Novel platelet-agglutinating protein from a thrombotic thrombocytopenic purpura plasma.

A novel platelet-agglutinating protein (PAP) was purified approximately 2,000-fold from the plasma of a patient with thrombotic thrombocytopenic purpura (TTP) by ammonium sulfate fractionation, DEAE-Sephacel and concanavalin A-Sepharose chromatographies. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, with and without reduction, this preparation revealed a major protein band with a molecular weight of 37,000, and a minor band with a molecular weight of 32,000-34,000. After elution from the gel, only the 37,000-mol wt protein corresponding to the major band induced the platelet agglutination. When four normal plasmas and the recovery plasma from the same TTP patient were subjected to the similar purification steps, the 37,000-mol wt major band was absent. The 125I-PAP bound to the platelets in a concentration-dependent manner. The platelet agglutination induced by PAP was not inhibited by hirudin, heparin in the presence of antithrombin III, phenylmethylsulfonyl fluoride, apyrase, aspirin, or prostaglandin I2. However, it was inhibited by IgG from normal adults and from the same TTP patient after recovery. The anti-37,000-mol wt PAP antiserum prepared in the rabbit formed a single precipitin line against the highly purified PAP. Using this antiserum in the Western immunoblotting, the 37,000-mol wt protein band was found in the three TTP plasmas, of which the platelet-agglutinating activity was inhibited by the anti-37,000-mol wt PAP IgG. The 37,000-mol wt immunoprecipitin band was absent in the plasmas obtained from another two TTP patients, two normal subjects, two patients with idiopathic thrombocytopenic purpura, and two patients with disseminated intravascular coagulation. These results suggest that the 37,000-mol wt PAP is present only in certain cases of TTP, and is likely to be responsible for the formation of platelet thrombi in the microcirculation.     

A case of thrombotic thrombocytopenic purpura refractory to plasma exchange.

We experienced a case of thrombotic thrombocytopenic purpura (TTP) finally relieved after 74 sessions of plasma exchange (PE). The patient was a 56-year-old male. In August 1999, he was examined in emergency because of brown urine and a lowered level of consciousness. As TTP was suspected according to the laboratory findings of abnormally high lactate dehydrogenase and total bilirubin, decreased platelet counts, and numerous fragmented erythrocytes, he was admitted to the ICU of our hospital. Immediately after admission, PE was started consecutively. Upon concomitant use of antiplatelet drugs and prostacyclin, the level of platelet counts recovered to 100,000/microl once, but decreased again. Thus, in addition to the PE, prednisolone and vincristine were administrated, which elevated the level of platelet counts to 200,000 to 300,000/microl. Since the erythrocyte fragmentation was noted frequently, PE was continued twice a week. From the 60th day of admission onward, however, his body temperature rose above 40 degrees C with a rapid increase of C-reactive protein. A blood culture detected methicillin-resistant Staphylococcus aureus (MRSA) which derived from a left lung abscess. During the course of anti-MRSA treatment, he presented acute renal failure and acute hepatic dysfunction, but survived because of the combined therapy. He was discharged on the 180th day of admission. These results suggest that a combined therapy of steroid and vincristine is effective to treat TTP refractory to PE, but careful attention should be paid to the complications caused by immunosuppression.     

Idiopathic thrombocytopenic purpura during remission of thrombotic thrombocytopenic purpura

Three patients were treated empirically with anti-platelet agents, prednisone, plasmapheresis, and prostacyclin for the classical clinical syndrome of thrombotic thrombocytopenic purpura (TTP). All three patients initially responded, then relapsed after one to 13 months with a clinical picture characteristic of immunogenic thrombocytopenic purpura (ITP). At relapse, all three had thrombocytopenia without microangiopathy or other causes of thrombocytopenia. All responded to splenectomy. This complication of TTP may become more common with improved survival in TTP. Recognition may prevent inappropriate therapy.     

Chronic relapsing thrombotic thrombocytopenic purpura in adult onset Still's disease

We report the first known case of chronic relapsing thrombotic thrombocytopenic purpura associated with adult-onset Still's disease. The patient presented with diffuse arthralgias, sore throat, and a maculopapular rash involving the trunk and extremities; she was hospitalized with fever and confusion. Thrombocytopenia, renal failure, and microangiopathic hemolytic anemia developed within several days. After a diagnosis of thrombotic thrombocytopenic purpura was made, she responded well to a series of plasma exchanges. Evaluation for infection, autoimmune disorders, and malignancy was negative. She was discharged to home in good condition, with normal renal function and normal platelet count. Two more episodes of TTP developed 7 and 9 months after the first hospitalization. The diagnosis of adult-onset Still's disease was then determined on the basis of clinical and laboratory criteria. She was successfully treated with plasma exchange, prednisone, and azathioprine. She later had splenectomy and has subsequently been without recurrence of thrombotic thrombocytopenic purpura for 2 years.     

血浆置换治疗血栓性血小板减少性紫癜临床疗效的观察

目的观察血浆置换治疗血栓性血小板减少性紫癜的临床疗效。方法回顾分析2013年1月—2018年6月本院14例确诊为血栓性血小板减少性紫癜患者的临床特征及进行血浆置换治疗后的疾病转归情况,分析血浆置换治疗过程中不良反应发生情况。结果 14例血栓性血小板减少性紫癜患者共进行了47次血浆置换,经过血浆置换治疗后10例患者病情好转恢复出院,血浆置换治疗血栓性血小板减少性紫癜患者的总有效率为71.4%。47次血浆置换术中共发生了3次不良反应,其不良反应发生率为6.4%。结论血浆置换是治疗血栓性血小板减少性紫癜的有效方法,患者一旦确诊或高度怀疑为血栓性血小板减少性紫癜时需尽早开始血浆置换治疗。     

Diagnosis of thrombotic thrombocytopenic purpura

As hallmark of TTP, generalized hyaline thrombi in the patient's microcirculation is known. These thrombi are composed of platelets and VWF. A severe defect of the VWF cleaving protease (VWF-CP) was found in all known patients with the inherited form of TTP. In contrary, although a severe deficiency of VWF-CP is specific for the acquired form, too, only a fraction of these patients is characterized by a severe deficiency. In most patients with a severe deficiency autoantibodies directed against VWF-CP is detectable in plasma. However, many patients with acquired TTP do not show any severe deficiency. Because treatment differs in inherited and acquired forms and as persistance of autoantibodies during clinical remission is of prognostic value, the determination of the activity of VWF-CP and of antibodies against VWF-CP are important parts in the workup of patients with TTP. In all methods for the determination of the activity of VWF-CP the first step is proteolysis of a specific substrate for the protease. In the second step the activity of the protease is measured by analysis of the residual VWF multimers, by the generation of specific fragments, by using the residual VWF:CB or VWF:RCo as marker of the loss of multimers or with help of specific monoclonal antibodies. In less than 30 min the cone and plate(let) aggregometer helps to distinguish between different forms of thrombotic microangiopathies. While adhesion and aggregation of platelets from a healthy person are clearly enhanced after addition of a small amount of plasma from a TTP patient, both characteristics are weakened by plasma from patients with other forms of thrombotic microangiopathy (dilution effect). Molecular genetics are established methods in the differentiation between inherited and acquired forms of TTP in those cases without autoantibodies against VWF-CP.     

Treatment of thrombotic thrombocytopenic purpura with plasma infusions and cyclophosphamide

Our patient presented with thrombotic thrombocytopenic purpura. Treatment failed despite splenectomy, corticosteroids, dextran, and antiplatelet drugs. Plasma infusions induced neurologic recovery, but hematologic improvement could not be sustained when they were discontinued. Cyclophosphamide, however, induced a sustained remission.     

Complement activation in thrombotic thrombocytopenic purpura

Summary. Background: Ultra‐large von Willebrand factor and deficiency of its cleaving protease are important factors in the events leading to thrombotic microangiopathy; however, the mechanisms involved are only partly understood. Whereas pathological activation of the alternative complement pathway is linked to atypical hemolytic uremic syndrome, the role of complement activation in thrombotic thrombocytopenic purpura (TTP) is unknown. The aim of this study was to investigate whether signs of complement activation are characteristic of TTP. Patients and methods: Twenty‐three patients with TTP (18 women, median age 38 years) and 17 healthy controls (13 women, median age 38 years) were included. Complement parameters (C3, Factors H, I, B and total alternative pathway activity) together with complement activation fragments (C3a) or complexes (C1rs‐INH, C3bBbP, sC5b9) were measured by ELISA or RID. ADAMTS13 activity and anti‐ADAMTS13 inhibitory antibodies were measured by the VWF‐FRET73 assay. Results: Increased levels of C3a, and SC5b9 were observed in TTP during acute episodes, as compared with healthy controls. Decreased complement C3 levels indicative of complement consumption occurred in 15% of acute TTP patients. Significant decrease of complement activation products C3a and SC5b9 was observed during plasma exchange (PEX). The sustained presence of anti‐ADAMTS13 inhibitory antibodies in complete remission was associated with increased complement activation. Conclusion: These data document in an observational study the presence of complement activation in TTP. Further investigation is needed to determine its potential pathogenetic significance.     

Therapeutic plasma exchange for thrombotic thrombocytopenic purpura with refractory thrombocytopenia

Thrombotic thrombocytopenic purpura (TTP) is an acute, life‐threatening illness with disseminated platelet‐rich thromboses of small vessels that variably presents with the classic clinical “pentad” of microangiopathic hemolytic anemia, thrombocytopenia, fever, altered mental status, and acute kidney injury. Most cases are caused by an acquired autoantibody to ADAMTS13, a metalloproteinase that cleaves large von Willebrand Factor (vWF) multimers. The mainstay of treatment is daily therapeutic plasma exchange (TPE), sometimes with adjunctive pharmacologic immunosuppression. TPE is generally continued until the platelet count is greater than 150 × 10³/µL and the lactate dehydrogenase is near normal for 2‐3 consecutive days. Unfortunately, there is no clear guidance for when thrombocytopenia is refractory for a prolonged period of time. The following case describes such a scenario in which consecutive ADAMTS13 activity and inhibitor levels were used to guide the decision to stop treatment with TPE in a patient who failed to recover their platelet count.     

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

Thrombotic thrombocytopenic purpura (TTP) is a dramatic intravascular platelet-clumping disorder characterized by microangiopathic hemolytic anemia, thrombocytopenia, neurologic abnormalities, renal insufficiency and fever. TTP is a rare disease but is almost always fatal if untreated. More than 80% of patients survive with plasma therapy. In healthy individuals, the proteolytic cleavage of ultralarge von Willebrand factor (vWF) multimers prevents spontaneous clumping of platelets in the microcirculation. Patients with TIP have either severe congenital deficiency of von Willebrand factor-cleaving protease (vWF-cp), or have autoantibodies that inhibit the protease. Determination of vWF-cp levels in patient plasma helps to distinguish between TTP and other thrombotic microangiopathies with similar clinical signs and symptoms. vWF-cp is a member of the ADAMTS family of metalloproteases and has been designated ADAMTS13.     

Seasonal association of thrombotic thrombocytopenic purpura

BACKGROUND: Thrombotic thrombocytopenic purpura (TTP), a thrombotic microangiopathy, is a clinical diagnosis, characterized by microangiopathic hemolytic anemia and thrombocytopenia without another likely explanation. Some initiators of the disease are well represented in the literature, such as certain drugs, malignancies, and viral illness; however, there are less objective factors still being investigated, with references to hormonal, stress, and seasonal variations considered anecdotally. A better insight of these factors would aid in understanding the pathophysiology of the disease. STUDY DESIGN AND METHODS: We performed a retrospective review of all idiopathic TTP cases treated with therapeutic plasma exchange at our institution from 1999 to 2008 to determine whether there was seasonal variation in TTP presentation. Seasons were defined as follows: winter = December to February; spring = March to May; summer = June to August; and fall = September to November. With the use of Poisson regression models, the incidence between seasons was compared. RESULTS: During this study period, a total of 97 cases were recorded. Summer had the highest occurrence of TTP (35%). This was significant compared to the fall (p = 0.012) and the winter (p = 0.019). There were more cases in the summer compared to the spring, but this was not significant. CONCLUSION: In our population, there was a significant difference in the number of TTP cases presenting in summer compared to fall and winter. This supports a possible environmental, infectious, or physiologic influence associated with the summer.     

Reactive hemophagocytic syndrome associated with thrombotic thrombocytopenic purpura during therapeutic plasma exchange.

Hemophagocytic lymphohistiocytosis (HLH) is characterized by fever, cytopenia, splenomegaly, and lymphohistiocytic proliferation with hemophagocytosis. Sporadic, familial, and reactive HLH varieties exist. The latter, also termed the reactive hemophagocytic syndrome (RHS), has been associated with a variety of infectious and noninfectious etiologies. Activation of monocytes in RHS is due to stimulation by high levels of activating cytokines. RHS has not been associated previously with thrombotic thrombocytopenic purpura (TTP). TTP is a multisystem disorder characterized by consumptive thrombocytopenia, microangiopathic hemolytic anemia, neurologic symptoms, renal impairment, and fever. We report on a 33 year old male patient with a classic picture of TTP who initially responded to therapeutic plasma exchange but then became refractory to treatment and developed RHS. It is likely that a specific pathophysiology involving the activation of neutrophils during TPE is present for the development of cytokine-induced hemophagocytosis during TTP treatment. The consequent development of RHS possibly caused early TTP relapse.