating mutation of factor B or C3 can also result in HUS. Less frequently, renal microthrombi are due to an acquired or a constitutional deficiency in ADAMTS-13, the protease cleaving von Wilebrand factor. Hemolytic anemia with schistocytes, thrombocytopenia without evidence of disseminated intravascular coagulation, and renal failure are consistently found. In typical HUS, a prodromal diarrhea, with blood in the stools, is observed, related to pathogenic enterobacteria, most frequently E. Coli O157:H7. HUS may also occur in the post partum period, and is then related to a factor H or factor I deficiency. HUS may also occur after various treatments such as mitomycin C, gemcitabine, ciclosporin A, or tacrolimus, and as reported more recently bevacizumab, an anti VEGF antibody. Atypical HUS are not associated with diarrhea, may be sporadic or familial, and can be related to an overactivation of the complement alternate pathway. More recently, some of them have been related to a mutation of thrombomodulin, which also regulates the alternate pathway of complement. In adults, several HUS are encountered in the course of chronic nephropathies: nephroangiosclerosis, chronic glomerulonephritis, post irradiation nephropathy, scleroderma, disseminated lupus erythematosus, antiphospholipid syndrome. Overall the prognosis of HUS has improved, with a patient survival greater than 85% at 1 year. Chronic renal failure is observed as a sequella in 20 to 65% of the cases. Plasma infusions and plasma exchanges are effective in most of the cases to treat hemolysis and thrombocytopenia. Steroid therapy is debated, as well as immunosuppressive drugs, including rituximab, in autoimmune forms. A new monoclonal anti-C5 antibody is tested, and seems to be effective in atypical HUS with abnormal complement alternate pathway activation. If terminal renal failure occurs, renal transplantation can be performed but the risk of recurrence, which very low in post infectious forms of HUS, is about 70 to 80% in genetic forms of complement regulatory protein deficiency.

A comparison of thrombotic thrombocytopenic purpura in an inception cohort of patients with and without systemic lupus erythematosus

OBJECTIVES

To compare the clinical presentation, response to therapy and outcome of thrombotic thrombocytopenic purpura (TTP) in an inception cohort of patients with and without SLE.

METHODS

Medical records of patients diagnosed with TTP at Singapore General Hospital between January 2003 and December 2007 were reviewed.

RESULTS

Ten idiopathic TTP (iTTP) and eight SLE-associated TTP (sTTP) patients were identified, with iTTP patients being older (mean 50.4 vs 34.5 yrs). Five iTTP patients were ANA positive but did not have any features of SLE. All sTTP patients had active SLE at TTP diagnosis and had more renal involvement than iTTP (87.5% vs 50%). The mean duration from the first symptom suggestive of TTP to diagnosis was 7.7 days and 19.5 days in iTTP and sTTP patients. All patients received high-dose corticosteroids. Cytotoxic and immunosuppressive drugs were used more commonly (87.5% vs 50%) and earlier (Day 2/3 vs after Day 7) in sTTP patients. Vincristine was the drug of choice in iTTP and cyclophosphamide in sTTP. Three SLE patients received rituximab. Mortality for iTTP and sTTP was 50% (95% CI 19%, 81%) and 62.5% (95% CI 29%, 96%), respectively. The mean (s.d.) time to complete remission was 31.3 (+/- 26.4) days in sTTP (n = 3) and 16.8 (+/- 6.1) days in iTTP (n = 5).

CONCLUSION

Despite early and more aggressive therapy in sTTP, mortality was higher and the time to complete remission were longer, suggesting that sTTP is more severe. The tempo of development of TTP in SLE patients was slower.

Journey in reverse: TTP from bedside to blood bank to bench

Thrombotic thrombocytopenic purpura (TTP) is the most extensive and dangerous intravascular platelet clumping disorder. For more than a half-century after its initial recognition, mortality was near 100% and the etiology totally obscure. Then, in the late 1970s to early 1980s, empiric, but successful, therapy by a few clinician/blood bank partnerships was followed by sudden laboratory insight into pathophysiology. The discussion that follows was prepared in conjunction with the 2006 Francis Morrison, M.D., Memorial Lecture at the 27th Annual Meeting of the American Society for Apheresis.

Thrombotic Thrombocytopenic Purpura: aetiology, pathophysiology and treatment

Thrombotic thrombocytopenic purpura (TTP) is a rare disorder whose varied clinical manifestations result from the formation of platelet-rich thrombi within the microvasculature and consequent tissue ischaemia. This review will outline how, in the eighty years since its initial description, scientific discoveries have not only led to a deeper understanding of the fundamental pathophysiology of TTP, but have also contributed to advances in the clinical management of this condition. Current research in this field will hopefully provide the basis for the design and development of novel therapeutic strategies.

Thrombotic thrombocytopenic purpura in patients with retroviral infection is highly responsive to plasma infusion therapy

We prospectively studied presentation biological differences and the response to therapy in patients with thrombotic thrombocytopenic purpura (TTP) associated with, or unrelated to human immunodeficiency virus (HIV) infection. TTP patients underwent standard evaluations and were treated with prednisone 1 mg/kg in addition to infusions of fresh frozen plasma (FFP; 30 ml/kg/d) until normalization of the platelet count. Unresponsive patients were referred for plasma exchange. Compared with HIV- TTP patients (n=23), in HIV+ subjects (n=21) microangiopathy was dominant among Black females, who had lower presentation Hb (median 5.8 g/dl; P=0.03), platelet count (13 x 10(9)/l; P=0.05) and a CD4 count of 0.096 x 10(9)/l. HIV+ individuals responded to FFP faster than HIV- patients and none of them required apheresis. Ten HIV- TTP patients required apheresis (P=0.03) and four died. Responses in the HIV+ and HIV- groups occurred after treatment with a median of 33 and 55 units (one unit=320 ml) of FFP (P=0.004) respectively. Response to this protocol was seen in 84% (95% response in HIV+ patients). Regression analysis showed that survival was associated with younger age (P=0.001), rapid platelet (P=0.001) and Hb (P=0.0009) recovery, and fewer FFP units to normal lactate dehydrogenase levels (P=0.006). We conclude that in HIV+ individuals, microangiopathy is highly responsive to plasma infusions. This observation is important particularly when apheresis is not available.

Thrombotic thrombocytopenic purpura: 24 years of experience at the American University of Beirut Medical Center

Thrombotic thrombocytopenic purpura (TTP) is a hematological syndrome defined by the presence of thrombocytopenia and microangiopathic hemolytic anemia without a clinically apparent etiology. Patients may also suffer from fever in addition to neurological and renal impairment. Treatment should be initiated as soon as possible, otherwise this rare disease can be fatal. The main treatment options include therapeutic plasma exchange, fresh frozen plasma infusion, and adjuvant agents such as steroids and antiplatelet drugs. A search of patient records was carried out at the American University of Beirut Medical Center looking for patients who developed TTP over a 24-year period extending from 1980 to 2003. Relevant information was collected and analyzed. A total of 47 records were found. All presented with anemia and thrombocytopenia, 83% had neurological symptoms, 61.7% had fever and 34% had renal impairment. All patients were treated with a multimodality regimen including therapeutic plasma exchange, FFP infusion, steroids, antiplatelet agents, vincristine and others. 38 (81%) cases achieved complete remission. Out of these, 12 (31.6%) relapsed and responded to treatment. Patients who did not receive plasma exchange were more likely to relapse (P = 0.032). A second relapse was observed in 6 cases. The overall mortality rate from TTP over 24 years was 21.3%. TTP remains a fatal disease. A high index of suspicion should, therefore, always be present. Treatment options should be further developed and patients should directly be referred to tertiary care centers.

von Willebrand factor, ADAMTS-13, and thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a severe, occlusive, microvascular "thrombotic microangiopathy" characterized by systemic platelet aggregation, organ ischemia, profound thrombocytopenia, and erythrocyte fragmentation. Failure to degrade "unusually large" (UL) von Willebrand factor (VWF) multimers as they are secreted from endothelial cells probably causes most cases of familial TTP, acquired idiopathic TTP, thienopyridine-related TTP, and pregnancy-associated TTP. The emphasis in this review is the pathophysiology of familial and acquired idiopathic TTP. In each of these entities, there is a severe defect in the function of a plasma enzyme, VWF-cleaving metalloprotease (ADAMTS-13), that normally cleaves hyper-reactive ULVWF multimers into smaller and less adhesive VWF forms. In familial TTP, mutations in the ADAMTS13 gene cause absent or severely reduced plasma VWF-cleaving metalloprotease activity. Acquired idiopathic TTP, in contrast, is the result in many patients of the production of autoantibodies that inhibit the function of ADAMTS-13. Established, evolving, and some of the unresolved issues in TTP pathophysiology will be summarized.

Acid resistance systems required for survival of Escherichia coli O157:H7 in the bovine gastrointestinal tract and in apple cider are different

Escherichia coli O157:H7 is a highly acid-resistant food-borne pathogen that survives in the bovine and human gastrointestinal tracts and in acidic foods such as apple cider. This property is thought to contribute to the low infectious dose of the organism. Three acid resistance (AR) systems are expressed in stationary-phase cells. AR system 1 is sigma(S) dependent, while AR systems 2 and 3 are glutamate and arginine dependent, respectively. In this study, we sought to determine which AR systems are important for survival in acidic foods and which are required for survival in the bovine intestinal tract. Wild-type and mutant E. coli O157:H7 strains deficient in AR system 1, 2, or 3 were challenged with apple cider and inoculated into calves. Wild-type cells, adapted at pH 5.5 in the absence of glucose (AR system 1 induced), survived well in apple cider. Conversely, the mutant deficient in AR system 1, shown previously to survive poorly in calves, was susceptible to apple cider (pH 3.5), and this sensitivity was shown to be caused by low pH. Interestingly, the AR system 2-deficient mutant survived in apple cider at high levels, but its shedding from calves was significantly decreased compared to that of wild-type cells. AR system 3-deficient cells survived well in both apple cider and calves. Taken together, these results indicate that E. coli O157:H7 utilizes different acid resistance systems based on the type of acidic environment encountered.

Severe ADAMTS13 deficiency in adult idiopathic thrombotic microangiopathies defines a subset of patients characterized by various autoimmune manifestations, lower platelet count, and mild renal involvement

The significance of ADAMTS13 deficiency in adult thrombotic microangiopathy (TMA) remains controversial. In an attempt to define the characteristics of adult TMA with severe ADAMTS13 deficiency, we determined 2 groups of patients on the basis of ADAMTS13 activity (undetectable or detectable). Clinical presentation, laboratory values, autoimmune manifestations, and outcome were compared between the groups. Patients were included retrospectively from 12 centers. All fulfilled the diagnosis criteria of TMA. Patients with a history of transplantation, cancer and chemotherapy, and Centers for Disease Control and Prevention (CDC) stage C human immunodeficiency virus (HIV) infection were not included. Forty-six patients were included. Thirty-one patients had an undetectable ADAMTS13 activity (<5%), and the remaining 15 patients had ADAMTS13 activity of >25%. Severe ADAMTS13 deficiency was associated with a plasmatic inhibitor in 17 cases (55%), suggesting an immune-mediated mechanism. Patients with undetectable ADAMTS13 were more frequently of Afro-Caribbean origin than patients with detectable ADAMTS13 activity (48.4% vs 13.3%, respectively; p = 0.03). As opposed to patients with detectable ADAMTS13 activity, patients with severe ADAMTS13 deficiency displayed various autoimmune manifestations that consisted of nondestructive polyarthritis (4 cases) associated in 1 case with malar rash and extramembranous glomerulonephritis, discoid lupus (3 cases), and autoimmune endocrinopathies, Raynaud phenomenon, and sarcoidosis-like disease (1 case each). In patients with severe ADAMTS13 deficiency, antinuclear antibodies, anti-double-stranded DNA antibodies, and anticardiolipin antibodies were positive in 22 (71%) cases, 3 (9.7%) cases, and 1 (3.2%) case, respectively. One patient fulfilled the criteria for the diagnosis of systemic lupus erythematosus. During follow-up, 1 patient with severe ADAMTS13 deficiency developed antinuclear antibodies, and 3 others developed anti-double-stranded DNA antibodies, in association with neurologic manifestations and anticardiolipin antibodies in 1 case. Patients with severe ADAMTS13 deficiency also had a lower platelet count (12 x 10(9)/L; range, 2-69 x 10(9)/L) and less severe renal failure (estimated glomerular filtration rate: 78 mL/min; range, 9-157 mL/min) than patients with detectable ADAMTS13 activity (49.5 x 10(9)/L; range, 6-103 x 10(9)/L; p = 0.0004, and 15.8 mL/min; range, 5.6-80 mL/min; p < 0.0001, respectively). End-stage renal failure occurred in 1 patient with severe ADAMTS13 deficiency and in 3 patients with detectable ADAMTS13 activity (3.2% vs 21.4%, respectively; p = 0.08). Flare-up and relapse episodes and survival were comparable between the groups. Taken together, these data indicate that adult idiopathic thrombotic thrombocytopenic purpura, as defined by severe ADAMTS13 deficiency, may occur preferentially in a particular ethnic group, and is characterized by severe thrombocytopenia, mild renal involvement, and a wide spectrum of autoimmune manifestations that may be completed during follow-up. Indeed, apparently idiopathic thrombotic thrombocytopenic purpura may be considered a specific autoimmune disease.

Methylene blue-photoinactivated plasma vs. fresh-frozen plasma as replacement fluid for plasma exchange in thrombotic thrombocytopenic purpura

BACKGROUND AND OBJECTIVES

Plasma exchange with fresh-frozen plasma (FFP) is the treatment of choice in thrombotic thrombocytopenic purpura (TTP). Methylene blue-photoinactivated plasma (MBPIP) has been proposed as a safer alternative to FFP, but its effectiveness in the treatment of TTP is not well established. The purpose of this study was to investigate whether MBPIP is as effective as FFP in the treatment of TTP by plasma exchange.

MATERIALS AND METHODS

A retrospective analysis was carried out of 56 TTP episodes, occurring between 1990 and 2003, which had been treated by plasma exchange. MBPIP was used for fluid replacement in 27 episodes and FFP in 29. The effect of plasma (MBPIP or FFP) on treatment outcomes was analysed by multivariate logistic regression.

RESULTS

Compared to patients treated with FFP, those receiving MBPIP had an increased risk of dying from progressive TTP [adjusted odds ratio (OR) = 31; 95% confidence interval (CI): 1.2 to > 100], a greater number of recurrences while on plasma exchange therapy (OR = 4.6; 95% CI: 1.2-17), and a lower probability of attaining a sustained remission within 9 days of starting plasma exchange (OR = 5.2; 95% CI: 1.3-20).

CONCLUSIONS

MBPIP seems to be less effective than FFP in the treatment of TTP. It is therefore prudent to avoid MBPIP until therapeutic equivalency to FFP has been established by randomized, controlled trials.

Outcome of plasma exchange therapy in thrombotic microangiopathy after renal transplantation

Thrombotic microangiopathy (TMA) in renal transplant recipients is commonly associated with calcineurin inhibitors (CNIs), though several factors such as vascular rejection, viral infections and other drugs may play a contributory role. We report a series of 29 patients with TMA, all of whom were on CNIs. Though plasma exchange (PEx) is widely used to treat TMA, therapeutic guidelines are not well defined. All our patients were treated with PEx and discontinuation of CNIs. Thrombotic microangiopathy was diagnosed at a median of 7 days post-transplant. The mean decrease in Hgb and platelets during TMA was 66% and 64%, respectively, and peak serum creatinine during TMA was 7.4 +/- 2.9 mg%. Mean duration of PEx therapy was 8.5 (range 5-23) days. Recovery of platelet count to 150K/mcL and Hgb to 8-10 g/dL were used as endpoints for PEx. Twenty-three/29 (80%) patients recovered graft function after PEx. Twenty/23 (87%) patients who recovered were placed back on CNl. Nineteen/20 (95%) patients tolerated reinstitution of CNl without recurrence of TMA. In post-transplant TMA, PEx was associated with a graft salvage rate of 80%, reversal of hematological changes can be used as the endpoint for PEx therapy and CNl can be reintroduced without risk of recurrence in the majority of patients.

Plasma from patients with thrombotic thrombocytopenic purpura induces activation of human monocytes and polymorphonuclear neutrophils

Thrombotic thrombocytopenic purpura (TTP) is a rare but severe disorder characterized by microangiopathic haemolytic anaemia, consumptive thrombocytopenia, neurological involvement and formation of platelet thrombi in the small vessels. The aetiopathology of TTP and the mechanism behind the beneficial effect of plasma exchange with plasma infusion have not yet been fully elucidated. We have studied the effect of plasma from four patients with TTP on human blood phagocyte activation, as measured by reactive oxygen species (ROS) production and CD11b expression. TTP plasma obtained in the acute phase of the disease induced ROS production by human monocytes and enhanced CD11b expression on neutrophils. This activation effect remained in the cryosupernatant but not in the cryoprecipitate made from TTP plasma, and disappeared when a complete response was achieved by plasma exchange. These findings suggest that activated blood phagocytes may be involved in the pathophysiology of TTP.

Relapse of thrombotic thrombocytopenic purpura associated with decreased VWF cleaving activity

Thrombotic thrombocytopenic purpura (TTP) is an uncommon syndrome characterized by reversible, systemic aggregation of platelets in the microcirculation and disseminated microvascular thrombosis. Surgery may precipitate TTP and has been associated with relapse in some patients. However, relapse of this life-threatening disorder is unpredictable. We report a patient with an antecedent history of TTP who experienced a relapse after elective cardiac surgery. In this case, decreased von Willebrand factor (vWF)-cleaving metalloproteinase activity and an inhibitor of this endogenous enzyme were demonstrated preoperatively. These findings suggest that decreased vWF-cleaving metalloproteinase activity and/or the presence of its inhibitor may predict an increased risk for surgical-associated relapse of TTP.

Thrombotic thrombocytopenic purpura: the systemic clumping "plague"

In thrombotic thrombocytopenic purpura (TTP), a multimeric form of von Willebrand factor (vWf) that is larger than ordinarily found in the plasma causes systemic platelet aggregation under the high-shear conditions of the microcirculation. A divalent cation-activated, vWf-cleaving metalloprotease that metabolizes large vWf multimers to smaller forms in normal plasma is severely reduced or absent in most patients with TTP. The vWf-cleaving metalloprotease either is not produced or is defective in children with chronic relapsing TTP. When the enzyme is provided by the infusion of normal plasma, these patients remain free of TTP symptoms for about three weeks. An IgG autoantibody to the vWf-cleaving metalloprotease is found transiently in many adult patients with acute idiopathic, recurrent, and ticlopidine/clopidogrel-associated TTP. These patients require plasma exchange, i.e., concurrent replacement of the inhibited vWf-cleaving metalloprotease by plasma infusion and plasmapheresis. The vWf-cleaving metalloprotease is present in fresh-frozen plasma, in cryoprecipitate-depleted plasma (cryosupernatant), and in plasma that has been treated with solvent and detergent. The pathophysiology of platelet aggregation in bone marrow transplantation/chemotherapy-associated thrombotic microangiopathy, and in the hemolytic-uremic syndrome, is not established. In neither condition is there a severe decrease in plasma vWf-cleaving metalloprotease activity.

von Willebrand factor-cleaving protease inhibitor in a patient with human immunodeficiency syndrome-associated thrombotic thrombocytopenic purpura

Antibodies that inhibit von Willebrand Factor (VWF)-cleaving protease activity occur in patients with acute thrombotic thrombocytopenic purpura (TTP) and often persist in the chronic phase. A deficiency of this protease is likely to be responsible for the generation of ultrahigh VWF multimers and influence the formation of intra-arterial platelet aggregates that result in microangiopathic haemolytic anaemia, thrombocytopenia and end in organ failure. This report demonstrates complete deficiency of VWF-cleaving protease and the presence of a concentration-dependent IgG1 inhibitor in the plasma of a patient with acquired immunodeficiency syndrome (AIDS). These data may contribute to understanding the pathophysiology of human immunodeficiency syndrome (HIV)-related TTP.

Effectiveness of platelet transfusions after plasma exchange in adult thrombotic thrombocytopenic purpura: a report of two cases

Plasma infusion (PI) and plasma exchange (PE) are the most efficient treatment of thrombotic thrombocytopenic purpura (TTP), allowing achievement of complete remission in 60 to 90% of cases. Life-threatening bleeding, related to severe thrombocytopenia, is one of the main complications of the disease. Thrombocytopenia may also preclude invasive procedures such as splenectomy, which may be required during the management of TTP. Platelet concentrates transfusions are usually thought to worsen the disease, especially if not associated with the appropriate treatment of this latter, and thus should be avoided. We report hereon 2 patients with TTP who experienced a surgical procedure i.e., a cholecystectomy for a cholecystitis, and a splenectomy for a refractory TTP. In both patients, the surgical procedure was preceded by a 60 mL/kg plasma exchange with solvent/detergent treated plasma as replacement fluid, followed by platelet transfusion, with a corrected count increment of 57.1% (Patient 1) and 69.3% (Patient 2). Using this sequential treatment, the patients did not experience any deterioration of their status. Both patients had a favorable outcome after surgery. However, until such a procedure will be validated on a larger series of patients, it should be restricted to patients presenting with a refractory life-threatening thrombocytopenia and/or requiring surgery or any kind of invasive procedure. Am. J. Hematol. 68:198-201, 2001. Published 2001 Wiley-Liss, Inc.

Congenital microangiopathic hemolytic anemia and thrombocytopenia with unusually large von Willebrand factor multimers and von Willebrand factor-cleaving protease

Infantile or congenital cases of thrombotic microangiopathy have been reported that were familial and characterized by ongoing microangiopathic hemolysis and thrombocytopenia in the absence of regular fresh-frozen plasma transfusions. The authors describe a child with congenital microangiopathic hemolytic anemia and thrombocytopenia (CMHAT) who has received regular fresh-frozen plasma transfusions since infancy and has never had thrombotic complications. von Willebrand factor (vWF)-cleaving protease activity was studied in the patient's pretransfusion and posttransfusion plasma samples as well as in her parents' plasma. The effects of the patient's and a control subject's plasma on human microvascular endothelial cells were also investigated. Unusually large vWF multimers were present in the patient's plasma both before transfusion (thrombocytopenic) and after transfusion. Unlike cases of chronic relapsing thrombotic thrombocytopenic purpura, vWF-cleaving protease activity was present and treatment of cultured human endothelial cells with the patient's plasma did not induce apoptosis. These findings suggest that the patient with CMHAT may represent a different group in the broad spectrum of thrombotic microangiopathies.

Microangiopathic haemolytic anaemia in metastatic malignancy

In May 1998, a middle-aged woman with a history of breast cancer, diagnosed and treated with a right-sided mastectomy 9 years previously, presented to the Duke University Medical Center with intermittent headaches, slurred speech, left arm numbness and a right facial droop.

Increased plasma thrombomodulin as a vascular endothelial cell marker in patients with thrombotic thrombocytopenic purpura and hemolytic uremic syndrome

Several hemostatic and vascular endothelial cell markers were measured in 39 patients with thrombotic thrombocytopenic purpura (TTP)/hemolytic uremic syndrome (HUS) and in 20 healthy volunteers to examine the relationship between the occurrence of hemostatic abnormality or vascular endothelial cell injury and patient outcome. The plasma levels of von Willebrand factor, tissue plasminogen activator (TPA), plasminogen activator inhibitor (PAI-1), and the TPA-PAI-1 complex were significantly increased in TTP/HUS patients; however, the levels of these markers were not significantly different between TTP/HUS patients who survived and those who died, suggesting that these markers might not be directly related to outcome. The plasma levels of soluble granule membrane protein (GMP)-140 were significantly higher in TTP/HUS patients than in healthy volunteers, suggesting that platelets and vascular endothelial cells are activated or injured in TTP/HUS. There was no significant difference in GMP-140 levels between TTP/HUS patients with good and poor prognoses; this may be owing to the release of GMP-140 from platelets. The plasma thrombomodulin (TM) levels in TTP/HUS patients were significantly higher than in healthy volunteers; the plasma TM levels were significantly higher in patients who died than in patients who survived. These findings showed that TM levels reflect the outcome and that the outcome of TTP/HUS depends on the presence vascular endothelial cell injury. The plasma protein C and antithrombin levels were markedly reduced in TTP/HUS patients who died compared with those who survived. These findings suggest that reduced plasma antithrombin and protein C may be useful markers of systemic vascular endothelial injury. In conclusion, the results of this study showed that the outcome of TTP/HUS is related to vascular endothelial cell injury and that plasma TM, antithrombin, and protein C levels may be useful markers of systemic vascular endothelial cell injury.

Thrombotic thrombocytopenic purpura in acute pancreatitis

Thrombotic thrombocytopenic purpura (TTP) is a rare syndrome of unknown cause with an estimated incidence of one case per million. The disease is characterized by a pentad of symptoms: thrombocytopenia, microangiopathic hemolytic anemia, neurologic changes, renal dysfunction, and fever. It causes thrombosis in the microvasculature of several organs, producing diverse manifestations. Acute pancreatitis (AP) is a well-described consequence of TTP. We report a patient who developed TTP after presenting with AP, suggesting pancreatitis to be the cause, rather than a consequence, of TTP.

[Thrombotic thrombocytopenic purpura (Moschkowitz-syndrome) caused by ticlopidine]

BACKGROUND

Only in a few case reports the thrombotic thrombocytopenic purpura was related to ticlopidine with a controversial discussion about this association.

CASE REPORT

In a 57-year-old female patient, who was admitted with fluctuating central neurological abnormalities and generalized purpura, was made the diagnosis of a thrombotic thrombocytopenic purpura (TTP, Moschcowitz' syndrome). On admission there were a distinct anemia and thrombocytopenia. Corresponding to the hemolysis the laboratory findings showed raised reticulocytes and elevated LDH with > 900 U/l. The peripheral blood smear showed an enrichment of fragmented red cells (15%) and the bone marrow indicated a hyperplastic erythrocytopoesis and a left shift in megakaryocytopoesis. An increase of eosinophilic granulocytes and the tissue basophilic cells directed to a possible allergic phenomenon of the underlying disease. Until 3 weeks before admission she had been on ticlopidine after a left heart catheter with stenting the left coronary artery 6 weeks earlier. Beside taking of acetylsalicylacid and thyroid hormone there was no other regular medication. An early treatment with fresh frozen plasma and plasmapheresis with plasma exchange with fresh frozen plasma led directly to an elevation of thrombocytes and a normalization of hemolytic parameters.

CONCLUSION

This case demonstrates the possible relationship between thrombotic thrombocytopenic purpura and the administration of ticlopidine.

Outcome of thrombotic thrombocytopenic purpura and hemolytic uremic syndrome in Japan

We examined 159 patients with thrombotic thrombocytopenic purpura and hemolytic uremic syndrome in Japan. The subjects were divided in three groups; 90 patients with thrombotic thrombocytopenic purpura, 51 patients with verotoxin-induced hemolytic uremic syndrome, and 18 patients with drug-induced hemolytic uremic syndrome. Eighty-two percent of the patients with thrombotic thrombocytopenic purpura had associated neurological disorders and 78% of drug-induced hemolytic uremic syndrome associated with pulmonary edema. Renal insufficiency was noted in the 69% cases with both hemolytic uremic syndrome groups. Seventeen patients with thrombotic thrombocytopenic purpura had systemic lupus erythematosus and 6 were pregnant. Autoantibody were positive in 53% of thrombotic thrombocytopenic purpura. Seventy-seven percent of patients with thrombotic thrombocytopenic purpura received plasma exchange at 4,000 mL/day three times a week, 71% antithrombotic agents, and 78% steroid administration, respectively. However, 27% of the patients with hemolytic uremic syndrome were treated by hemodialysis in addition to antithrombotic agents. When drug-induced hemolytic uremic syndrome was diagnosed, the drug was immediately discontinued and the patients were treated with antiplatelet agents. Seventy-four percent of the patients with thrombotic thrombocytopenic purpura were alive at 26 weeks compared with 95% of those with hemolytic uremic syndrome. As thrombotic thrombocytopenic purpura had a high mortality rate in Japan, we should carry out early diagnosis and early treatment.

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.

Thrombotic thrombocytopenic purpura: understanding a disease no longer rare

Serial studies of plasma samples from patients during episodes of thrombotic thrombocytopenic purpura (TTP) have often shown either the presence of unusually large (UL) von Willebrand factor (vWf) multimers or, alternatively, absence of the largest plasma vWf forms. The presence of ULvWf multimers in TTP patient plasma may reflect impaired processing of the ULvWf forms released from endothelial cells. The disappearance of ULvWf and large vWf multimers in some TTP patient plasma samples during acute TTP episodes may be predominantly because these ULvWf forms, along with the largest vWf multimers, bind to platelets and cause aggregation. Serial flow cytometry studies of EDTA-whole blood samples from patients with initial episode, intermittent, and chronic relapsing types of TTP confirm that vWf is the likely aggregating agent, perhaps in association with fluid shear stress. The amount of vWf bound to single platelets has been found to be significantly increased during TTP relapses relative to remission periods in patients with all types of TTP. A substance in normal platelet-poor plasma and the cryoprecipitate-depleted fraction of normal plasma (cryosupernatant) is capable in vitro of reversibly reducing the size of ULvWf multimeric forms released by endothelial cells into the somewhat smaller vWf multimers ordinarily in circulation. This activity has characteristics of a limited disulfide bond reductase. The process of ULvWf breakdown may be made irreversible by the tandem proteolysis, catalyzed by a vWf metalloproteinase, of partially reduced vWf multimers. Several patients with chronic relapsing TTP have decreased or absent plasma vWf metalloproteinase activity, apparently on a congenital basis. Adult initial episode and intermittent TTP patients have been found to have vWf metalloproteinase activity inhibited by an autoantibody during, but not after, TTP epidsodes.

Poor outcome in disseminated intravascular coagulation or thrombotic thrombocytopenic purpura patients with severe vascular endothelial cell injuries

Various hemostatic and vascular endothelial cell markers were measured in patients with disseminated intravascular coagulation (DIC), non-DIC, or thrombotic thrombocytopenic purpura (TTP) and in healthy volunteers to examine the relationships between the hemostatic abnormalities or vascular endothelial cell injuries and the patients' outcomes. Although the plasma levels of soluble fibrin monomer, thrombin-antithrombin complex, plasmin-plasmin inhibitor complex, and D-dimer were significantly increased in the DIC patients, there were no significant differences in these markers between the DIC patients who survived and those who died, suggesting that these markers might not be directly related to the patient outcome. The plasma thrombomodulin (TM) levels in the DIC and TTP patients were significantly higher than those in the healthy volunteers, and the plasma TM levels in the patients who died were significantly higher than those in the patients who survived. These findings showed that the TM level reflected the outcome, and that the outcome of the diseases underlying DIC and TTP might depend on vascular endothelial cell injuries. The plasma protein C and antithrombin activities were markedly reduced in the DIC, non-DIC, and TTP patients who died compared to those who survived. These findings suggest that reduced plasma antithrombin and protein C activities are useful markers of systemic vascular endothelial injuries. Although the plasma tissue factor (TF) levels were significantly increased in the DIC patients, there was no significant difference in the plasma TF levels between the DIC patients who died and those who survived. In conclusion, we found that the outcome of the diseases underlying DIC and TTP is related to vascular endothelial cells, and that plasma TM, antithrombin, and protein C are useful markers for systemic vascular endothelial cell injury.

Acquired Deficiency of von Willebrand Factor-Cleaving Protease in a Patient With Thrombotic Thrombocytopenic Purpura

Plasma of patients with thrombotic thrombocytopenic purpura (TTP) has been shown to contain unusually large von Willebrand factor (vWF) multimers that may cause platelet agglutination in vivo. Fresh frozen plasma infusions and plasma exchange represent the most efficient therapy of acute TTP. A specific protease responsible for cleavage of vWF multimers has been recently isolated from normal human plasma and was found to be deficient in four patients with chronic relapsing TTP. We examined the activity of the vWF-cleaving protease in plasma samples collected over a period of 400 days from a further patient with recurrent episodes of TTP who was treated by plasma exchange, plasma infusion, vincristine, corticosteroid therapy, and splenectomy. Complete deficiency of the vWF-cleaving protease was established during the first episode of TTP. The ensuing normalization of the platelet count was associated with the appearance of the protease activity. Three months after remission from the initial TTP event, the vWF-cleaving protease again disappeared and the platelet count gradually decreased. Relapses of severe thrombocytopenia occurred 7 and 11 months after the first acute episode of TTP. Deficient protease activity was associated with the presence in the patient plasma of an inhibitor that was found to be an IgG. Plasma exchange/infusion was followed by a temporary increase in the antibody titer, whereas treatment with vincristine led to a recovery of the platelet count without affecting the inhibitor concentration. Splenectomy and corticosteroid treatment resulted in disappearance of the autoantibody and normalization of the protease activity and of the platelet count. Our data suggest that the thrombocytopenia in this patient with TTP was associated with a lack of the vWF-cleaving protease activity depleted by an autoimmune mechanism. This case, together with our previously reported patients, leads us to conclude that acquired as well as constitutional deficiency of the vWF-cleaving protease may predispose to TTP.

Etiology and treatment of acquired coagulopathies in the critically ill adult and child

Excessive bleeding frequently complicates the care of critically ill patients. Except in the case of trauma or inpatients with known coagulopathies, the bleeding is generally not directly related to the illness that results in admission to the intensive care unit. In general, the causes of the bleeding can be divided into three categories: consumptive coagulopathies, bleeding related to "hepatic issues," and iatrogenic causes. In most circumstances, the pathogenesis and management of these acquired coagulopathies do not differ between the adult and child patient. However, some differences do exist in regards to the clinical manifestations and management of some consumptive coagulopathies. This article reviews the more common causes of bleeding in the critically ill patient and outlines diagnostic and treatment approaches for these patients. Particular emphasis will be placed on the differences in presentation and management where differences exist.

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.

Thrombotic thrombocytopenic purpura: a treatable cause of childhood encephalopathy

We describe two patients less than 13 years of age with thrombotic thrombocytopenic purpura, a rare disorder in childhood. Both children were treated with plasma exchange therapy, which resulted in a rapid resolution of symptoms. This disorder is a cause of childhood encephalopathy, which can be treated effectively with plasma exchange.

Plasma von Willebrand Factor Antigen (vWF:AG) and thrombomodulin (TM) levels in Adult Thrombotic Thrombocytopenic Purpura/Hemolytic Uremic Syndromes (TTP/HUS) and bone marrow transplant-associated thrombotic microangiopathy (BMT-TM)

Endothelial damage is thought to be a contributing factor in the pathogenesis of Thrombotic Thrombocytopenic Purpura/Hemolytic Uremic Syndromes (TTP/HUS). The present studies measured two markers of endothelial cell stimulation and/or activation [von Willebrand Factor (vWF:Ag) and thrombomodulin (TM)] in patients with TTP/HUS disorders and compared them to controls. The patient groups consisted of adults with TTP/HUS, with (n = 13) and without (n = 14) peak Cr levels >2.0 mg/dl. Additionally, 52 patients with Bone Marrow Transplant-associated Thrombotic Microangiopathy (BMT-TM) following allogeneic BMT were evaluated. Both vWF:Ag and TM were elevated in all patient groups compared to controls. TTP/HUS patients with peak Cr >2.0 mg/dl had higher TM levels (P < 0.001) than did those with peak Cr levels below 2 mg/dl. However, thrombomodulin/ creatinine (TM/Cr) ratios did not differ in these two groups nor did they differ from controls. BMT-TM pts had higher vWF:Ag levels and higher TM/Cr ratios than controls and TTP/ HUS, P < 0.001. The median TM/Cr ratio in BMT-TM was 91 (range = 34-229) compared to 38 (range = 29-50) in controls, P < 0.001 and 38 (range = 6 to 156) in TTP/HUS, P < 0.001. Additionally both TM (P < 0.001) and TM/Cr (P < 0.02) were higher in patients with Grades 3 and 4 BMT-TM compared to those with Grade 2 BMT-TM. These results suggest that endothelial cell activation occurs in TTP/HUS and BMT-TM. Since TM/Cr ratios were higher in BMT-TM compared to TTP/HUS, these findings suggest that the mechanism of elevated TM in BMT-TM cannot be explained solely by altered renal excretion. Taken together, these findings strongly indicate a role of endothelial cell damage in BMT-TM.

TTP following ITP in an HIV-positive boy

PURPOSE

To report the previously undescribed development of thrombotic thrombocytopenic purpura (TTP) in a human immunodeficiency virus (HIV)-positive child and discuss the differential diagnosis.

PATIENT AND METHODS

Our patient was a 9-year-old boy with vertically acquired HIV infection and a previous history of immune thrombocytopenic purpura (ITP). Initial presentation, difficulty in diagnosis, clinical course, and subsequent outcome are described.

RESULTS

Rapid resolution of TTP following plasmapheresis was seen.

CONCLUSIONS

Recognition of this treatable though potentially fatal complication in severely ill HIV-infected children requires a high degree of suspicion in view of its diverse clinical manifestations. The long-term outcome may be relatively good.

Thrombotic microangiopathies associated with drugs and bone marrow transplantation

This type of thrombotic microangiopathy more commonly resembles the hemolytic-uremic syndrome (HUS) than thrombotic thrombocytopenic purpura (TTP). The syndrome has been associated with the use of cyclosporin, mitomycin C, combinations of other chemotherapeutic and immunosuppressive agents, and total body irradiation. Endothelial cell injury and von Willebrand factor may be involved in pathogenesis of the intravascular platelet aggregation and tissue (especially renal) ischemia and infarction that characterize the entity. The most effective therapy for thrombotic microangiopathy associated with drugs and bone marrow transplantation has not been determined.

Coagulation disorders in cancer

Coagulation disorders are common in cancer patients. This article reviews the coagulation laboratory findings in these patients and the thromboembolic and hemorrhagic manifestations of malignancy. Among the many topics addressed are Trousseau's syndrome, disseminated intravascular coagulation, and acquired von Willebrand disease. Pathogenesis of the coagulation disorders and recommendations for treatment of various syndromes are discussed.

Hemostatic abnormalities and increased vascular endothelial cell markers in patients with red cell fragmentation syndrome induced by mitomycin C

We examined red cell fragmentation syndrome (RCFS) induced by mitomycin C (MMC) (13 patients), by thrombotic thrombocytopenic purpura (TTP) (17 patients), and by disseminated intravascular coagulation (DIC) (15 patients). Plasma cytokine levels were increased in the TTP and DIC patients, but not in those whose RCFS was induced by MMC, suggesting that the activation of the immune system plays an important role in the pathogenesis of RCFS due to TTP and DIC but did not in RCFS due to MMC. Plasma thrombomodulin, tissue type plasminogen activator, and plasminogen activator inhibitor-I levels were increased in all RCFS patients, suggesting that RCFS, whether MMC induced, or due to TTP or DIC, might be associated with vascular endothelial cell injury. In TTP, von Willebrand factor (vWF) antigen and high molecular weight vWF multimer levels were reduced, possibly as a result of microthrombus consumption. The hemostatic data in this study showed that the TTP patients were in a hypercoagulable state without hyperfibrinolysis, and that DIC patients were in both a hypercoagulable and a hyperfibrinolytic state, whereas hemostatic abnormalities were slight in patients with MMC induced RCFS. These findings suggest that vascular endothelial cell injuries might be associated with RCFS, and that those injuries in MMC-induced RCFS might not be related to microthrombi or an activated immune system.

Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome: a multivariate analysis of factors predicting the response to plasma exchange

The aim of this study was to investigate pretreatment prognostic factors that could be useful in predicting the response to plasma exchange in thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS). Thirty-two patients with TTP/HUS, treated with plasma exchange at our institution from 1980 to 1994, were studied. The main clinical and laboratory data at the beginning of plasma exchanges were analyzed by the Cox stepwise logistic regression, applied to either treatment failure or death. Seventeen (53%) patients attained a complete remission and 22 (69%) survived (five in advanced renal failure and long-term hemodialysis). Longer delay in initiating plasma exchanges, presence of stupor or coma, and higher creatinine levels at the beginning of plasma exchanges were independent predictors of treatment failure. Stupor or coma at the beginning of plasma exchanges was the only predictor of mortality from unremitted TTP/HUS. Hemoglobin levels, platelet count, and LDH activity, traditionally envisaged as markers of disease activity, neither correlated with previous duration of TTP/HUS nor had any prognostic value. Early diagnosis of TTP/HUS and prompt initiation of intensive plasma exchange emerged from this study as the most effective interventions for improving the prognosis of TTP/HUS patients.

Thrombotic thrombocytopenia induced in dogs and pigs. The role of plasma and platelet vWF in animal models of thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenia with severe depletion of plasma von Willebrand factor (vWF) was induced in normal large animals (5 dogs and 2 pigs) by botrocetin, a Bothrops factor requiring vWF for platelet agglutination. Botrocetin (90 to 100 U/kg, 2.14 to 2.38 mg/kg, in a single i.v. injection) reduced plasma vWF activity to < 0.1 U/mL for 24 hours. During this period, multimeric analysis of plasma vWF antigen (Ag) revealed the loss of intermediate- and high-molecular-weight forms with a concomitant increase in lower molecular weight forms. A moderate reduction in factor VIII (FVIII) activity was observed. The vWF reduction was accompanied by transient thrombocytopenia and prolonged bleeding times during the deficiency state. Occlusive platelet thrombi were detected by transmission electron microscopy in the microcirculation of lung and spleen but not kidney or brain 30 minutes after the botrocetin injection. Recovery of plasma vWF and platelet count occurred within 48 hours and was associated with the appearance in the plasma of unusually large forms of vWF:Ag multimers. The vWF:Ag multimer distribution was normal at 72 hours. The ultrastructural distribution of vWF in unstimulated normal porcine and canine platelets was examined by using immunogold staining. VWF was detected in the alpha-granules of normal pig platelets but was not observed in platelets from normal dogs. However, both animals developed thrombotic thrombocytopenia when injected with botrocetin. A second group of animals (2 dogs and 3 pigs) with von Willebrand disease (vWD) was given a single botrocetin injection (90 to 100 U/kg). No thrombocytopenia occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Thrombotic thrombocytopenic purpura as the cause of death in an HIV-positive child

A case of fatal thrombotic thrombocytopenic purpura (TTP) in a pediatric patients with HIV infection is reported. The diagnosis was made at autopsy based on the presence of platelet microthrombi in multiple organs, including the cardiac conduction system. The disease presented atypically with hemorrhagic manifestations, thrombocytopenia, and hemolytic anemia, without significant accompanying neurologic and renal abnormalities. Autoimmune-based thrombocytopenia has been well documented in the presence of HIV infection in both the adult and the pediatric population. We believe this to be the first reported case of TTP in an HIV-positive child.

Endothelial cell function and thrombosis

Healthy endothelium is a metabolically active interface between the blood and extravascular tissues. Its intimal surface is anticoagulant and antithrombotic, and it secretes a variety of molecules involved in regulating platelet function and blood coagulation. The rapid interactions between platelets, their secreted components, or thrombin and endothelial cells at sites of vessel damage ensure the local secretion of mediators such as prostacyclin and nitric oxide that limit the intravascular growth of the haemostatic plug. There is considerable evidence that a decreased ability of endothelial cells to synthesize NO contributes to the pathogenesis of arterial disease. Local deficiency of PGI2 synthesis has also been implicated in the thrombotic problems in haemolytic uraemic syndrome. Endothelium is also the source of circulating von Willebrand factor, important for efficient platelet adhesion. Chronically elevated plasma levels of vWF in a series of diseases where there is vascular pathology apparently reflect endothelial cell damage or activation, and may contribute to the prothrombotic tendency they exhibit. They may be compounded by decreased levels of the surface anticoagulant thrombomodulin, if the increased concentrations of the soluble forms of thrombomodulin detected in the circulation under similar conditions are a reflection of loss from the endothelium. Further alterations of function in a procoagulant/prothrombotic direction take place when endothelial cells are exposed to certain cytokines or lipopolysaccharide. Tissue factor synthesis is induced, thrombomodulin expression is decreased, and there is enhanced sensitivity of vWF secretion. In addition, the balance of tissue-type plasminogen activator and plasminogen activator inhibitor type I secretion is changed in favour of the latter. These processes are each likely to contribute to the occurrence of disseminated intravascular coagulation which can accompany septic shock.