Thrombotic thrombocytopenic purpura: evidence that infusion rather than removal of plasma induces remission of the disease

Thrombotic thrombocytopenic purpura: A case report and review of literature

Introduction: Thrombotic thrombocytopenic purpura (TTP) is a syndrome that consists of the pentad of thrombocytopenia, microangiopathic hemolytic anemia, neurologic abnormalities, fever and renal disease. Moskowitz was the first who described this syndrome in 1925, finding hyaline thrombi in many organs. The microthrombi cause tissue ischemia, platelet consumption, and microangiopathic hemolytic anemia. Brain involvement is common and leads to stroke, seizure, confusion, and headache. Renal injury occurs in a minority of patients and it is usually modest. Case report: We present a 57-year old male who came to our hospital because of weakness, prostration and darkening of his urine, occurring several days before admission. On physical examination we found icteric coloring of his skin and conjunctiva, big hematoma on his right lower leg and he had neurological abnormalities presented as mild headache, disorientation and aphasia. Laboratory tests revealed anemia and thrombocytopenia and the examination of peripheral blood smear showed presence of schistocytes. Direct and indirect antiglobulin test (Coombs) was negative. Emergency treatment was started with plasmapheresis on daily basis, immunosuppressive treatment with high-dose methylprednisolone and transfusions of red blood cells. The laboratory results and the clinical condition improved within two weeks. Conclusion: TTP is a medical condition that can be fatal if emergency treatment with plasmapheresis is not initiated presently after suspected diagnosis.

Thrombotic thrombocytopenic purpura: a case presenting with acute ischemic colitis

Thrombotic thrombocytopenic purpura (TTP) consists of the pentad of thrombocytopenia, hemolytic anemia, fever, neurologic abnormalities, and renal disease. We present a case report of acute TTP following a bout of ischemic colitis. This report reminds the clinician that ischemic colitis can be an atypical presentation of TTP. The prompt recognition and treatment of this disease process resulted in a good prognosis for our patient.

Twice-daily plasma exchange for patients with refractory thrombotic thrombocytopenic purpura: the experience of the Oklahoma Registry, 1989 through 2006

BACKGROUND

Twice-daily plasma exchange has been used for patients with thrombotic thrombocytopenic purpura (TTP) who are unresponsive to treatment with daily plasma exchange for many years but with no clear evidence of effectiveness.

STUDY DESIGN AND METHODS

The 18 years' experience of The Oklahoma TTP-HUS (hemolytic-uremic syndrome) Registry, 1989 through 2006, with twice-daily plasma exchange for 31 episodes of TTP in 28 patients is reported. A definite response to twice-daily plasma exchange was defined a priori as a platelet (PLT) count increase after twice-daily plasma exchange on two separate occasions during the treatment of a single episode of TTP, with no change of other treatments. A possible response was defined as a PLT count increase after initiation of twice-daily plasma exchange only once with or without change of other treatments.

RESULTS

A definite response to twice-daily plasma exchange occurred in 3 episodes (three patients), 27 episodes had a possible response, and 1 episode had no response. The three patients with a definite response had ADAMTS13 activities of 5, 6, and 12 percent and all had an inhibitor; the patient with no response was subsequently determined to have Rocky Mountain spotted fever.

CONCLUSION

Twice-daily plasma exchange was typically considered in acutely ill patients who had initially responded but then severe thrombocytopenia recurred, often with new neurologic abnormalities, while continuing daily plasma exchange. In three patients, twice-daily plasma exchange appeared to be beneficial. In most patients, a benefit of twice-daily plasma exchange could not be clearly documented because other treatments were initiated or intensified.

Thrombotic thrombocytopenic purpura in a patient with Brucella infection is highly responsive to combined plasma infusion and antimicrobial therapy

OBJECTIVE

To report a case of brucella infection presenting with thrombotic thrombocytopenic purpura (TTP) that responded well to plasma and antimicrobial treatment infusion.

CASE PRESENTATION AND INTERVENTION

A 51-year-old man with moderate confusion, depressed mood and dysarthria was admitted. He was chronically ill, with fever (38.5 degrees C), anemia, jaundice and petechial-purpuric skin lesions. Neurological examination revealed diminished consciousness with a Glasgow coma scale score of 7 and +1 neck rigidity. The hemoglobin and platelet counts were decreased and reticulocyte index, erythrocyte sedimentation rate, as well as serum lactate dehydrogenase and renal dysfunction were elevated. TTP was a possible diagnosis and the patient responded well to plasma infusion and antimicrobial treatment.

CONCLUSION

This report shows that therapy of underlying infection together with plasma infusion may be a successful treatment option for brucellosis-induced TTP.

Time course of organ dysfunction in thrombotic microangiopathy patients receiving either plasma perfusion or plasma exchange

INTRODUCTION

Few studies have investigated adults with thrombotic microangiopathy (TMA) requiring intensive care unit (ICU) admission, and the treatment remains controversial.

OBJECTIVE

To describe causes, outcomes, prognostic factors, and daily organ-failure score changes in adults with TMA requiring ICU admission.

DESIGN

A 3-yr single-center cohort study.

PATIENTS

The patients were 36 adults with TMA admitted to a teaching-hospital medical ICU between January 2000 and June 2003.

RESULTS

Of the 36 patients, 22 received plasma infusion and 15 underwent plasma exchange. All patients had anemia and thrombocytopenia at ICU admission, and 13 had neurologic impairment. Median creatinine clearance was 55.2 mL/min (interquartile range, 28.8-75.4). No patient had congenital TMA. Causative factors included microbiologically documented infection in 14 patients, allogeneic transplantation in 7 patients, and concomitant or subsequent systemic disease in 7 patients; 6 patients were human immunodeficiency virus-positive, 5 had drug-induced TMA, 2 were pregnant, and 2 had cancer. In 10 patients, no causative factors were identified. Plasma exchange was associated with a statistically significant decrease in hospital mortality (0 vs. 7 deaths; p < .001). Moreover, daily organ-failure scores were significantly lower in the plasma-exchange group from day 3 to day 9. Patients in the plasma-exchange group received a larger volume of plasma.

CONCLUSION

Plasma exchange may be associated with faster resolution of organ failure and with improved survival for patients with TMA requiring ICU admission.

The hemolytic uremic syndromes

PURPOSE OF REVIEW

Recent studies have provided a better understanding of the molecular mechanisms responsible for hemolytic uremic syndromes. In this review, we summarize biochemical and genetic data that may lead to new clinical approaches.

RECENT FINDINGS

The structures and modes of action of Shiga toxins have been deciphered. Patients with non-Shiga-like toxin hemolytic uremic syndrome have been found to carry mutations in three genes that encode for regulators of the complement system (factor H, membrane cofactor protein, and factor I).

SUMMARY

Shiga-like toxin-1 and Shiga-like toxin-2 regulate genes that encode for chemokines, cytokines, cell adhesion molecules, and transcription factors involved in immune response and apoptosis. Mutations in factor H, membrane cofactor protein and factor I have recently been identified. Reduced expression of compliment regulators might prevent restriction of complement deposition on glomerular endothelial cells, leading to microvascular cell damage and tissue injury. Shiga-like toxin hemolytic uremic syndrome in children has a favorable prognosis in 90% of cases; kidney transplantation shows a good graft survival rate (80%) in children who progress to end stage renal disease. As for non-Shiga-like toxin hemolytic uremic syndrome, treatment with plasma infusion or exchange has been used with controversial effects. Kidney transplantation is not recommended in those patients with mutations in factor H and factor I; however, a kidney transplant corrects membrane cofactor protein dysfunction. These findings vividly underscore the clinical heterogeneity of outcomes depending upon the nature of the underlying cause of the disease.

Évolution des indications et de la consommation du plasma frais congelé de 1997 à 2003 dans un hôpital universitaire

OBJECTIVE

Study the evolution for 7 years of the distribution of fresh frozen plasma consumptions (FFP) according to the therapeutic indications.

MATERIALS AND METHODS

Introduction in the software of the blood bank of a specific character during the distribution of all the homologous FFP allowing a selective sort of the consumptions of FFP according to their therapeutic indications. These "qualifying terms" are defined in function, not only of the French legal references (issued on 3 December 1991),--consumption coagulopathy--global or specific deficit in coagulation factor, but also according to the specificities of our health care institution (liver transplant--thrombotic microangiopathies--open heart surgery).

RESULTS

During 7 years, the consumption of FFP trebled in our institution. The indications of the FFP are now mainly medical, its use in surgery dramatically decreased. The complications are not very frequent, most of them are slight allergic reactions.

CONCLUSION

New therapies, molecules coming from the research, recombinant proteins or coming from the plasma fractionation will certainly modify the indications of the fresh plasma frozen in the coming years. The supervision of our practices remains essential.

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.

Infectious diseases as a trigger in thrombotic microangiopathies in intensive care unit (ICU) patients?

OBJECTIVE

Thrombotic microangiopathy (TMA) has been associated with a large number of underlying diseases. We conducted a descriptive, retrospective study including all TMA adult patients admitted to our ICU, with a particular interest in infectious episodes as a trigger of TMA.

PATIENTS

All adult patients (30) with a diagnosis of TMA admitted to the medical ICU at Saint-Louis Hospital (Paris, France) between 1992 and 1998 were retrospectively included.

METHODS

All patients with clinical and microbiological evidence of bacterial infection were treated with intravenous antibiotics. The specific treatment of TMA consisted in solvent/detergent-treated plasma administration by plasma exchange or high volume plasma infusion (30 ml/kg per day) in fractionated doses.

RESULTS

Among the 30 adult patients studied, TMA in 16 (53%) was associated with microbiologically documented infection. An acute infection was found in 8/9 patients with an HIV-related TMA, in 2/6 patients with a systemic lupus erythematosus (SLE)-related TMA and in 3/6 patients with TMA associated with other disorders. In three patients, an acute infectious disease was the only cause associated with the TMA. Four other patients had clinical manifestations suggesting an infection process but without bacteriological documentation. Escherichia coli was isolated in 7/16 cases and verotoxin was found in the stools of two other patients. All patients were treated with plasma administration and those with evidence of infection were systematically and intensively treated with antibiotics. Eventually 8 patients died (27%), 20 (67%) reached complete remission and 2 partial remission.

CONCLUSION

Bacterial infections are commonly observed amongst TMA patients hospitalized in ICUs and may act as a trigger of this disease. Screening for infection is a requirement in patients with TMA, either idiopathic or associated with other conditions.

High-dose plasma infusion versus plasma exchange as early treatment of thrombotic thrombocytopenic purpura/hemolytic-uremic syndrome

Thrombotic thrombocytopenic purpura and adult hemolytic-uremic syndrome (TTP/HUS) have a substantial mortality rate even with currently available treatments. Although therapeutic plasma exchange is the recommended treatment of TTP/HUS, this cumbersome procedure may not be available for all patients in an emergency. In this context, plasma infusion may represent an alternative first-line therapy. We compared the effectiveness of high-dose plasma infusion (25-30 mL/kg per day) and therapeutic plasma exchange as first-line treatment of adult TTP/HUS at a single center. Two groups of patients with TTP/HUS were identified according to their initial therapy, that is, high-dose plasma infusion (19 patients) and therapeutic plasma exchange (18 patients). Clinical charts and outcomes were retrospectively analyzed. Endpoints for comparison were the duration of platelet counts below 150 x 10 /L and LDH levels above normal values; the volumes of plasma administered and the duration of treatment; complete remission, relapse, and mortality rates; and treatment-related complications. Patients of the 2 groups had comparable clinical and laboratory features on admission. Sixteen patients achieved complete remission in each group. Median times to recovery of platelet counts and LDH levels were comparable between the 2 groups. Eight patients in the high-dose plasma infusion (HD-PI) group were switched to therapeutic plasma exchange because of fluid overload (6 patients), persistent biologic disturbances (1 patient), or unresponsiveness to high-dose plasma infusion treatment (1 patient). This latter patient had severe TTP/HUS that remained refractory to therapeutic plasma exchange and vincristine, and rapidly died. All 7 remaining patients achieved complete remission with therapeutic plasma exchange. Four patients in the HD-PI group and 3 patients in the therapeutic plasma exchange (TPE) group died. In the HD-PI group, 5 patients experienced a transient nephrotic-range proteinuria during treatment. Main complications in the TPE group were collapse (1 patient) and central venous catheter infection (2 patients) or thrombosis (1 patient). Three patients in each group relapsed. High-dose plasma infusion may be an efficient treatment of TTP/HUS in patients who cannot have early plasma exchange. However, the large volumes of plasma required to reach complete remission may result in fluid overload, which may necessitate subsequent therapeutic plasma exchange.

Thrombotic microangiopathies

The thrombotic microangiopathies (TMA) are a group of diseases associated with microangiopathic hemolytic anemia, thrombocytopenia, and end-organ dysfunction. These seemingly disparate entities share in common a pathogenic mechanism involving endothelial injury and thrombus formation. Prognosis and treatment depend on the nature of the underlying disease.

Intracranial hemorrhage at the onset of thrombotic thrombocytopenic purpura in an infant: therapeutic approach and intensive care management

Thrombotic thrombocytopenic purpura (TTP) is quite rare in infancy and must be treated intensively as a life-threatening disease. Diffuse vascular thromboses may occur, and neurologic involvement is a cornerstone of the diagnosis of TTP. We describe a case of an infant who presented with a sudden cerebral hemorrhage and subsequently developed the typical clinical features of TTP. Emergency treatment in the Pediatric Intensive Care Unit (PICU) consisted of plasma therapy and exchange-transfusion (EXT) to arrest the intravascular process and the exsanguinating blood loss. Exchange-transfusion is a life-saving procedure that is rarely performed after the neonatal age.

The management of idiopathic thrombotic microangiopathy. Changing trends

Thrombotic microangiopathy, including the two related syndromes thrombotic thrombocytopenic purpura and hemolytic-uremic syndrome, is a rare and severe multisystem disorder, due to widespread deposition of intravascular microthrombi consisting mainly of platelets, with subsequent consumption thrombocytopenia, microangiopathic hemolytic anemia, renal abnormalities, and neurologic disturbances. The epidemic, verotoxin-induced hemolytic-uremic syndrome, typically associated with prodromal diarrhea, mainly affects young children in small outbreaks. By contrast, idiopathic thrombotic microangiopathy generally affects adults in a sporadic form; it has a more devastating course and a less favourable outcome. Over 90% of the reported cases in the adult, when untreated, have progressed to death within three months of diagnosis. Since the introduction of plasma exchange, a dramatic change in the prognosis of the disease has taken place, although the mortality rate still remains considerable. Indeed, improved survival is the most striking feature of adult thrombotic microangiopathy compared to some decades ago. In the present article we will focus on the evolving concepts able to exert a considerable impact in the management of the adult idiopathic form of thrombotic microangiopathy.

A novel interpretation of the role of von Willebrand factor in thrombotic microangiopathies based on platelet adhesion studies at high shear rate flow

Clinical manifestations of thrombotic microangiopathies (TMA) are secondary to platelet aggregation and thrombotic occlusion of the microvasculature of the affected organs. Abnormalities in von Willebrand factor (vWF) in these patients were considered instrumental in promoting the process leading to microvascular thrombosis. We evaluated the capacity of plasma in these patients to induce adhesion of normal platelets and thrombus formation under conditions of controlled fluid shear stress. We also studied vWF multimeric distribution to establish whether abnormalities of this glycoprotein correlate with platelet adhesion and thrombus formation. Plasma from patients in the acute phase and remission showed the same capacity to induce platelet adhesion and thrombus formation at a low level of shear rate (600 sec(-1)) as plasma from control subjects. At a high shear rate (1,500 sec(-1)), platelet adhesion and thrombus dimensions were significantly increased (P: < 0.05) by plasma from patients with TMA compared with controls. The capacity to enhance thrombus formation at high shear stress was present during the acute phase and disease remission and did not correlate with the presence of unusually large vWF multimers. Increased thrombus formation with patient plasma is completely normalized by blocking the interaction of vWF with the platelet receptors, glycoprotein (GP)Ib and GPIIb-IIIa, suggesting that the phenomenon is completely mediated by vWF. Our results suggest the possibility of an intrinsically altered vWF molecule in these patients that is probably more effective than normal vWF in mediating platelet adhesion and thrombus formation.

Unrecognized pattern of von Willebrand factor abnormalities in hemolytic uremic syndrome and thrombotic thrombocytopenic purpura

Heterogeneous abnormalities in multimeric structure and fragmentation of endothelial-derived von Willebrand factor (vWF) have been reported in hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). This study was conducted to establish whether different patterns of vWF abnormalities were associated with different clinical syndromes. Plasmatic levels of vWF antigen (vWF:Ag), vWF release from endothelial cells (EC) exposed to patient sera, and vWF multimeric pattern were studied during episodes and again in remission in three groups of patients with severe forms of HUS and TTP paradigmatic of the most common clinical patterns of disease presentation: (1) plasma-responsive; (2) plasma-resistant; and (3) frequently relapsing. Plasma vWF:Ag and serum-induced vWF release from EC were increased in the acute phase of either plasma-responsive and plasma-resistant HUS and TTP, but normalized at remission only in plasma-responsive cases. Both indices were persistently normal in the relapsing forms. Enhanced vWF fragmentation as defined by disappearance of high molecular weight and increase in low molecular weight forms was a consistent finding of the acute phases, and always normalized in remission in all three groups. Unusually large vWF multimers were found exclusively in plasma of relapsing forms of HUS and TTP both during and between relapses. Enhanced levels of vWF:Ag and serum capability to induce vWF release in vitro are markers of disease activity and may reflect systemic endothelial injury and consequent activation. Their presence discriminates acute single-episode cases from relapsing forms and, when failing to normalize with plasma therapy, predicts plasma resistance. Enhanced low molecular weight multimers that closely paralleled disease activity suggest a permissive role of fragmented vWF in the formation of microvascular thrombi. Finally, finding of unusually large multimers exclusively in relapsing forms of HUS and TTP even between relapses, when no other clinical signs of disease activity could be detected, suggests that they cannot be the only factor in microvascular thrombosis.

Neutrophil Activation and Hemostatic Changes in Healthy Donors Receiving Granulocyte Colony-Stimulating Factor

Granulocyte colony-stimulating factor (G-CSF) enhances neutrophil functions in vitro and in vivo. It is known that neutrophil-derived products can alter the hemostatic balance. To understand whether polymorphonuclear leukocyte (PMN) activation, measured as PMN degranulation and phenotypical change, may be associated to hemostatic alterations in vivo, we have studied the effect of recombinant human G-CSF (rHuG-CSF) administration on leukocyte parameters and hemostatic variables in healthy donors of hematopoietic progenitor cells (HPCs). Twenty-six consecutive healthy donors receiving 10 μg/kg/d rHuG-CSF subcutaneously for 5 to 7 days to mobilize HPCs for allogeneic transplants were included in the study. All of them responded to rHuG-CSF with a significant white blood cell count increase. Blood samples were drawn before therapy on days 2 and 5 and 1 week after stopping rHuG-CSF treatment. The following parameters were evaluated: (1) PMN activation parameters, ie, surface CD11b/CD18 antigen expression, plasma elastase antigen levels and cellular elastase activity; (2) plasma markers of endothelium activation, ie, thrombomodulin (TM) and von Willebrand factor (vWF) antigens; (3) plasma markers of blood coagulation activation, ie, F1+2, TAT complex, D-dimer; and (4) mononuclear cell (MNC) procoagulant activity (PCA) expression. The results show that, after starting rHuG-CSF, an in vivo PMN activation occurred, as demonstrated by the significant increment of surface CD11b/CD18 and plasma elastase antigen levels. Moreover, PMN cellular elastase activity, which was significantly increased at 1 day of treatment, returned to baseline at day 5 to 6, in correspondence with the elastase antigen peak in the circulation. This change was accompanied by a parallel significant increase in plasma levels of the two endothelial and the three coagulation markers. The PCA generated in vitro by unstimulated MNC isolated from rHuG-CSF–treated subjects was not different from that of control cells from untreated subjects. However, endotoxin-stimulated MNC isolated from on-treatment individuals produced significantly more PCA compared with both baseline and control samples. All of the parameters were decreased or normal 1 week after stopping treatment. These data show that rHuG-CSF induces PMN activation and transiently affects some hemostatic variables in healthy HPC donor subjects. The clinical significance of these findings remains to be established.

Neutrophil Activation and Hemostatic Changes in Healthy Donors Receiving Granulocyte Colony-Stimulating Factor

Granulocyte colony-stimulating factor (G-CSF) enhances neutrophil functions in vitro and in vivo. It is known that neutrophil-derived products can alter the hemostatic balance. To understand whether polymorphonuclear leukocyte (PMN) activation, measured as PMN degranulation and phenotypical change, may be associated to hemostatic alterations in vivo, we have studied the effect of recombinant human G-CSF (rHuG-CSF) administration on leukocyte parameters and hemostatic variables in healthy donors of hematopoietic progenitor cells (HPCs). Twenty-six consecutive healthy donors receiving 10 μg/kg/d rHuG-CSF subcutaneously for 5 to 7 days to mobilize HPCs for allogeneic transplants were included in the study. All of them responded to rHuG-CSF with a significant white blood cell count increase. Blood samples were drawn before therapy on days 2 and 5 and 1 week after stopping rHuG-CSF treatment. The following parameters were evaluated: (1) PMN activation parameters, ie, surface CD11b/CD18 antigen expression, plasma elastase antigen levels and cellular elastase activity; (2) plasma markers of endothelium activation, ie, thrombomodulin (TM) and von Willebrand factor (vWF) antigens; (3) plasma markers of blood coagulation activation, ie, F1+2, TAT complex, D-dimer; and (4) mononuclear cell (MNC) procoagulant activity (PCA) expression. The results show that, after starting rHuG-CSF, an in vivo PMN activation occurred, as demonstrated by the significant increment of surface CD11b/CD18 and plasma elastase antigen levels. Moreover, PMN cellular elastase activity, which was significantly increased at 1 day of treatment, returned to baseline at day 5 to 6, in correspondence with the elastase antigen peak in the circulation. This change was accompanied by a parallel significant increase in plasma levels of the two endothelial and the three coagulation markers. The PCA generated in vitro by unstimulated MNC isolated from rHuG-CSF–treated subjects was not different from that of control cells from untreated subjects. However, endotoxin-stimulated MNC isolated from on-treatment individuals produced significantly more PCA compared with both baseline and control samples. All of the parameters were decreased or normal 1 week after stopping treatment. These data show that rHuG-CSF induces PMN activation and transiently affects some hemostatic variables in healthy HPC donor subjects. The clinical significance of these findings remains to be established.

Apheresis and the thrombotic thrombocytopenic purpura syndrome: current advances in diagnosis, pathophysiology, and management

Endeavors to optimize the management of thrombotic thrombocytopenic purpura (TTP) syndrome and improve mortality and relapse rates are hindered by its poorly understood pathophysiology. Variability in the application of therapeutic plasma exchange (TPE), including replacement fluid strategies, desirable endpoints in the platelet count, serum lactate dehydrogenase concentration, and the use of a TPE taper, limit comparisons among published studies. The diversity of adjunctive therapies such as antiplatelet agents, steroids, and splenectomy further clouds comparisons. Recent progress in the diagnosis, pathophysiology, and management of TTP syndrome are summarized. The possible role of occult infection and newly emerging associations such as ticlopidine therapy are discussed. Advances in possible pathogenic mechanisms, the rationale for different replacement fluids including the recently licensed solvent-detergent treated plasma, and progress in the apheresis management of TTP syndrome are presented.

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.

Increased von Willebrand factor binding to platelets in single episode and recurrent types of thrombotic thrombocytopenic purpura

Extensive microvascular platelet aggregation is characteristic of thrombotic thrombocytopenic purpura (TTP). Previous studies have indicated that abnormalities of von Willebrand factor (vWf) are often present in TTP patient plasma. There has not been previously any direct evidence linking these abnormalities to the process of intravascular platelet aggregation in TTP. We used flow cytometry to analyze the binding of vWf to single platelets, and the presence of platelet aggregates, in the blood of 4 children with chronic relapsing (CR) TTP and 5 adults with single episode or recurrent TTP. vWf on the single platelets of CRTTP patients at all time points studied was significantly increased compared to controls, and was increased further as platelet counts decreased to levels below 40,000/microl. The single episode and recurrent adult TTP patients had platelet aggregates in the blood, as well as increased vWf on single platelets, before therapy commenced and thereafter until recovery was in process. In the one unresponsive single episode TTP patient, vWf on single platelets remained elevated, and platelet aggregates persisted, until her death. The platelet alpha-granular protein, P-selectin, was not increased on the single platelets of most TTP blood samples, suggesting that it is vWf from plasma (rather than from alpha-granules) that attaches to platelet surfaces in association with platelet aggregation. These results suggest that vWf-platelet interactions are involved in the platelet clumping process that characterizes TTP.

Thrombotic syndromes and autoimmune diseases

Maintenance of blood flow involves the dynamic interactions between the endothelium, circulating cellular components, coagulation factors, and factors involved in fibrinolysis. Autoantibodies, inflammatory cytokines and other undefined triggers in a genetically predisposed person may lead to an imbalance in the equilibrium between the various hemostatic pathways resulting in potentially catastrophic thrombotic events. This article reviews the clinical manifestations and treatment of selected, potentially life-threatening thrombotic syndromes that may occur in association with autoimmune diseases. Special mention is made of thrombotic events associated with Behçet's syndrome.

Plasma exchange in a patient with postpartum HELLP syndrome

The case of a patient with HELLP syndrome, who was unresponsive to supportive management but successfully treated with plasma exchange, is presented. The significance of plasma exchange in the treatment of HELLP syndrome is discussed.

Increased nitric oxide formation in recurrent thrombotic microangiopathies: a possible mediator of microvascular injury

The term thrombotic microangiopathy (TMA) has been used extensively to encompass hemolytic uremic syndrome and thrombotic thrombocytopenic purpura, two syndromes of hemolytic anemia, and thrombocytopenia associated with renal or brain involvement or both. There is evidence that endothelial damage is a crucial feature in the sequence of events that precedes the development of microvascular lesions. More recent studies would suggest that endothelial dysfunction could be a consequence of neutrophil activation. Activated neutrophils generate superoxide anions (O2-) that, combining with endothelial-derived nitric oxide (NO), form the highly cytotoxic hydroxyl radical. Seven patients with recurrent forms of TMA and seven healthy volunteers were studied. Plasma concentrations of the NO metabolites, nitrites/nitrates, were elevated in the acute phase of TMA, indicating an increased NO synthesis in vivo. In addition, elevated serum concentrations of tumor necrosis factor, a potent inducer of endothelial NO synthase, were found in acute TMA. Serum from patients with acute TMA induced NO synthesis in cultured endothelial cells more than normal serum. Enhanced stimulatory activity was no longer found in the recovery phase. Release of O2- by neutrophils ex vivo was higher than normal in patients with acute TMA, but decreased in the recovery phase. Exactly the same trend was observed for plasma malondialdehyde and conjugated dienes, indicating that excessive oxygen radical formation in acute TMA is associated with increased lipid peroxidation. Thus, in recurrent forms of TMA, NO formation was increased as compared with controls. This was associated with signs of lipid peroxidation, likely the consequence of the interaction of NO with neutrophil-derived oxygen products.

Malignant vascular disease of the kidney: nature of the lesions, mediators of disease progression, and the case for bilateral nephrectomy

A case of thrombotic microangiopathy presenting as a hemolytic uremic syndrome complicated by untreatable hypertension and ultimately requiring bilateral nephrectomy is discussed. Severe hypertension and renal failure may complicate the course of vascular diseases of the kidney, including thrombotic microangiopathy, chronic hypertension, and scleroderma. Toxins, pressure stress, and immune material may trigger the initial injury to vascular endothelium. The malignant course of these renal vascular diseases seems linked to the severity of vascular injury. Endothelial injury manifests with swelling and detachment of endothelial cells from the basement membrane, expansion of the subendothelial space, and newly formed basement membrane-like material. In arterioles, endothelial injury precedes myointimal swelling and proliferation, leading to vascular lumina narrowing or obliteration and secondary glomerular ischemia, with glomerular tuft collapse and garland-like wrinkling and thickening of the capillary wall. Endothelial cell injury is very likely the common determinant of a cascade of events that lead to irreversible renal failure. When the initial insult (toxins, mechanical stress, antibodies) is promptly removed, lesions are self-limiting and the patient usually recovers. However, a severe insult persisting for some time can lead to chronic and irreversible vascular lesions that, through renal ischemia, trigger maximal activation of the renin angiotensin system with a brisk elevation in arterial blood pressure that may combine to further vascular injury and renal ischemia. Moreover, enhanced shear stress in the severely narrowed microcirculation, through abnormal von Willebrand factor processing, can also favor endothelial injury and platelet aggregation, which may further worsen the vascular lesions and sustain the microangiopathic process. Plasma manipulation, arteriolar vasodilators, and angiotensin-converting enzyme inhibitors normally control the vicious circle, but in few severe cases bilateral nephrectomy remains the last chance to save the patient's life.

Bilateral nephrectomy stopped disease progression in plasma-resistant hemolytic uremic syndrome with neurological signs and coma

Four women were admitted over three years because of anemia and renal failure. They had evidence of hemolytic uremic syndrome (HUS) with severe vascular involvement and glomerular collapse. Despite intensive plasma exchange, all patients developed neurologic signs (with seizures and coma in 2) and papilledema. Three developed refractory hypertension and three required dialysis. All patients had abnormal von Willebrand factor (vWF) fragmentation as reflected by decreased high molecular weight and increased low molecular weight vWF multimers in the circulation. Assuming that the disease was sustained by shear stress-induced abnormal vWF fragmentation in damaged renal microvasculature, bilateral nephrectomy was done. Surgery was followed within two weeks by complete hematologic and clinical remission consistently associated with the restoring of vWF fragmentation pathway to normal. We speculate that in HUS resistant to plasma exchange or infusion, removing the kidneys eliminates a major site of vWF fragmentation, which would limit platelet activation and protect patients from the further spreading of microvascular lesions.

Abnormally large von Willebrand factor multimers in Henoch-Schönlein purpura

Allergic vasculitis phenomena seem to be involved in Henoch-Schönlein purpura (HSP). Elevated plasma levels of von Willebrand factor (vWf) are a well recognized feature of vasculitis and have been taken as an indication of in vivo endothelial cell damage. Plasma factor VIII:C and vWf levels and vWf multimeric pattern were studied in 8 patients with HSP, during active disease and twice during the remission (3 and 9 months later). Plasma vWf multimeric composition was evaluated using low resolution gels which better resolve large vWf multimers. During active disease plasma factor VIII:C, vWf:Ag, and vWf:RCoF were normal in 5% of patients and increased in three, but in each patient, platelets appeared to aggregate at doses of ristocetin lower than in normals. Furthermore, all patients demonstrated the presence of abnormally large vWf multimers usually found only in platelets and endothelial cells. Three and 9 months later, during remission, in spite of the normalization of factor VIII:C and vWf levels, the abnormal multimers were still detectable, as well as hyper-responsiveness to ristocetin. These findings confirm that damage and/or perturbation of endothelial cells is associated with HSP. Moreover, the persistence of abnormality in the vWf multimeric pattern, when the disease is inactive, suggests that the mechanisms involved operate through the entire clinical course.

Partial clinical improvement in Upshaw-Schulman syndrome following prostacyclin infusion

We report on a Japanese girl with Upshaw-Schulman syndrome, a congenital disorder characterized by recurrent thrombocytopenia, microangiopathic hemolytic anemia, proteinuria and hematuria that can be transiently improved by the transfusion of plasma or various plasma components. Unusually Large von Willebrand Factor (ULvWF) multimers were found during both relapse and remission phases. Serial plasma levels of 6-keto-prostaglandin F1 alpha (PGF1 alpha), the stable metabolite of prostacyclin (PGI2), were low at relapse. When the patient was treated with continuous PGI2 infusion, the microangiopathic hemolytic process gradually subsided within 10 days. These results suggest that PGI2 may be partly involved in the pathogenesis of this congenital disorder.

alpha 1-Antitrypsin therapy in a case of thrombotic thrombocytopenic purpura

In thrombotic thrombocytopenic purpura (TTP), activated leucocytes release elastase which mobilises unusually large von Willebrand factor (vWF) multimers from the endothelium. We investigated the effect of an inhibitor of leucocyte elastase (alpha 1-antitrypsin) on circulating vWF and platelet count in a patient with chronic relapsing TTP. alpha 1-antitrypsin consistently normalised vWF multimeric composition but failed to increase platelet count and induce remission. Plasma cryosupernatant, which never normalised vWF, always induced laboratory and clinical remission within 96 hours. In chronic relapsing TTP, unusually large vWF multimers are not the main cause of intravascular platelet aggregation.

Successful treatment of recurrent thrombotic thrombocytopenic purpura with plasmapheresis and vincristine

An adolescent girl with severe thrombotic thrombocytopenic purpura (TTP) remained in a critical condition after 3 weeks of combined treatment with antiplatelet drugs, plasma infusions and plasma exchange. The introduction of vincristine resulted in gradual improvement and eventual complete remission which lasted for 2 years. When she relapsed, immediate improvement was observed with the combined treatment of plasmapheresis and vincristine. She has now been in complete remission again for 10 months. It is suggested that plasmapheresis plus vincristine should be used as the initial treatment for children with TTP.

HELLP syndrome: laboratory parameters and clinical course in four patients treated with plasma exchange

We report our apheresis department's experience with four patients with HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome. The average age of the patients was 23.25 years (range 19-27). Three were in their second pregnancy while one was a primigravida. All had symptoms of pre-eclampsia prior to delivery. All experienced the syndrome postpartum. Plasma exchange was instituted an average of 3.25 days postpartum (range 1.08-7.33 days). All underwent plasmapheresis with fresh frozen plasma replacement. The average number of plasma exchange treatments was four (range 1-8). The first laboratory parameter to reach its peak/nadir was the aspartate aminotransferase (AST), followed by the lactate dehydrogenase (LDH) enzyme level, followed by the hemoglobin (HGB) level, and, finally, the platelet count (PLT). The AST was the first parameter to peak and the first to normalize. In the three cases in which more than one plasmapheresis procedure was performed, plasmapheresis was required for an average of 98 hours (range 39-206 hours) after a normal AST level was obtained in order to achieve a self-sustaining platelet count of > or = 100 x 10(9)/L. No additional exchanges were required to maintain the PLT once a PLT of over 100 x 10(9)/L was attained. The laboratory values normalized in the following order: AST, HGB, PLT, and LDH. Three patients were discharged anemic. One was discharged with a normal LDH level. By our experience, awaiting normal LDH levels as an indicator for cessation of plasma exchange therapy would mean subjecting the patients to many unnecessary procedures.(ABSTRACT TRUNCATED AT 250 WORDS)