TTP and ADAMTS13: When Is Testing Appropriate?

Acute pancreatitis complicated by hemolytic uremic syndrome: a pediatric case

Background

Hemolytic uremic syndrome (HUS) is characterized by microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and acute kidney injury. The acute pancreatitis-associated HUS is a rare entity, and this case is one of the few pediatric cases reported.

Case presentation

A 17-year-old girl referred to the emergency department with complaints of abdominal pain, fever, and vomiting. The skin and sclera were icteric. Murphy’s sign was positive. Hemogram was normal, biochemical analysis revealed an increase in liver function tests and cholestasis enzymes. Abdominal CT revealed multiple stones in the hydropic gallbladder lumen and the pancreas was edematous. With a diagnosis of acute pancreatitis supportive treatment was started. Acute kidney failure, cholestasis, anemia, and thrombocytopenia developed at the 2nd day of follow-up. Thrombotic thrombocytopenic purpura was excluded with normal ADAMTS-13 level. Intermittent hemodialysis and plasma exchange (PE) treatments were initiated, considering pancreatitis-related HUS. On the 3rd day of PE, the patient’s urine output exceeded 1 cc/kg per hour. No schistocyte was found in the peripheral smear after 7 PE and 5 hemodialysis sessions. Anemia, thrombocytopenia, and kidney functions improved. On the 15th day of the follow-up, endoscopic retrograde cholangiopancreatography performed, and gallbladder stones were removed.

Conclusion

The pathogenesis of HUS developing after acute pancreatitis is not fully understood. The mechanism proposed is that acute pancreatitis triggers cytokine release, resulting in endothelial damage and HUS. In conclusion, HUS may rarely develop in patients with acute pancreatitis. With the early diagnosis and appropriate treatment, the kidney functions can be completely normalized.

Thrombotic Microangiopathy Secondary to Pancreatitis: A Diagnostic Enigma

The association between thrombotic microangiopathy (TMA) and pancreatitis is well known. However, TMA leading to pancreatitis is more common than the latter. TMA and renal failure are both poor prognostic markers in acute pancreatitis. TMA, if not managed timely, can lead to severe morbidity and mortality. We report a case of a young boy in whom decisive and timely diagnosis and management of TMA post pancreatitis helped in complete patient and renal recovery.

Thrombotic microangiopathy with renal injury: an approach for the general physician

Thrombotic microangiopathy with renal dysfunction is a haematological and renal emergency warranting urgent diagnosis and intervention. As the potential underlying causes may be complex, assessment and management can be challenging for treating clinicians, and a timely and collaborative approach between general physicians, haematologists and nephrologists may be extremely helpful in order to optimise clinical outcomes. This paper will aim to build an understanding of different potential presentations of thrombotic microangiopathies and provide a practical framework for diagnosis and management, using a case-based discussion format, for acute and general physicians. Some aspects of subsequent specialist management are also discussed.

Acquired Thrombotic Thrombocytopenic Purpura in a Newly Diagnosed HIV Patient: A Case Report and Literature Review

Thrombotic thrombocytopenic purpura (TTP) is a rare but a potentially fatal condition. Although the majority of TTP cases are of unknown etiology, certain viral infections, malignancies, and medications have been linked to the acquired form of the illness. Regardless of the underlying etiology, TTP remains a great challenge diagnostically and therapeutically. TTP remains a very uncommon complication of HIV. We reviewed the current literature to better understand the relationship between HIV and TTP and address some of the major obstacles that may impede or delay the correct diagnosis. Here, we present a case of a 28-year-old male with complaints of light-headedness, fatigue, and gingival bleeding. He was found to have severe anemia and thrombocytopenia. He tested positive for the HIV and was then diagnosed with TTP. Despite needing endotracheal intubation for airway protection, he clinically improved with packed red blood cells, plasmapheresis, and highly active antiretroviral therapy.

Thrombotic Thrombocytopenic Purpura Associated with Myelodysplastic Syndrome

Myelodysplasia and thrombotic thrombocytopenic purpura (TTP) are both rare diseases. TTP is a blood abnormality in which blood clots form in blood vessels leading to fatal outcomes. Myelodysplastic syndrome is a group of disorders caused by poorly formed blood cells or ones that do not work properly. We are hereby presenting the case of a 69-year-old female who presented with anemia, thrombocytopenia, changes in mental status and reduced kidney function, and further investigations revealed that the patient had underlying myelodysplasia.

Thrombotic Thrombocytopenic Purpura Associated with Dermatomyositis

Dermatomyositis and thrombotic thrombocytopenic purpura (TTP) are both rare diseases. TTP is a blood abnormality in which blood clots form in blood vessels leading to fatal outcomes. Dermatomyositis is an inflammatory myopathy which causes a distinctive skin rash and muscle weakness. We are hereby presenting the case of a 27-year-old female who presented with characteristic skin findings on the face pathognomic of dermatomyositis and further investigation revealed that she had underlying TTP.

A STARD-compliant prediction model for diagnosing thrombotic microangiopathies

Aim of the study was the definition of a predictive model for the initial diagnosis of thrombotic microangiopathies (TMA). We retrospectively collected data on all adult patients admitted to the Gemelli Hospital from 2010 to 2014. ICD-9 codes from primary diagnoses were used for TMA diagnosis. Demographic and laboratory characteristics on admission of patients with TMA were then compared with a random sample of 500 patients with other diagnoses. The prediction model was externally validated in a cohort from another hospital. Overall, 23 of 187,183 patients admitted during the study period received a primary diagnosis of TMA. LDH (OR 1.26, 95% CI 1.05, 1.63) and platelets (OR 0.96, 95% CI 0.94, 0.98) were the only independent predictors of TMA. The AUROC of the final model including only LDH and platelets was 0.96 (95% CI 0.91, 1.00). The Hosmer-Lemeshow (HL) test (p = 0.54) suggested good calibration. Our model also confirmed good discriminatory power (AUROC 0.72 95% CI 0.60, 0.84) and calibration (HL test p = 0.52) in the validation sample. We present a simple prediction model for use in diagnosing TMA in hospitalized patients. The model performs well and can help clinicians to identify patients at high risk of TMA.

A rare case of thrombotic microangiopathy triggered by acute pancreatitis

Thrombotic microangiopathy (TMA) occurring after acute pancreatitis is rarely described. Without prompt intervention, TMA can be, and often is, lethal, so prompt recognition is important. Here, we present a case of a 61-year-old woman with a history of alcohol misuse who presented with epigastric pain, nausea and vomiting after binge drinking. Elevated serum lipase and imaging were suggestive of acute-on-chronic pancreatitis. Although the patient's symptoms of acute pancreatitis subsided, her anaemia, thrombocytopenia and acute kidney injury worsened. A peripheral blood smear revealed schistocytes, prompting suspicion for TMA. Therapeutic plasma exchange (TPE) was promptly initiated and she completed 10 TPE sessions that improved her anaemia and serum creatinine and resolved the thrombocytopenia. Since TPE was effective and the ADAMTS13 assay revealed 55% activity in the absence of anti-ADAMTS13 IgG prior to initiation of therapy, a confident diagnosis of TMA caused by acute pancreatitis was made. There was no evidence of relapse 2 years later.

Thrombotic thrombocytopenic pupura (TTP) dinner symposium proceedings

Answering TTP was established to engage the thrombotic thrombocytopenic purpura (TTP) community to further the common goals of patient support, education of patients and medical professionals, and the funding of research to improve the treatment and care of TTP patients. Answering TTP convened a dinner symposium on 23 June 2015 in Toronto, Canada during the International Society of Thrombosis and Haemostasis (ISTH) Congress to bring TTP clinicians and research together to highlight the key clinical and research questions in the field. These questions are increasingly important given the recent advances and novel therapies that have or will soon enter clinical study for patients with TTP.

Von Willebrand factor-cleaving protease activity in thrombotic microangiopathy: first report from iran

BACKGROUND

Thrombotic microangiopathy (TMA) is a rare but devastating small vessels disorder that is characterized by intravascular platelet thrombi, thrombocytopenia, and various degrees of organ ischemia and anemia, which is due to erythrocyte fragmentation in microcirculation.

OBJECTIVES

The Aim of this study was to determine the von Willebrand factor-cleaving protease (ADAMTS13) activity during the acute phase of TMA. We also investigated inhibiting antibodies against ADAMTS13 in these patients.

PATIENTS AND METHODS

In a collaborative work with Mario-Negro institute of pharmacological research in Bergamo-Italy, we registered the clinical and laboratory data, collected the serum samples, and transferred the samples to the laboratories. Serum samples were taken before the start of plasmapheresis or at least 15 days after the final exchange.

RESULTS

We recruited 40 patients (14 males and 26 females) with the mean age of 46.12 ± 17.26 years. The mean activity of ADAMTS13 was 34.58% ± 21.83%. Two patients had inhibitory antibodies against ADAMTS13 with profound deficiency of ADAMTS13 activity (< 6%). Infectious diseases were the most common underlying condition, followed by systemic lupus erythematous.

CONCLUSIONS

Majority of patients had an underlying condition and had various ADAMTS13 activity. The presence of inhibiting antibodies and accompanied complete deficiency of ADAMTS13 activity is an indicator of severity.

Clinical features and prognostic factors of thrombotic thrombocytopenic purpura associated with systemic lupus erythematosus: a literature review of 105 cases from 1999 to 2011

This study aims to review clinical features, treatments, and prognostic factors of thrombotic thrombocytopenic purpura (TTP) associated with systemic lupus erythematosus patients (sTTP). The case reports of sTTP published in world literature from 1999 to 2011 were collected, and 105 cases were divided into death group and survival group. The epidemiologic characteristics, clinical manifestations, laboratory examinations, treatments, and prognostic factors were analyzed. We found that coexistence of renal and neurological impairments were significantly frequent in the death group (100 %) than in the survival group (56.5 %) (P = 0.002). Type IV was predominant in 57.7 % of renal pathological damage, followed by type V (11.5 %), type II (5.8 %), and thrombotic microangiopathy (TMA) (5.8 %). TMA appeared more frequently (50 %) in the death group than in the survival group (6.25 %) (P = 0.042). End-stage renal disease occurred in nine cases with type IV in five (55.6 %), type TMA in one (11.1 %), and unspecified in three cases (33.3 %). Of 32 cases, 40.6 % showed severe ADAMTS13 deficiency and returned to normal or mildly deficient after remission. The total mortality rate of sTTP was 12.4 % and the mortality rate of patients with infection (27.3 %) was significantly higher than those without infection (8.4 %) (P = 0.028). Plasma exchange and glucocorticoids were administrated in over 80 % of cases with 65.7 % remission rate, while additional cytotoxics or rituximab was mostly used in refractory sTTP and achieved over 90 % of remission rate. Above all, coexistence of renal and neurological impairments, infection, and renal damage with type IV or TMA might denote a poor prognosis of sTTP.

Analysis of clinical and laboratory characteristics in 42 patients with thrombotic thrombocytopenic purpura from a single center in China

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disease characterized by microvascular platelet deposition and thrombus formation with resulting microangiopathic hemolytic anemia. Deficiency of the von Willebrand factor cleavage protease, also known as ADAMTS 13, has been implicated as an important etiological factor in TTP. Little studies were obtained on Chinese patients with TTP until now. Our aim was to analyze the clinical features, outcome and laboratory characteristics of Chinese TTP patients, and determine whether plasma ADAMTS 13 activity is decreased in TTP and its diagnostic value for TTP. Forty-two TTP patients (29 females; 13 males) admitted to our hospital from 1998 to 2010 were analyzed. There were 34 patients (81%) with the triad of TTP, including hemolytic anemia, thrombocytopenia and neurologic abnormalities; 7 (16.7%) had the classical pentad of TTP. Major etiologic factors were acquired autoimmunological abnormalities (31%); no familial TTP was identified in this series. The schistocytes of peripheral blood smears were present in all cases with a mean frequency of 4.6% (range from 0.3% to 13.4%). Plasma ADAMTS 13 activity was determined in 22 patients with the FRET-vWF86 assay. Only 4 idiopathic TTP patients (18.2%) had severe ADAMTS 13 deficiency (activity<10%); 9 (40.9%) had moderate decrease of ADAMTS 13 activity (activity: 10-40%); another 9 (40.91%) had normal ADAMTS 13 activity (>40%). T lymphocyte subpopulation was measured in 23 TTP patients with FACS Calibur; 14 of the 23 (60.9%) had significantly decreased CD4 cells count and CD4/CD8 ratio, suggesting cellular immune dysfunction may be involved in the pathogenesis of TTP. In the studies, plasmapheresis is the main therapeutic method. 26 of 31 patients (83.9%) accepting plasmapheresis achieved complete remission; those patients who only underwent plasma infusion had low remission rate (18.2%) and high mortality (9/11; 81.8%). Four patients with packed RBC infusion manifested transient exacerbation of neurologic or psychiatric symptoms. In conclusion, the diagnosis of TTP in China is still based on clinical features including evidence of microangiopathic hemolysis. Severe ADAMTS 13 activity deficiency might be a valuable indicator for idiopathic TTP diagnosis. Further studies are needed to determine the real value of ADAMTS 13 activity for TTP diagnosis and whether T lymphocytes subset dysregulation plays important role in TTP pathogenesis.

Update on hemolytic uremic syndrome: Diagnostic and therapeutic recommendations

Hemolytic uremic syndrome (HUS) is a rare disease. In this work the authors review the recent findings on HUS, considering the different etiologic and pathogenetic classifications. New findings in genetics and, in particular, mutations of genes that encode the complement-regulatory proteins have improved our understanding of atypical HUS. Similarly, the complement proteins are clearly involved in all types of thrombotic microangiopathy: typical HUS, atypical HUS and thrombotic thrombocytopenic purpura (TTP). Furthermore, several secondary HUS appear to be related to abnormalities in complement genes in predisposed patients. The authors highlight the therapeutic aspects of this rare disease, examining both "traditional therapy" (including plasma therapy, kidney and kidney-liver transplantation) and "new therapies". The latter include anti-Shiga-toxin antibodies and anti-C5 monoclonal antibody "eculizumab". Eculizumab has been recently launched for the treatment of the atypical HUS, but it appears to be effective in the treatment of typical HUS and in TTP. Future therapies are in phases I and II. They include anti-C5 antibodies, which are more purified, less immunogenic and absorbed orally and, anti-C3 antibodies, which are more powerful, but potentially less safe. Additionally, infusions of recombinant complement-regulatory proteins are a potential future therapy.

Acquired thrombotic thrombocytopenic purpura in children: a single institution experience

OBJECTIVE

To describe the clinical features, treatment and prognosis of acquired thrombotic thrombocytopenic purpura (TTP) in children based on a single institution experience.

METHODS

This study is a retrospective review of all 12 children with TTP seen at New York Medical College- Westchester Medical Center during a period of 15 y from 1993 to 2008.

RESULTS

There were 7 females and 5 males with acquired TTP, with a median age of 13 (range, 6-17); and no cases of congenital TTP. The classic pentad of TTP (microangiopathic hemolytic anemia, thrombocytopenia, neurologic symptoms, renal dysfunction and fever) was seen in only three patients. Nine had renal involvement; eight had neurologic symptoms; and four had fever. All 12 patients had thrombocytopenia, anemia, and elevated LDH. Nine had idiopathic TTP. Three patients had one of the following underlying disorders: systemic lupus erythematosus, mixed connective tissue disorder, and aplastic anemia (post-bone marrow transplant on cyclosporine). ADAMTS13 level was decreased in 7 of 8 patients studied. Eight of 10 patients achieved remission with plasmapheresis alone. Two needed additional treatment before achieving remission. Two had one or more relapses, requiring immunosupressive treatment with vincrisine, prednisone, or rituximab. The patient with aplastic anemia died of pulmonary hypertension 5 y after bone marrow transplantation. All other 11 patients are alive and free of TTP for a median follow-up of 12 mo (range, 3-72 mo).

CONCLUSIONS

Acquired pediatric TTP responds well to plasmapheresis. However, many patients do require additional treatment because of refractoriness to plasmapheresis or relapse. The clinical features, response to treatment, and relapse rate of pediatric TTP appear similar to those of adult TTP.

Deficiency of ADAMTS-13 in pediatric patients with severe sepsis and impact on in-hospital mortality

BACKGROUND

The enzyme involved in regulating the size of vWF (von Willebrand factor) in plasma is ADAMTS-13 (A disintegrin and metalloprotease with thrombospondin type-1 motives). Deficient proteolysis of ULvWF (ultra large von Willebrand factor) due to reduced ADAMTS-13 activity results in disseminated platelet-rich thrombi in the microcirculation characteristic of thrombotic thrombocytopenic purpura. Reduced ADAMTS-13 has also been observed in severe sepsis and is associated with poor survival. We conducted this study to detect ADAMTS-13 deficiency and its impact on in-hospital mortality in pediatric patients with severe sepsis.

METHODS

Pediatric patients diagnosed with severe sepsis were recruited for the study. Baseline clinical characteristics were noted. ADAMTS-13 antigen levels were assayed by ELISA. According to ADAMTS-13 levels, patients were grouped as deficient and non-deficient. Comparison was done with regard to some clinical and biological characteristics and in-hospital mortality between the two groups.

RESULTS

A total of 80 patients were enrolled in the study. The median age of the patients was 3.1 years (Range: 0.1-15 years). ADAMTS-13 deficiency with levels less than 350 ng/dl was found in 65% patients. In patients with ADAMTS-13 deficiency, 75.6% had low platelets of less than 150 × 109/L. In-hospital mortality was 42.3% and 35.7% in ADAMTS-13 deficient and non-deficient group, respectively.

CONCLUSION

Majority of the pediatric patients admitted to hospital with severe sepsis exhibit ADAMTS-13 deficiency. ADAMTS-13 deficiency might play a role in sepsis-induced thrombocytopenia. More studies are needed to evaluate the role of ADAMTS-13 deficiency on in-hospital mortality.

Low-dose rituximab for the treatment of acute thrombotic thrombocytopenic purpura: report of four cases

OBJECTIVE AND IMPORTANCE

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder that needs prompt diagnosis and treatment. Front-line therapy consists of plasma exchange (PEx) and steroids, but, in some instances, this is not enough to achieve a complete and sustained response.

CLINICAL PRESENTATION

We report four cases of TTP treated with low-dose rituximab, PEx, and a short course of steroids with an excellent outcome. Three of the patients had primary TTP and another presented an underlying human immunodeficiency virus infection.

INTERVENTION

Rituximab, 100 mg intravenously, was initiated on days 2-8 from the start of PEx as first-line therapy in three cases and as salvage therapy for relapsing disease in one. The number of PEx needed ranged from 5 to 12 sessions. All patients achieved complete remission and are currently asymptomatic, with complete response duration of 8-22 months.

CONCLUSION

Treatment of TTP with low-dose rituximab, along with PEx and steroids, seems to be as effective as the standard dose of monoclonal antibody.

Anemias beyond B12 and iron deficiency: the buzz about other B's, elementary, and nonelementary problems

The term “unexplained anemia” appears frequently in a request for a hematology consultation. Although most anemia consultations are fairly routine, they occasionally represent challenging problems that require an amalgam of experience, insight, and a modicum of “out-of-the-box” thinking. Problem anemia cases and pitfalls in their recognition can arise for one of several reasons that are discussed in the cases presented herein. “Anemias beyond B12 and iron deficiency” covers a vast domain of everything that lies beyond the commonly encountered anemias caused by simple deficiencies of 2 currently major hematologically relevant micronutrients. However, even these deficiencies may be obscured when they coexist or are not considered because of misleading distractions. They may also be mistakenly identified when other less common nutrient deficiencies occur. I present herein case examples of such situations: a young patient with pancytopenia and schistocytes who was responsive to plasmapheresis, but in whom pernicious anemia was not suspected because of ethnicity and age; a bicytopenic patient with anemia and myelodysplastic features caused by copper deficiency after gastric reduction surgery; and a patient with BM hypoplasia and a dimorphic blood smear who was found to have paroxysmal nocturnal hemoglobinuria. These “pearls” represent but 3 examples of the many varieties of problems in anemia diagnosis and are used to illustrate potential pitfalls and how to avoid them.

Cyclosporin A therapy on idiopathic thrombotic thrombocytopenic purpura in the relapse setting: two case reports and a review of the literature

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disease, characterized by microangiopathic hemolytic anemia, thrombocytopenia, fever, neurologic disturbances, and renal failure. Plasma therapy has dramatically improved prognosis of TTP, whereas recurrent acute episodes still occur in approximately 40% of patients. Moreover, patients with acquired ADAMTS13 deficiency, which is a significant factor for relapse, may require additional immunosuppressive treatment to get a durable remission.

STUDY DESIGN AND METHODS

We hereby report two patients with a history of relapsed idiopathic TTP, who both received cyclosporin A (CSA) as a prophylactic manner after the remission was achieved. We also discuss the efficacy of CSA in patients with relapsed idiopathic TTP with a review of the published literature.

RESULTS

Under CSA therapy, both patients maintained their clinical remission state, and the ADAMTS13 levels were normalized.

CONCLUSION

To conclude, CSA therapy may be useful for the prevention of relapsed idiopathic TTP in patients with a history of frequent relapses.

Thrombotic microangiopathy and associated renal disorders

Thrombotic microangiopathy (TMA) is a pathological process involving thrombocytopenia, microangiopathic haemolytic anaemia and microvascular occlusion. TMA is common to haemolytic uraemic syndrome (HUS) associated with shiga toxin or invasive pneumococcal infection, atypical HUS (aHUS), thrombotic thrombocytopenic purpura (TTP) and other disorders including malignant hypertension. HUS complicating infection with shiga toxin-producing Escherichia coli (STEC) is a significant cause of acute renal failure in children worldwide, occurring sporadically or in epidemics. Studies in aHUS have revealed genetic and acquired factors leading to dysregulation of the alternative complement pathway. TTP has been linked to reduced activity of the ADAMTS13 cleaving protease (typically with an autoantibody to ADAMTS13) with consequent disruption of von Willebrand factor multimer processing. However, the convergence of pathogenic pathways and clinical overlap create diagnostic uncertainty, especially at initial presentation. Furthermore, recent developments are challenging established management protocols. This review addresses the current understanding of molecular mechanisms underlying TMA, relating these to clinical presentation with an emphasis on renal manifestations. A diagnostic and therapeutic approach is presented, based on international guidelines, disease registries and published trials. Early treatment remains largely empirical, consisting of plasma replacement/exchange with the exception of childhood STEC-HUS or pneumococcal sepsis. Emerging therapies such as the complement C5 inhibitor eculizumab for aHUS and rituximab for TTP are discussed, as is renal transplantation for those patients who become dialysis-dependent as a result of aHUS.

Thrombotic microangiopathy: current knowledge and outcomes with plasma exchange

The classification of thrombotic microangiopathy has evolved and expanded due to treatment and mechanistic advances. The two basic clinical forms of thrombotic microangiopathy (excluding disseminated intravascular coagulation [DIC]), thrombotic thrombocytopenic purpura (TTP), and hemolytic uremic syndrome (HUS) encompass a wide range of primary and secondary forms. The advent of plasma therapy and the identification of an inhibitor to ADAMTS13 in the idiopathic or acute forms of TTP and its absence in diarrheal HUS have had a major impact on our current classification of thrombotic microangiopathy. In adults, the difficulty of differentiating TTP, which is much more common than HUS and the need for a speedy diagnosis to provide life-saving plasma therapy has resulted in the term TTP/HUS for adult forms of thrombotic microangiopathy that present with unexplained thrombocytopenia and microangiopathic hemolytic anemia without a DIC. In this adult population a primary idiopathic and hereditary form as well as eight known secondary categories or clinical forms of TTP/HUS have been identified. HUS also embraces a primary (atypical HUS) and secondary forms (majority, diarrheal HUS secondary to Escherichia coli 0157:H7). In children, who present with HUS with no preceding history of diarrhea, plasma therapy is also offered on an urgent basis and studies are carried out to determine if they are suffering an abnormality in complement activation that may require eculizumab therapy. The advent of plasma therapy in the treatment of thrombotic microangiopathy has led to a clearer understanding of the role of ADAMTS13, both short- and long-term outcomes and the need for future surveillance and intervention.

Advantages and limits of ADAMTS13 testing in the prognostic assessment of thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a rare but severe disease characterized by mechanical hemolytic anemia and consumptive thrombocytopenia leading to disseminated microvascular thrombosis that causes signs and symptoms of organ ischemia and functional damage. After the elucidation of the pathophysiology of TTP, thanks to the demonstration of the congenital or acquired (autoimmune) plasma deficiency of the von Willebrand factor cleaving metalloprotease A Disintegrin And Metalloprotease with ThromboSpondin 1 repeats (ADAMTS13), a number of laboratory assays for measuring ADAMTS13 and related autoantibodies have been developed. Current knowledge on the diagnostic and prognostic value of ADAMTS13 and anti-ADAMTS13 assays is summarized in this review.

Rituximab therapy for autoimmune haematological diseases

Autoimmune haematological diseases are characterized by the production of antibodies against blood proteins or cells, and comprise primary immune thrombocytopenia, autoimmune haemolytic anaemia, acquired haemophilia, and thrombotic thrombocytopenic purpura. Current treatments for these disorders include corticosteroids, cytotoxic drugs and splenectomy, which may be associated with significant systemic toxicity and/or morbility. B cells play a key role in both the development and perpetuation of autoimmunity, since they produce autoantibodies but also function as antigen-presenting cells, and release immunomodulatory cytokines. Rituximab, an anti-CD20 monoclonal antibody that specifically depletes B cells, may be an effective treatment strategy for patients with autoimmune disorders. This article reviews data of the literature, showing that patients with autoimmune haematological diseases can respond to rituximab irrespective of age and number or type of prior treatments. These data suggest that rituximab provides an effective and well-tolerated treatment option for these conditions.

ADAMTS13 gene mutations in children with hemolytic uremic syndrome

We investigated ADAMTS13 activity as well as the ADAMTS13 gene mutation in children with hemolytic uremic syndrome (HUS). Eighteen patients, including 6 diarrhea- negative (D-HUS) and 12 diarrhea-associated HUS (D+HUS) patients, were evaluated. The extent of von Willebrand factor (VWF) degradation was assayed by multimer analysis, and all exons of the ADAMTS13 gene were PCR-amplified using Taq DNA polymerase. The median and range for plasma activity of ADAMTS13 in 6 D-HUS and 12 D+HUS patients were 71.8% (22.8-94.1%) and 84.9% (37.9-119.9%), respectively, which were not statistically significantly different from the control group (86.4%, 34.2-112.3%) (p>0.05). Five ADAMTS13 gene mutations, including 2 novel mutations [1584+2T>A, 3941C>T (S1314L)] and 3 polymorphisms (Q448E, P475S, S903L), were found in 2 D-HUS and one D+HUS patients, which were not associated with deficiency of ADAMTS13 activity. Whether these mutations without reduced ADAMTS13 activity are innocent bystanders or predisposing factors in HUS remains unanswered.

Concurrent thrombotic thrombocytopenic purpura and immune thrombocytopenic purpura in a patient with metastatic neuroendocrine tumour successfully treated with rituximab-CVP

We report a case of concurrent thrombotic thrombocytopenic purpura (TTP) and immune thrombocytopenic purpura (ITP) in a 63-year-old woman who had been receiving treatment with bevacizumab for metastatic neuroendocrine tumour (NET). At diagnosis, she had severe anaemia and thrombocytopenia with elevated lactate dehydrogenase and many schistocytes on the peripheral blood smear. She was treated with frequent fresh frozen plasma infusions and plasmapheresis with poor response. Later, she was found to have platelet surface glycoprotein antibodies in the serum and received four cycles of rituximab, vincristine, cyclophosphamide (rituximab-CVP) and steroids in addition to plasma therapy. The haemoglobin and platelet counts improved. To our knowledge, this is the first reported case of concurrent TTP and ITP in a patient with metastatic NET diagnosed while receiving bevacizumab therapy, who was successfully treated with the combination of rituximab, vincristine, cyclophosphamide and steroids.

A 9-month-old infant with acquired idiopathic thrombotic thrombocytopenic purpura caused by inhibitory IgG-autoantibody to ADAMTS13

Although acquired idiopathic thrombotic thrombocytopenic purpura (ai-TTP) is rare in children, the authors present the case of a 9-month-old boy with ai-TTP showing severe deficiency of ADAMTS13 activity by its inhibitory IgG-autoantibody (4.8 Bethesda units/mL). Plasma exchange therapy was clinically effective but transient. Deficient activity of ADAMTS13 with the presence of its inhibitor persisted for 7 months after the initial diagnosis. However, other laboratory findings improved gradually with steroid (pulse) therapy. The hitherto insufficiently characterized clinical settings of ai-TTP during early childhood underscore the importance of measuring ADAMTS13 activity and its inhibitors for differential diagnosis in patients with thrombocytopenia of unknown etiology.

High versus standard dose methylprednisolone in the acute phase of idiopathic thrombotic thrombocytopenic purpura: a randomized study

Therapeutic plasma exchange (PE) is the accepted therapy for thrombotic thrombocytopenic purpura (TTP). Because not all patients achieve remission, other treatment modalities have been used in addition to PE, but no randomized clinical trial evaluated their efficacy. The aim of this multicentric study was to compare the effectiveness of standard- versus high-dose methylprednisolone as an adjunctive treatment to PE in the acute phase of TTP. Sixty patients with idiopathic TTP were randomized to receive methylprednisolone 1 mg/kg/die intravenous or 10 mg/kg/die for 3 days, thereafter, 2.5 mg/kg/die in addition to PE. Both dosages of steroids were well tolerated. At the end of induction therapy (day 23), the percentage of patients failing to achieve complete remission was significantly higher in the standard dose (16 of 30) than in the high-dose group (seven of 30). Also, the number of cases without a good response at day 9 and the number of deaths were higher in the standard-dose arm, but the differences did not reach the statistical significance. Results of present study indicate that the association of PE with high-dose instead of standard-dose steroids reduces the percentage of TTP patients that fail to achieve complete remission.

Effect of prophylactic cyclosporine therapy on ADAMTS13 biomarkers in patients with idiopathic thrombotic thrombocytopenic purpura

Several reports have been published regarding the use of cyclosporine (CSA) in the treatment of idiopathic thrombotic thrombocytopenic purpura (TTP). We hypothesized that prophylactic CSA therapy may prevent recurrences in patients with a history of multiple relapses of TTP. Nineteen patients with idiopathic TTP were enrolled on prospective studies at Ohio State University between September 2003 and May 2007. Patients achieving remission remained on CSA therapy for 6 months, allowing us to evaluate the efficacy of CSA as prophylactic therapy. CSA was administered orally at a dose of 2-3 mg/kg in twice a day divided dose in all patients and continued for a total of 6 months. Long-term clinical follow-up with serial analysis of ADAMTS13 biomarkers during and after CSA therapy were performed to evaluate the efficacy of CSA as a prophylactic therapy. 17/19(89%) patients completed 6 months of CSA therapy in a continuous remission. Two patients relapsed during therapy with CSA and seven patients relapsed after discontinuing CSA therapy. Ten patients have maintained a continuous remission a median of 21 months (range, 5-46) after discontinuing CSA. The ADAMTS13 data suggest that CSA resulted in a significant increase in the ADAMTS13 activity during therapy with CSA. 8/9(89%) relapsing patients had severely deficient ADAMTS13 activity (<5%) suggesting this is a significant risk factor for relapse of TTP. These data support the hypothesis that prophylactic CSA improves the ADAMTS13 activity and may be effective at preventing relapses in patients at risk for recurrences of TTP.

Von Willebrand factor, ADAMTS13, and thrombotic thrombocytopenic purpura

Discoveries during the past decade have revolutionized our understanding of idiopathic thrombotic thrombocytopenic purpura (TTP). Most cases in adults are caused by acquired autoantibodies that inhibit ADAMTS13, a metalloprotease that cleaves von Willebrand factor within nascent platelet-rich thrombi to prevent hemolysis, thrombocytopenia, and tissue infarction. Although approximately 80% of patients respond to plasma exchange, which removes autoantibody and replenishes ADAMTS13, one third to one half of survivors develop refractory or relapsing disease. Intensive immunosuppressive therapy with rituximab appears to be effective as salvage therapy, and ongoing clinical trials should determine whether adjuvant rituximab with plasma exchange also is beneficial at first diagnosis. A major unanswered question is whether plasma exchange is effective for the subset of patients with idiopathic TTP who do not have severe ADAMTS13 deficiency.