Seminars in Hematology

Published by WB Saunders
Online ISSN: 0037-1963
Publications
Article
Suppression of normal hematopoiesis is a frequent complication of cancer or its treatment. The basis for dose-intensified cancer therapy in the 1990s was the discovery that hematopoietic growth factors and peripheral blood progenitor cell infusions can ameliorate some of its associated hematologic toxicities. Both granulocyte colony-stimulating factor and granulocyte macrophage colony-stimulating factor accelerate neutrophil recovery after chemotherapy and can mobilize peripheral blood progenitor cells for use in autologous or allogeneic transplantation. Unfortunately, the duration and severity of chemotherapy-induced thrombocytopenia is unaffected by the use of these myeloid growth factors. During the last 5 years, the activities of a variety of potential platelet or megakaryocyte-stimulating factors have been determined in clinical trials. The results of these studies are described.
 
Article
Fetal hemoglobin (HbF, alpha2gamma2) decreases polymerization of sickle hemoglobin, and high levels correlate with decreased morbidity and mortality in sickle cell disease (SCD). Therefore, a therapeutic goal for patients with SCD is pharmacologic reactivation of HbF. Decreased HbF production is associated with DNA methylation (by DNA methyltransferase [DNMT]) at the gamma-globin (HbF) gene promoter. The cytosine analogs 5-azacytidine and 5-aza-2'-deoxycytidine (decitabine) hypomethylate DNA by inhibiting DNMT. In early studies, 5-azacytidine produced significant HbF elevations in patients with thalassemia and SCD, but clinical development of this class of agent was halted after a poorly controlled animal study suggested that 5-azacytidine might be carcinogenic. However, the majority of preclinical studies with decitabine have suggested a chemopreventive rather than carcinogenic effect. Furthermore, decitabine, unlike 5-azacytidine, does not incorporate into RNA and is a more directed DNA-hypomethylating agent. Therefore, we have pursued studies of decitabine to pharmacologically reactivate HbF in patients with SCD. In phase I/II studies, decitabine at DNA-hypomethylating, but noncytotoxic, doses was well tolerated and effective at increasing HbF and total hemoglobin levels both in patients who had and had not responded to prior hydroxyurea therapy. In treated patients, there were marked improvements in a range of surrogate clinical endpoints measuring red blood cell adhesion, endothelial damage, and coagulation pathway activity. Pharmacologic reactivation of HbF through DNA hypomethylation holds promise as an effective disease-modifying intervention for patients with SCD. Larger studies are required to confirm the safety and effectiveness of decitabine with chronic use, and to more clearly establish its role in patients with SCD.
 
Article
Platelet activation and thrombus formation are key events in the pathogenesis of acute coronary syndromes (unstable angina and non-Q-wave myocardial infarction). Therefore, current management of these conditions consists of antithrombotic and antiplatelet therapy, principally heparin and oral aspirin. However, such treatment is unsuccessful in a significant proportion of patients. Two recent large studies with the low-molecular-weight heparin (LMWH) enoxaparin have shown that this agent significantly reduces the risk of major ischemic events compared with unfractionated heparin. In the Efficacy and Safety of Subcutaneous Enoxaparin in Non-Q-Wave Coronary Events (ESSENCE) study, treatment with enoxaparin for 2 to 8 days reduced the risk of death, myocardial infarction, or recurrent angina by 20% at 14 days compared with treatment with unfractionated heparin. In the Thrombolysis in Myocardial Infarction (TIMI) 11B study, enoxaparin was associated with a significant reduction in the risk of death, myocardial infarction, or urgent revascularization compared with unfractionated heparin, which became apparent within 48 hours; this benefit was maintained during outpatient treatment for 5 weeks. A meta-analysis of these two studies showed that the risk of death or myocardial infarction was consistently approximately 20% lower in enoxaparin-treated patients than in heparin-treated patients. In contrast, studies with other LMWHs have not shown consistent superiority over unfractionated heparin. This may reflect the pharmacologic heterogeneity of LMWH and/or differences in trial design.
 
Article
Severe deficiency of von Willebrand factor (VWF)-cleaving protease (ADAMTS-13) activity (<5% of normal) is a specific finding for acute idiopathic thrombotic thrombocytopenic purpura (TTP), a disorder that presents as thrombocytopenia, microangiopathic hemolytic anemia, and often organ dysfunction such as neurological disturbances or renal failure, and fever. Between January 2001 and July 2003, ADAMTS-13 activity was determined in plasma samples of 396 consecutive patients referred to our laboratory for diagnostic purposes. Plasma samples with ADAMTS-13 activity less than 5% were in addition tested for the presence of inhibitory antibodies. Patients were assigned to 10 predefined clinical categories according to information provided by the referring clinician: thrombotic microangiopathy (TMA) not further specified; neoplasia- or chemotherapy-associated TMA; TMA following hematopoietic stem cell transplantation; TMA with additional/alternative disorder; idiopathic TTP; hemolytic-uremic syndrome (HUS) not specified; HUS with diarrhea prodrome (D+HUS); atypical HUS; other hematological disorder; and no clinical information available. Severe ADAMTS-13 deficiency was found in 69 (17%) patients, including 42 with acquired idiopathic TTP, either at initial presentation or at relapse, 14 with confirmed or suspected hereditary TTP, 10 with TMA not further specified, two with neoplasia- or chemotherapy-associated TMA, and one in continued clinical remission 3.4 years after splenectomy for plasma-refractory TTP. Forty-three (62%) patients with ADAMTS-13 activity less than 5% displayed inhibitory antibodies. Severe ADAMTS-13 deficiency was found in 60% of patients diagnosed with acute idiopathic TTP, but in none of 130 patients diagnosed with HUS or in any of the 14 patients with hematopoietic stem cell transplantation-associated TMA. Thus, plasma ADAMTS-13 activity less than 5% does not identify all patients clinically diagnosed with TTP, and severe ADAMTS-13 deficiency is not invariably associated with clinical manifestations of microvascular platelet clumping.
 
Article
Thrombotic thrombocytopenic purpura (TTP) is a rare microangiopathic disorder with high morbidity and significant mortality. The primary form of TTP is caused by severe deficiency, acquired or hereditary, of the von Willebrand factor cleaving protease (VWF-CP), ADAMTS-13. Because TTP occurs less frequently in children, general pediatricians are not well informed about the spectrum of clinical symptoms and altered laboratory values, increasing the risk of nondiagnosis and possible fatal outcome. If renal involvement is present, the condition can easily be misdiagnosed as hemolytic-uremic syndrome (HUS). We present a case series of children with severe VWF-CP deficiency with emphasis on the clinical heterogeneity responsible for misdiagnosis and inappropriate treatment. The inherited form may involve onset of symptoms ranging from isolated thrombocytopenia to the full clinical picture characteristic of classical TTP. The most common assumed diagnoses of oligosymptomatic forms are immune thrombocytopenia (ITP) and Evans syndrome, respectively. Accordingly, this article is directed towards pediatricians on neonatal and intensive care units, as well as their colleagues specializing in nephrology, hematology, and neurology.
 
Article
Various assays for determination of ADAMTS-13 activity in plasma have been developed, all comprising two steps. The first step consists of proteolyzing a substrate by ADAMTS-13. Substrates were either exogenous von Willebrand factor (VWF) (purified from human plasma concentrates or recombinant VWF [rVWF]), purified VWF fragments, or endogenous VWF (from the tested plasma sample). All assays required a step in which substrate unfolding is performed using either urea or guanidine. Test plasmas were used at various dilutions and ADAMTS-13 was activated in most cases by divalent cations. The second step consists of quantifying the digestion products or the residual VWF remaining after proteolysis. Cleavage of VWF was thus estimated using electrophoresis (generation of proteolytic fragments or decrease of the size of multimers), functional methods (decrease of the collagen binding activity or of ristocetin cofactor activity), or immunological methods (enzyme-linked immunosorbent assay [ELISA] or immunoradiometric assay (IRMA) using selected monoclonal antibodies to VWF). Since 1998, all of these assays have been used to demonstrate the relevance of a deficient ADAMTS-13 activity in thrombotic thrombocytopenic purpura (TTP). However, improvements are required, as these methods remain cumbersome, time-consuming, and too remote from physiology to be routinely helpful for rapid laboratory diagnosis.
 
Article
Thrombotic thrombocytopenic purpura (TTP) is a severe, occlusive, microvascular "thrombotic microangiopathy" characterized by systemic platelet aggregation, organ ischemia, profound thrombocytopenia, and erythrocyte fragmentation. Failure to degrade "unusually large" (UL) von Willebrand factor (VWF) multimers as they are secreted from endothelial cells probably causes most cases of familial TTP, acquired idiopathic TTP, thienopyridine-related TTP, and pregnancy-associated TTP. The emphasis in this review is the pathophysiology of familial and acquired idiopathic TTP. In each of these entities, there is a severe defect in the function of a plasma enzyme, VWF-cleaving metalloprotease (ADAMTS-13), that normally cleaves hyper-reactive ULVWF multimers into smaller and less adhesive VWF forms. In familial TTP, mutations in the ADAMTS13 gene cause absent or severely reduced plasma VWF-cleaving metalloprotease activity. Acquired idiopathic TTP, in contrast, is the result in many patients of the production of autoantibodies that inhibit the function of ADAMTS-13. Established, evolving, and some of the unresolved issues in TTP pathophysiology will be summarized.
 
Article
Thrombotic thrombocytopenic purpura (TTP) is a severe disease associated with unusually large, hemostatically hyperactive von Willebrand factor (VWF) and severe deficiency in ADAMTS-13, the protease responsible for the proteolytic degradation of VWF in plasma. ADAMTS-13 prevents inappropriate microvascular platelet aggregation by cleaving VWF between Tyr1605 and Met1606 thereby producing dimers of 176 kd and 140 kd and smaller multimers. Identification of the ADAMTS13 gene and cloning of the corresponding cDNA allowed for the application of recombinant techniques, such as genetic engineering of ADAMTS13 cDNA, cell culture expression, and in vitro activity studies to analyze the functional relationship between ADAMTS-13 and the pathophysiology of ADAMTS-13 deficiency. In vitro expression and characterization of recombinant ADAMTS-13 (rADAMTS-13) clearly established that ADAMTS-13 is deficient in congenital TTP and inhibited in acquired TTP. Recent studies have contributed greatly to our current understanding of the molecular mechanism leading to congenital and acquired TTP. Apart from being a useful tool, availability of rADAMTS-13 raised the prospect of developing a recombinant substitution therapy to improve TTP treatment and allowing present diagnostic assays to be simplified. Here we report on recent advances in cell culture expression and functional characterization of human rADAMTS-13.
 
Article
When histamine-stimulated endothelial cells are perfused with platelets in buffer, the platelets form long beads-on-a-string structures on the surface of the cells. The strands connecting the platelets are composed of ultralarge multimers of von Willebrand factor (ULVWF) and can be rapidly cleaved when perfused with normal plasma or purified ADAMTS-13 metalloprotease, but not with plasma from patients with either congenital or acquired thrombotic thrombocytopenic purpura (TTP). These ULVWF strings anchor to the surface of the endothelial cell at least partly through P-selectin, as their formation is prevented by either soluble P-selectin or P-selectin antibodies. They are also able to support the attachment of beads coated with ADAMTS-13. The metalloprotease binds to both the A1 and A3 domains of VWF, the latter with higher affinity. This attachment docks the enzyme close to its substrate site within the A2 domain. We propose that attachment of newly released ULVWF to the endothelial cell surface facilitates its cleavage by ADAMTS-13 by allowing tensile force to be applied to the A2 domain, thereby exposing the ADAMTS-13 cleavage site.
 
Article
Based on clinical studies daily plasma exchange (PE) has become the first-choice therapy for thrombotic thrombocytopenic purpura (TTP) since 1991. Recent findings may explain its effectiveness, which particularly may include supply of ADAMTS-13 and removal of anti-ADAMTS-13 autoantibodies and unusually large von Willebrand factor (VWF) multimers. The most preferable PE regimens as well as replacement fluids are discussed and treatment-related adverse reactions are summarized. Proposals for a potential reduction of their frequency and for improvement of treatment efficiency are given. These suggestions are partially based on the experience of our institution in adult patients with severe ADAMTS-13 deficiency (<5% activity), and include (1) continuous calcium-gluconate infusion during PE in order to reduce citrate-related adverse reactions; (2) the evaluation of solvent/detergent-treated (S/D) plasma as replacement fluid in order to reduce adverse events due to fresh frozen plasma (FFP); (3) the evaluation of immunoadsorption in order to increase procedural efficiency in autoantibody removal; and (4) the substitution of ADAMTS-13 by means of recombinant drug instead of plasma.
 
Article
Many tumor cells are inherently resistant to curative treatment due to an altered pattern of gene expression. It is an attractive and logical proposition to use this difference within the lymphoma cell to eradicate the malignant process. One such new therapeutic approach based on the "silencing" of genes involved in the prevention of apoptosis is Bcl-2 antisense oligonucleotide (AO) therapy. In the field of lymphoma, obvious targets included follicular lymphoma with the t(15;18) translocation, which results in deregulated expression of the Bcl-2 gene, chemoresistance, and subsequent protection against lymphoma cell death. Targeting the initiating codon of the Bcl-2 gene decreases both cell viability and Bcl-2 protein expression in lymphoma and leukemia cell lines that overexpress Bcl-2. Preclinical toxicity studies using a Bcl-2 AO G3139 (Genta, San Diego, CA) show good tolerance at a dose of 10 mg/kg, which is considerably higher than the dose required for good antilymphoma efficacy. In a phase I clinical study, G3139 was well tolerated with minimal toxicity in a dose escalation up to 147.2 mg/m2/d. Evidence of efficacy includes a responder with stage IVB follicular lymphoma who achieved complete clinical and radiologic response that has lasted more than 2 years. The main dose-limiting toxicity has been reversible thrombocytopenia related to the thioate backbone. Other antisense reagents are also in development to combat non-Hodgkin's lymphoma (NHL). These include oligonucleotides that target the messages of the Bcl-X(L) and protein kinase-Calpha (PKCalpha) genes. AOs may also have an application in tumors expressing mutant p53. AOs against MDM2 genes have shown the ability to restore wild-type p53 expression, suggesting that as oncogenic pathways are unraveled, normal cell growth and death patterns may be restored by molecular manipulation. Downregulation of antiapoptosis by AOs in the human setting has low toxicity and antilymphoma activity in cases in which conventional chemotherapy has failed. In the future, antisense therapy followed by chemotherapy may overcome chemoresistance to provide effective therapy for a range of malignancies.
 
Article
The delineation of specific erythrocyte glycolytic enzyme defects during the past three decades has clarified hitherto unexplained hereditary hemolytic syndromes. The glycolytic enzymopathies have proven to be important, not as a public health problem, but because the investigation of these experimental models of nature has provided information to increase our understanding of control of glycolysis and interrelationships of the Rapoport-Luebering shunt, mechanism of hemolysis, erythrocyte ageing, role of isozymes in various organs, and genetic control of enzyme structure/function. The application of ever improving techniques of recombinant DNA should yield a bonanza of new information to improve our comprehension of the pathogenesis and heterogeneity of these disorders as well as provide increased knowledge of regulation of these enzymes. It should be an exciting era.
 
Article
Replacement therapy for hemophilia A has evolved from the early use of whole blood, citrated plasma, and cryoprecipitate, to purified factor VIII (FVIII) concentrates, first derived from plasma, then produced by recombinant DNA technology. Recombinant FVIII (rFVIII) concentrates have provided improved safety for patients with hemophilia A since they significantly reduce the risk of transmission of blood-borne infections. Nevertheless, human- or animal-derived plasma proteins are still included at some step in preparation of all previously licensed rFVIII, thereby introducing the potential for transmission of human or animal pathogens. Anti-hemophilic factor (recombinant), plasma/albumin-free method (rAHF-PFM), a novel advanced category rFVIII produced without the addition of human or animal plasma proteins, has been developed with the goal of providing the greatest possible margin of safety to hemophilia patients. This report, based on a symposium of the XIXth International Society on Thrombosis and Haemostasis Congress, provides an overview of the rAHF-PFM development program as well as current findings from the global clinical evaluation of rAHF-PFM in pediatric and adult previously treated patients.
 
Article
Great advances have been made in the management of Rh erythroblastosis fetalis in the past two decades. Perinatal mortality has been reduced from 16.4% to 3.2%. However, perinatal mortality can only be reduced to zero if Rh erythroblastosis can be eradicated by prevention of Rh isoimmunization. Although prevention of Rh immunization by Rh immune globulin prophylaxis is now a reality, it does not appear that Rh immunization will be completely prevented with a single postdelivery injection. Antenatal treatment plus screening by the Kleihauer technique for massive transplacental hemorrhage may be necessary before complete suppression can be achieved. Low protein Rh immune globulin, and ultimately column-produced, very low protein, highly purified Rh immune globulin for intravenous use may prove to be the safest, most economical, and effective material for Rh prevention and total eradication of Rh erythroblastosis fetalis.
 
Article
Between 1981 and 1986, we treated 179 newly diagnosed patients with advanced-stage malignant lymphoma or related conditions with methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, bleomycin (MACOP-B). Experience with 12 different histologic subtypes indicates that MACOP-B is acceptably tolerated and effective for diffuse large cleaved cell, diffuse large noncleaved cell, diffuse mixed large and small cleaved cell, immunoblastic, and discordant lymphomas but not for angioimmunoblastic lymphadenopathy or for diffuse small cleaved cell, follicular large cell, follicular mixed large and small cleaved cell, acquired immune deficiency syndrome (AIDS)-related, unclassifiable, or small noncleaved cell lymphomas. Pooled long-term results for the 126 patients with variants of diffuse large cell lymphoma (cleaved, noncleaved, immunoblastic, and mixed) show an actuarial relapse-free survival of 67% for the 86% of patients who had a complete response and an overall survival for all patients of 65% at 78 months of follow-up. Analysis of toxicity reveals a substantially higher risk of lethal toxicity in patients over 59 years of age. MACOP-B should only be used for patients with one of the diagnoses for which it is effective; meticulous care should be taken to prevent severe toxicity in older patients.
 
Article
In this review I have outlined the molecular basis and prenatal diagnosis of alpha-thalassemia and then concentrated on the state of our knowledge of the molecular basis of beta-thalassemia and its prenatal diagnosis. I discussed the improved but more complicated genetic counselling now available as a result of our increased knowledge of the effects of various defects in the beta-globin gene. Our knowledge of the heterogeneous molecular basis of the thalassemia syndromes has become very impressive and it is hoped that effective therapy will soon follow. For the present, however, prevention of the birth of affected children is the most effective means of reducing the suffering associated with the thalassemia syndromes, and prevention of this type is succeeding in many parts of the world, including North America.
 
Article
The myelodysplastic syndromes (MDS) continue to pose conceptual and practical conundrums because of their heterogeneity and therapeutic challenges. They are not restricted to the presence of clonal cells that are prone to excessive proliferation and premature apoptosis. In MDS the bone marrow microenvironment also is abnormal and exhibits an excess of proinflammatory cytokines, especially tumor necrosis factor (TNF), neoangiogenesis, and poorly defined immune defects. Thalidomide, a drug with anti-TNF, antiangiogenic, and immunomodulatory activities, and other agents with anti-TNF effects, such as pentoxifylline, etanercept, and infliximab, have produced hematologic improvement in 20% to 40% of patients. These agents may provide effective therapy for a subset of lower-risk MDS patients, even if the drugs target the bone marrow microenvironment predominantly. However, in higher-risk MDS patients, especially those with more than 10% blasts, it is important to eliminate abnormal cell clones; drugs used for this purpose have included arsenic trioxide, topotecan, the farnesyl transferase inhibitor tipifarnib, and demethylating agents, such as 5-azacytidine and decitabine. To increase the therapeutic index, a combination strategy may be preferable for higher-risk MDS patients, in whom the seed (clone) and the soil (bone marrow microenvironment) must be targeted simultaneously. The challenge is to recognize the subset that is likely to respond to a given drug so that patients can be preselected for therapy.
 
Article
In the last two decades, progress in the diagnosis of von Willebrand disease (VWD) came from the rapidly developing field of molecular techniques that allowed the first phenotype-genotype correlations. In particular, structural and functional defects of von Willebrand factor (VWF) that underlie VWD type 2 and their molecular basis not only helped to understand the pathophysiology of VWD but also the complex post-translation processing of VWF and the multiple VWF functions. In contrast to the dramatic development of molecular techniques, improvement of methods for phenotypic description, a prerequisite for phenotype-genotype comparisons, has been neglected. The gold standard to differentiate VWD type 2 from type 1 and between diverse type 2 subtypes is the electrophoretic analysis of VWF multimers, a demanding technique that itself is not easily standardized but of crucial relevance for correct classification. This article summarizes the current knowledge on phenotype-genotype correlations as well as up-to-date phenotypic and genotypic methods in the diagnosis of VWD.
 
Article
The eighth edition (AT8) of the American College of Chest Physicians (ACCP) Antithrombotic Therapy and Prevention of Thrombosis Guideline, published in June 2008, was a comprehensive presentation of primary studies and detailed discussions of rationale for recommendations. This resulted in an approximately 900-page Chest Supplement publication. Updating the guidelines in a succinct fashion posed a formidable challenge for the ninth edition (AT9), published in February 2012. The strategy adopted for AT9 was to publish an Executive Summary of the recommendations in a 50-page document in the Chest supplement highlighting the changes, with online publication of the full version. Major innovative changes include a recognition of the value of estimating the risk reductions in symptomatic, as opposed to asymptomatic (venographically), detected venous thrombosis, using nonconflicted methodologists as topic editors, new insights into evidence, and increasing emphasis on what is known about patients' values and preferences that have served to improve this edition of the guidelines. This review provides a summary of the updates of the guidelines for anticoagulation therapy and prevention of thrombosis. The AT9 recommendations are presented with, if included, the AT8 recommendations in parenthesis for comparison purposes.
 
Article
This volume of Seminars focuses on graft-versus-host disease (GVHD), a highly morbid toxicity of allogeneic hematopoietic stem cell transplant (HSCT). The toxicity of GVHD limits theaccessibilityofHSCTtopatientswhoseunderlyingdiseaseis either incurable with standard chemotherapy or who have already failed standard approaches. An improved understanding of the pathophysiology of GVHD should lead to better preventive, diagnostic, and therapeutic strategies, thus making allogeneic HSCT more widely available. Hence the timeliness of this volume. Acute GVHD occurs in up to 40% of patients undergoing related donor HSCT 1,2 and in up to 70% of patients undergoing unrelated donor HSCT. 3 The clinical manifestations of GVHD, reviewed by Deeg and Antin, usually become manifest within the first month following stem cell infusion. Less than 40% of patients with acute GVHD experience complete responses to high-dose corticosteroids, 4,5 leading to significant morbidity and mortality from chronic corticosteroid therapy. The severity of acute GVHD continues to be measured by changes in three primary target organs (skin, liver and intestines), 4,6 but a strong case can be made to also considerthelungatargetofGVHD,asreviewedinthechapterby Yanik and Cooke. The initial models for GVHD pathophysiology were based, logically enough, on a paradigm of solid organ rejection mediated by cytotoxic T lymphocytes. This useful model has led to effective strategies for GVHD prevention, as well as establishing a role for donor leukocytes to treat relapse after transplant,asreviewedinthechapterbyPorterandLevine.Recent
 
Article
The DiGeorge anomaly (DGA), originally considered a clinical paradigm for isolated thymus deficiency, has now been redefined as a member of a group of disorders that share in common a chromosome deletion, which results in monosomy 22q11 (CATCH-22 or DiGeorge/velocardiofacial [VCFS] syndrome). In addition to the thymus defect, conotruncal heart anomalies, dysmorphism, hypoparathyroidism, and cleft palate are prominent features. Despite the emphasis on thymus involvement in DGA, a clinically significant thymus defect is found only in a small percentage of these patients. The basic embryological fault in these disorders is an inadequate development of the facial neural crest tissues, resulting in defective organogenesis of pharyngeal pouch derivatives. Although first described by an endocrinologist, this experiment of nature has become a major subject of investigation for geneticists and immunologists. Elucidation of the etiology and attempts to effectively treat the diverse clinical problems continue to challenge and stimulate many disciplines of medicine both in the laboratory and at the bedside.
 
Article
Immunocytic dyscrasias may be manifested by MIDD often presenting with renal manifestations. The diagnosis is established when deposits are shown by immunopathologic methods to contain a single light-chain isotype in patients who have a monoclonal Ig in the serum or urine, altered kappa:lambda ratio in bone marrow, and/or abnormal biosynthesis of Igs in bone marrow cell cultures. The morphologic expressions of deposits are varied: fibrillar in AL, granular and punctate in LCDD, granular or crystalline in LHCDD, and crystalline in type I cryoglobulinemia.
 
Article
Arsenic compounds, Including arsenic trioxide (As2O3) and arsenic sulfide (As4S4), have recently been shown to be effective in the treatment of acute promyelocytic leukemia (APL). In vitro, As2O3 exerts a dose-dependent dual effect: it triggers apoptosis at relatively high concentrations (0.5 to 2.0 micromol/L) and induces partial differentiation at low concentrations (0.1 to 0.5 micromol/L). The apoptosis-inducing effect is associated with the collapse of mitochondrial transmembrane potentials in a thiol-dependent manner, whereas the retinoic acid signaling is required for APL cell differentiation. As2O3 over a wide range of concentrations (0.1 to 2.0 micromol/L) Induces degradation of PML-RARalpha as well as the wild-type PML and enhances the acetylation of histone, a process important for the transcriptional activation of genes. In vivo, As2O3 induces a high complete remission (CR) rate in patients with both primary and relapsed APL (around 85% to 90%). Side effects, such as skin reaction, gastrointestinal symptoms, electrocardiographic (EKG) changes, neuropathy, and liver dysfunction, are mild to moderate in relapsed patients, and severe hepatic lesions have been found in some primary cases. After CR obtained in relapsed patients, chemotherapy in combination with As2O3 as postremission therapy has yielded better survival than treatment with As2O3 alone. This is in line with the observation that remission induction with As2O3 is not sufficient in most cases to obtain a molecular remission as Judged by reverse-transcriptase polymerase chain reaction for PML-RARalpha fusion transcripts. The in vivo effect of As2O3 seems to be related to the expression of APL-specific PML-RARalpha oncoprotein, and a synergistic effect between As2O3 and ATRA has been shown in the APL mouse model. Besides As2O3, other arsenic compounds such as As4S4 also show a therapeutic effect in APL. Because the toxic effects of arsenic treatment in primary APL need to be investigated further, we propose use of ATRA as a first-line drug for remission induction in primary APL, whereas As2O3 can be incorporated into multidrug postremission therapy or used as rescue for relapsed APL patients.
 
Article
Inhibition of antibody-coated platelet destruction in patients with immune thrombocytopenic purpura (ITP) is a well-known mechanism of treatment effect. A number of interventions that would ameliorate the thrombocytopenic effect of ITP patient plasma when infused into normal recipients were demonstrated in 1965. Subsequently, the antibody-coated chromium-labeled red blood cell clearance study was developed to allow direct in vivo assessment of Fc receptor (FcR) blockade. This was first demonstrated for corticosteroids but more extensive investigation began with the study of intravenous infusions of gammaglobulin (IVIg). The unequivocal demonstration of FcR blockade following IVIg Initiated novel approaches. One involved the infusion of a monoclonal anti-FcRIII ligand-blocking antibody into patients with refractory ITP. The efficacy of this treatment demonstrated that FcR blockade was not an epiphenomenon but rather an important mechanism of the increase in the platelet count in patients with ITP. Confirmation of its importance was obtained from the infusion of intravenous (IV) anti-D and the use of the isolated Fc piece of IgG. Recent studies have begun to explore the possibility of a monoclonal anti-FcRI and monoclonal anti-Ds. In summary, FcR blockade is an important mechanism of treatment effect in patients with ITP. Cytokine release as a consequence of this interaction and other immunomodulatory effects have only begun to be studied.
 
Article
Comparative genomic hybridization (CGH) has contributed significantly to the current knowledge of genomic alterations in hematologic malignancies. Characteristic patterns of genomic imbalances not only have confirmed recent classification schemes in non-Hodgkin's lymphoma, but they provide a basis for the successful identification of genes with previously unrecognized pathogenic roles in the development of different lymphomas. Based on its technical limitations, there is little reason to apply CGH to chromosomes of metaphase cells in routine diagnostic settings. However, the new approach of CGH to DNA microarrays, a procedure termed matrix-CGH, overcomes most of the limitations and opens new approaches for diagnostics and identification of genetically defined leukemia and lymphoma subgroups. Current efforts to develop leukemia specific matrix-CGH DNA chips, which are designed to meet the clinical needs, are presented and discussed.
 
Article
Iron metabolism and superoxide metabolism are clearly interactive, especially under pathological conditions. Each can exacerbate the toxicity of the other. Iron overload may amplify the damaging effects of superoxide overproduction in a very broad spectrum of inflammatory or ischemia-related conditions. Furthermore, chronic oxidative stress may modulate iron uptake and storage, leading to a self-sustained and ever-increasing spiral of cytotoxic and mutagenic events.
 
Article
Hereditary elliptocytosis (HE) is a common disorder of erythrocyte shape, occurring especially in individuals of African and Mediterranean ancestry, presumably because elliptocytes confer some resistance to malaria. The principle lesion in HE is mechanical weakness or fragility of the erythrocyte membrane skeleton due to defects in alpha-spectrin, beta-spectrin, or protein 4.1. Numerous mutations have been described in the genes encoding these proteins, including point mutations, gene deletions and insertions, and mRNA processing defects. Several mutations have been identified in a number of individuals on the same genetic background, suggesting a "founder effect." The majority of HE patients are asymptomatic, but some may experience hemolytic anemia, splenomegaly, and intermittent jaundice.
 
Article
The band 4.2 protein offers several challenges for those studying the erythrocyte membrane in particular and biological membranes in general. The first challenge will be to define the function of the protein in the erythrocyte membrane. The discovery of the function of band 4.2 in the erythrocyte will no doubt provide insight into why band 4.2 deficient cells are lost from the circulation at an accelerated rate. Many hemolytic anemias related to deficiencies or defects in membrane proteins result from instabilities of the membrane skeleton or defective skeletal-membrane attachment, and it is possible that these factors may also play a role in some anemias related to band 4.2 deficiency. This would imply either that band 4.2 plays some direct role in membrane skeletal integrity or function, or that an alteration in some other membrane component, band 3 for example, is responsible for both band 4.2 deficiency and skeletal dysfunction. According to current thinking regarding the etiology of abnormal erythrocyte morphology, band 4.2 deficiency resulting in elliptocytosis could be related to alterations in 'horizontal' skeletal stability, eg, in junctional complex formation or dimer-dimer association, whereas deficiencies associated with spherocytic erythrocytes may be associated with 'vertical' instabilities related to skeletal-membrane attachment. Whether such skeletal aberrations could be a result of band 4.2 deficiency or whether the aberration and deficiency are both caused by some other factor or defect remains to be seen. Although many cases of band 4.2 deficiency have been characterized as HS or hereditary elliptocytosis other cases have been reported to have normal or nearly normal morphology with no apparent membrane loss or cellular fragmentation (see section 1). Thus some cases of anemia associated with band 4.2 deficiency may be due to erythrocyte alterations unrelated to cellular fragmentation or shape change. One possible explanation for this class of band 4.2 deficient anemias may be related to effects of band 4.2 on other membrane proteins such as band 3. It may be, for example, that band 4.2 affects the self-association of band 3 and that this somehow induces enhanced band 3 antigenicity leading to premature erythrocyte destruction via antigenic recognition. This hypothesis would be consistent with the enhanced mobility of band 3 seen in band 4.2 deficient erythrocytes shown in Table 2. Thus, as with many other erythrocyte disorders, anemias associated with band 4.2 deficiency may have multiple causes depending on whether the deficiency is the primary defect or the result of an alteration in some other membrane component. The N-myristylation of band 4.2 is another topic requiring further investigation. The ability to purify band 4.2 in milligram quantities, and the possibility of expressing non-myristylated mutants of band 4.2 in vitro offer the possibility of discovering what role this cotranslational modification plays in the function of the protein. These studies are of considerable interest because the role of myristic acid in the function of myristylated proteins, many of which are involved in cellular signaling pathways, is poorly understood. Finally, the discovery that a mutation in the band 4.2 gene is likely responsible for the pallid mutation in mice offers the possibility to uncover the function of band 4.2 analogues in nonerythroid cells. It may be that nonerythroid band 4.2 proteins associate with the membranes of secretory vesicles in a variety of cell types, and are involved either in the regulation of secretory vesicle membrane stability or in the fusion of secretory vesicles with plasma membranes. Further studies in this area will likely result in the characterization of a previously undescribed family of proteins which is central to the process of secretion in many types of cells.
 
Article
The authors have employed the multiparameter approach on several large case series. In these reported case series the classification of cases is based entirely on the morphologic features and the designated cytologic type compared with the results of the multiparameter studies. These studies confirm the T and B cell types of the Lukes-Collins classification and the rarity of histiocytic lymphoma. The present report includes the results on 425 cases of non-Hodgkin lymphomas and related leukemias as well as review the immunologic background of our functional approach. It also considers briefly the new clinical-immunologic cytologic entities that are emerging from the redefinition of the malignant lymphomas.
 
Article
Purine analogues have been shown to be active in a variety of B- and T-cell malignancies. Among them, pentostatin is also a tight binding inhibitor of adenosine deaminase (ADA), a key enzyme of purine metabolism. ADA is present in all human tissues, with the highest levels in the lymphoid system. Early clinical trials with pentostatin used high doses for acute lymphoblastic leukemias, which were characterized by high levels of ADA. Through the efforts of a few investigators, low-dose regimens that are active and well tolerated for indolent lymphoid malignancies have been developed. Myelosuppressive adverse effects have been shown to be minimal using these schedules. Lymphoplasmacytic lymphoma (LL) is an indolent chronic B-cell lymphoproliferative disorder moderately responsive to alkylating agents. All of the purine analogues have shown activity in LL. However, the advantage of pentostatin over the other agents is the relatively specific toxicity to lymphoid cells and the paucity of myelosuppression as a single agent. No direct comparisons of the agents have been investigated, although pentostatin may be considered to be preferred since it has not been associated with toxicity to myeloid progenitors in colony assays. This is of significance for patients who might benefit from high-dose chemotherapy with autologous stem cell transplantation.
 
Platelets and the immune continuum. On this schematic drawing, acknowledged experiments are assembled such as to place the platelet participation in immune reactions into perspective. Looking at the figure more closely, one becomes aware of platelet involvement in inflammation as well as in innate and adaptive immune surveillance. Reproduced from Semple et al.45 Figure lent by Dr. Semple. doi:10.1038/nri2956. Permission granted by NRI/NPG through the CCC.
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The Intercontinental Cooperative immune thrombocytopenia (ITP) Study Group (ICIS) held its 4th Expert Meeting in September 2012 in Montreux, Switzerland. The program reunited researchers and clinicians from all over the globe and was organized with lectures and seminars for real-time exchange of latest information. Platelets target victims of autoimmune disease on their own, participating under physiological conditions in the immune network; these small cells are more immunologically savvy than previously thought. Currently, researchers focus their attention on regulatory T and regulatory B cells, ie, cells that might have a decisive impact on how ITP spontaneously resolves or evolves into chronic disease. Diagnostic criteria and prognosis are increasingly benefiting from molecular biological tests, and therapy has evolved with the availability of biosimilar agents and recombinant hormones or blockers of their receptors.
 
Top-cited authors
David Cella
  • Northwestern University
Marc Gertz
  • Florida State University
Paul D Berk
  • Columbia University
Harry J Iland
  • Royal Prince Alfred Hospital
John A Hansen
  • Fred Hutchinson Cancer Research Center