losartan-potassium and Myeloproliferative-Disorders

Thromboembolic complications are the second leading cause of death in cancer patients. In contrast to the large body of literature on venous thromboembolism (VTE), relatively few reports have focused on the pathogenesis, incidence, management and outcomes of arterial thromboembolic events in patients with malignancy. The purpose of this article is to review the current literature on the etiology, mechanisms, and prognosis of arterial thromboembolic events in cancer patients and outline appropriate screening and management guidelines that may help lower the rates of morbidity and mortality related to these events.

Topics: Algorithms; Amyloidosis; Antineoplastic Agents; Antiphospholipid Syndrome; Erythropoietin; Female; Humans; Ischemia; Male; Myeloproliferative Disorders; Neoplasms; Neurofibromatosis 1; Peripheral Arterial Disease; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Prognosis; Radiation Injuries; Recombinant Proteins; Risk Factors; Thromboembolism; Thrombophilia; Transfusion Reaction

Topics: Adrenal Cortex Hormones; Angiogenesis Inhibitors; Antineoplastic Agents; Antineoplastic Agents, Hormonal; Breast Neoplasms; Clinical Trials as Topic; Erythropoietin; Female; Humans; Models, Biological; Multiple Myeloma; Myeloproliferative Disorders; Neoplasms; Recombinant Proteins; Risk; Thrombophilia; Thrombosis; Venous Thromboembolism

Formation of endogenous erythroid colonies (EECs) or endogenous megakaryocytic colonies (EMCs) is a hallmark of myeloproliferative disorders (MPDs). The diagnostic value of EEC for polycythemia vera (PV) using standardized media has been demonstrated, and has led clinicians to consider EEC as a major diagnostic criterion in the WHO classification. The interest of EEC currently needs to be considered taking into account recent data about V617F JAK2 mutation in MPD. In particular, EECs and EMCs should be helpful for the diagnostic and the vascular risk evaluation of essential thrombocythemia (ET) and for mutation negative patients. A low serum erythropoietin (EPO) level is a consistent finding in PV. Recent studies have shown that commercial serum EPO assays provided a reliable, accurate, and low-cost criterion for the diagnosis of a significant proportion of PV. It suggests that diagnostic algorithms integrating serum EPO level could be elaborated. The diagnostic value of EPO assay for thrombocytosis has not been proved, but some data suggest a predictive value of low EPO levels for thrombosis in ET.

Topics: Colony-Forming Units Assay; Erythropoietin; Humans; Myeloproliferative Disorders; Polycythemia Vera; Thrombocythemia, Essential

In early 2005, several groups of investigators studying myeloid malignancies described a novel somatic point mutation (V617F) in the conserved autoinhibitory pseudokinase domain of the Janus kinase 2 (JAK2) protein, which plays an important role in normal hematopoietic growth factor signaling. The V617F mutation is present in blood and marrow from a large proportion of patients with classic BCR/ABL-negative chronic myeloproliferative disorders and of a few patients with other clonal hematological diseases such as myelodysplastic syndrome, atypical myeloproliferative disorders, and acute myeloid leukemia. The JAK2 V617F mutation causes constitutive activation of the kinase, with deregulated intracellular signaling that mimics continuous hematopoietic growth factor stimulation. Within 7 months of the first electronic publication describing this new mutation, clinical molecular diagnostic laboratories in the United States and Europe began offering JAK2 mutation testing on a fee-for-service basis. Here, I review the various techniques used by research groups and clinical laboratories to detect the genetic mutation underlying JAK2 V617F, including fluorescent dye chemistry sequencing, allele-specific polymerase chain reaction (PCR), real-time PCR, DNA-melting curve analysis, pyrosequencing, and others. I also discuss diagnostic sensitivity, performance, and other practical concerns relevant to the clinical laboratorian in addition to the potential diagnostic utility of JAK2 mutation tests.

Topics: Base Sequence; Biomarkers; Erythropoietin; Humans; Janus Kinase 2; Models, Biological; Molecular Diagnostic Techniques; Molecular Sequence Data; Mutation; Myelodysplastic Syndromes; Myeloproliferative Disorders; Polycythemia; Polymerase Chain Reaction; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Thrombocytosis

Essential thrombocythemia, polycythemia vera, and myelofibrosis with myeloid metaplasia constitute the "classic" bcr/abl-negative myeloproliferative disorders (MPDs). Each of these MPDs represents a stem cell-derived clonal myeloproliferation with the respective features of thrombocytosis, erythrocytosis, and bone marrow fibrosis. Unlike with cases of chronic myeloid leukemia, in which the bcr/abl mutation is invariably detected, current diagnosis of essential thrombocythemia, polycythemia vera, and myelofibrosis with myeloid metaplasia is based on a consensus-driven set of clinical and laboratory criteria that have undergone substantial modification in recent times. The recent discovery of a recurrent activating Janus tyrosine kinase (JAK2) mutation (JAK2VG17F) in all 3 classic MPDs offers another opportunity for refining current diagnoses and disease classifications. In this article, we outline contemporary diagnostic algorithms for each of these disorders and provide an evidence-based approach to management.

Topics: Erythropoietin; Genes, abl; Humans; Myeloproliferative Disorders; Prognosis

Topics: Anemia; Apoptosis; Clone Cells; Disease Progression; Erythropoiesis; Erythropoietin; Female; Growth Substances; Hematologic Tests; Hematopoietic Stem Cells; Humans; Iron; Leukemia, Myeloid; Male; Myeloproliferative Disorders; Phlebotomy; Phosphorus Radioisotopes; Polycythemia Vera; Pregnancy; Pregnancy Complications, Hematologic; Receptors, Erythropoietin; Receptors, Growth Factor; Thrombocytosis; Thrombosis

Polycythemia rubra vera (PV) is one of four diseases collectively called the myeloproliferative disorders (MPDs). Each disorder leads to an increased production of one or several hematopoietic cell lineages. MPDs arise from acquired mutations in a pluripotent hematopoietic stem cell. However, the molecular mechanisms leading to the development of these diseases are poorly understood. This review will summarize and evaluate recent advances in our understanding of one particular MPD, PV.

Topics: bcl-X Protein; Erythropoietin; GPI-Linked Proteins; Growth Substances; Humans; Isoantigens; Membrane Glycoproteins; Myeloproliferative Disorders; Neoplasm Proteins; Phosphoprotein Phosphatases; Polycythemia Vera; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Receptors, Cell Surface; Receptors, Cytokine; Receptors, Erythropoietin; Receptors, Thrombopoietin; Signal Transduction; Stem Cells

Topics: Anemia, Aplastic; Animals; Bone Marrow Cells; Cell Differentiation; Cell Division; Cells, Cultured; Clone Cells; Colony-Forming Units Assay; Erythrocytes; Erythropoiesis; Erythropoietin; Hematologic Diseases; Hemoglobins; Humans; Immunosuppression Therapy; Mice; Myeloproliferative Disorders; Syndrome; T-Lymphocytes; Time Factors

Topics: Arteries; Basophils; Blood Platelets; Blood Volume Determination; Bone Marrow; Erythrocytes; Erythropoiesis; Erythropoietin; Granulocytes; Hematocrit; Hemoglobins; Hepatomegaly; Humans; Megakaryocytes; Myeloproliferative Disorders; Osteosclerosis; Oxygen Consumption; Polycythemia; Polycythemia Vera; Primary Myelofibrosis; Splenomegaly

We found that in regenerative erythropoiesis, the erythroid progenitor landscape is reshaped, and a previously undescribed progenitor population with colony-forming unit-erythroid (CFU-E) activity (stress CFU-E [sCFU-E]) is expanded markedly to restore the erythron. sCFU-E cells are targets of erythropoietin (Epo), and sCFU-E expansion requires signaling from the Epo receptor (EpoR) cytoplasmic tyrosines. Molecularly, Epo promotes sCFU-E expansion via JAK2- and STAT5-dependent expression of IRS2, thus engaging the progrowth signaling from the IGF1 receptor (IGF1R). Inhibition of IGF1R and IRS2 signaling impairs sCFU-E cell growth, whereas exogenous IRS2 expression rescues cell growth in sCFU-E expressing truncated EpoR-lacking cytoplasmic tyrosines. This sCFU-E pathway is the major pathway involved in erythrocytosis driven by the oncogenic JAK2 mutant JAK2(V617F) in myeloproliferative neoplasm. Inability to expand sCFU-E cells by truncated EpoR protects against JAK2(V617F)-driven erythrocytosis. In samples from patients with myeloproliferative neoplasm, the number of sCFU-E-like cells increases, and inhibition of IGR1R and IRS2 signaling blocks Epo-hypersensitive erythroid cell colony formation. In summary, we identified a new stress-specific erythroid progenitor cell population that links regenerative erythropoiesis to pathogenic erythrocytosis.

Topics: Erythroid Precursor Cells; Erythropoiesis; Erythropoietin; Humans; Myeloproliferative Disorders; Neoplasms; Polycythemia; Receptor, IGF Type 1; Receptors, Erythropoietin

Topics: Diagnostic Screening Programs; Erythropoietin; Female; Humans; Janus Kinase 2; Male; Middle Aged; Mutation; Myeloproliferative Disorders; Polycythemia Vera; Pruritus; Retrospective Studies; Water

The JAK2V617F mutation that results in a hyper-activation of the JAK2 kinase in the erythropoietin pathway is a molecular marker for myeloproliferative neoplasms. Using allele-specific Real-Time PCR, we detected the mutation in the blood of 17.3% (17/98) of normal donors; the mutant allele burden was, however, very low (<0.01% compared to >1% in polycythemia vera). It was much higher in differentiated blood cells in the peripheral blood than in undifferentiated CD34

Topics: Animals; Blood Donors; Cell Differentiation; Erythroid Precursor Cells; Erythropoietin; Humans; Janus Kinase 2; Mice; Mutation; Mutation Rate; Myeloproliferative Disorders

Topics: Adult; Biomarkers, Tumor; Bone Marrow; Calreticulin; Erythropoietin; Female; Fusion Proteins, bcr-abl; Hematocrit; Hemoglobins; Humans; Janus Kinase 2; Male; Middle Aged; Mutation; Myeloproliferative Disorders; Polycythemia Vera; Receptors, Thrombopoietin; Thrombocythemia, Essential; World Health Organization

Overexpression of transcription factors runt-related transcription factor 1 (RUNX1) and nuclear factor, erythroid-derived 2 (NF-E2) was reported in granulocytes of patients with polycythemia vera and other myeloproliferative neoplasms (MPNs). Further, a transgenic mouse overexpressing the NF-E2 transgene was reported to be a model of MPN. We hypothesized that increased transcripts of RUNX1 and NF-E2 might characterize other polycythemic states with primary polycythemic features, that is, those with exaggerated erythropoiesis due to augmented erythropoietin (EPO) sensitivity. We tested the expression of RUNX1 and NF-E2 in polycythemic patients of diverse phenotypes and molecular causes. We report that RUNX1 and NF-E2 overexpression is not specific for MPN; these transcripts were also significantly elevated in polycythemias with augmented hypoxia-inducible factor activity whose erythroid progenitors were hypersensitive to EPO. RUNX1 and NF-E2 overexpression was not detected in patients with EPO receptor (EPOR) gain-of-function, suggesting distinct mechanisms by which erythroid progenitors in polycythemias with defects of hypoxia sensing and EPOR mutations exert their EPO hypersensitivity.

Topics: Animals; Cell Hypoxia; Core Binding Factor Alpha 2 Subunit; Erythropoietin; Gene Expression Regulation; Granulocytes; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Leukocytes, Mononuclear; Mice; Mice, Transgenic; Mutation; Myeloproliferative Disorders; NF-E2 Transcription Factor, p45 Subunit; Polycythemia; Signal Transduction

Clinical significance of the JAK2V617F mutation in patients with a myeloproliferative neoplasm has been the target of intensive research in recent years. However, there is considerably uncertainty about prognosis in JAK2V617F positive individuals without overt signs of myeloproliferative disease. In this study, we tested the hypothesis that increased JAK2V617F somatic mutation burden is associated with myeloproliferative neoplasm progression rate in the general population. Among 49,488 individuals from the Copenhagen General Population Study, 63 (0.1%) tested positive for the JAK2V617F mutation in the time period 2003-2008. Of these, 48 were available for re-examination in 2012. Level of JAK2V617F mutation burden was associated with myeloproliferative neoplasm progression rate, consistent with a biological continuum of increasing JAK2V617F mutation burden across increasing severity of myeloproliferative neoplasm from no disease (n=8 at re-examination) through essential thrombocythemia (n=20) and polycythemia vera (n=13) to primary myelofibrosis (n=7). Among those diagnosed with a myeloproliferative neoplasm only at re-examination in 2012, in the preceding years JAK2V617F mutation burden increased by 0.55% per year, erythrocyte volume fraction increased by 1.19% per year, and erythrocyte mean corpuscular volume increased by 1.25% per year, while there was no change in platelet count or erythropoietin levels. Furthermore, we established a JAK2V617F mutation burden cut-off point of 2% indicative of disease versus no disease; however, individuals with a mutation burden below 2% may suffer from a latent form of myeloproliferative disease revealed by a slightly larger spleen and/or slightly higher lactic acid dehydrogenase concentration compared to controls. Of all 63 JAK2V617F positive individuals, 48 were eventually diagnosed with a myeloproliferative neoplasm.

Topics: Aged; Aged, 80 and over; Blood Platelets; Denmark; Disease Progression; Erythrocyte Indices; Erythropoietin; Female; Genetic Testing; Hematologic Neoplasms; Humans; Janus Kinase 2; Male; Middle Aged; Mutation; Myeloproliferative Disorders; Platelet Count; Prospective Studies; Registries; Severity of Illness Index

JAK2(V617F) is the predominant mutation in myeloproliferative neoplasms (MPN). Modeling MPN in a human context might be helpful for the screening of molecules targeting JAK2 and its intracellular signaling. We describe here the derivation of induced pluripotent stem (iPS) cell lines from 2 polycythemia vera patients carrying a heterozygous and a homozygous mutated JAK2(V617F), respectively. In the patient with homozygous JAK2(V617F), additional ASXL1 mutation and chromosome 20 allowed partial delineation of the clonal architecture and assignation of the cellular origin of the derived iPS cell lines. The marked difference in the response to erythropoietin (EPO) between homozygous and heterozygous cell lines correlated with the constitutive activation level of signaling pathways. Strikingly, heterozygous iPS cells showed thrombopoietin (TPO)-independent formation of megakaryocytic colonies, but not EPO-independent erythroid colony formation. JAK2, PI3K and HSP90 inhibitors were able to block spontaneous and EPO-induced growth of erythroid colonies from GPA(+)CD41(+) cells derived from iPS cells. Altogether, this study brings the proof of concept that iPS can be used for studying MPN pathogenesis, clonal architecture, and drug efficacy.

Topics: Cells, Cultured; Erythropoietin; Humans; Induced Pluripotent Stem Cells; Janus Kinase 2; Myeloproliferative Disorders; Phosphatidylinositol 3-Kinases; Repressor Proteins; Signal Transduction; Thrombopoietin

Overexpression of high mobility group AT-hook 2 (HMGA2) is found in a number of benign and malignant tumors, including the clonal PIGA(-) cells in 2 cases of paroxysmal nocturnal hemoglobinuria (PNH) and some myeloproliferative neoplasms (MPNs), and recently in hematopoietic cell clones resulting from gene therapy procedures. In nearly all these cases overexpression is because of deletions or translocations that remove the 3' untranslated region (UTR) which contains binding sites for the regulatory micro RNA let-7. We were therefore interested in the effect of HMGA2 overexpression in hematopoietic tissues in transgenic mice (ΔHmga2 mice) carrying a 3'UTR-truncated Hmga2 cDNA. ΔHmga2 mice expressed increased levels of HMGA2 protein in various tissues including hematopoietic cells and showed proliferative hematopoiesis with increased numbers in all lineages of peripheral blood cells, hypercellular bone marrow (BM), splenomegaly with extramedullary erythropoiesis and erythropoietin-independent erythroid colony formation. ΔHmga2-derived BM cells had a growth advantage over wild-type cells in competitive repopulation and serial transplantation experiments. Thus overexpression of HMGA2 leads to proliferative hematopoiesis with clonal expansion at the stem cell and progenitor levels and may account for the clonal expansion in PNH and MPNs and in gene therapy patients after vector insertion disrupts the HMGA2 locus.

Topics: 3' Untranslated Regions; Animals; Biomarkers, Tumor; Blotting, Western; Bone Marrow; Clone Cells; DNA, Complementary; Erythropoietin; Flow Cytometry; Gene Expression Profiling; Hematopoiesis; Hematopoietic Stem Cells; HMGA2 Protein; Humans; Immunoenzyme Techniques; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myeloproliferative Disorders; Oligonucleotide Array Sequence Analysis; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger

Myeloproliferative neoplasms (MPNs) are associated with recurrent activating mutations of signaling proteins such as Janus kinase 2 (JAK2). However, the actual downstream signaling events and how these alter myeloid homeostasis are poorly understood. We developed an assay to measure basal levels of phosphorylated signaling intermediates by flow cytometry during myeloid differentiation in MPN patients. Our study provides the first systematic demonstration of specific signaling events and their comparison with disease phenotype and JAK2 mutation status. We demonstrate increased basal signaling in MPN patients, which occurs in both early and later stages of myeloid differentiation. In addition, the pattern of signaling is not correlated with JAK2 mutation status and signaling intensity is poorly correlated with mutant JAK2 allele burden. In contrast, signaling differences are detected between different MPN disease phenotypes. Finally, we demonstrate that signaling can be inhibited by a JAK2-selective small molecule, but that this inhibition is not JAK2 V617F specific, because MPN patients with mutant JAK2, wild-type JAK2, and control patients were inhibited to a similar degree. Our data suggest that, in addition to JAK2 mutations, other factors contribute significantly to the MPN phenotype, results that are relevant to both the pathogenesis and therapy of MPN.

Topics: Aged; Blotting, Western; Cell Line, Tumor; Erythropoietin; Female; Flow Cytometry; Genotype; Hematopoietic Stem Cells; Humans; Intracellular Space; Janus Kinase 2; Male; Middle Aged; Mutation; Myeloproliferative Disorders; Phenotype; Phosphoproteins; Phosphorylation; Polycythemia Vera; Primary Myelofibrosis; Pyrimidines; Signal Transduction; Sulfonamides; Thrombocythemia, Essential

We report a Jak2V617F knockin mouse myeloproliferative neoplasm (MPN) model resembling human polycythemia vera (PV). The MPN is serially transplantable and we demonstrate that the hematopoietic stem cell (HSC) compartment has the unique capacity for disease initiation but does not have a significant selective competitive advantage over wild-type HSCs. In contrast, myeloid progenitor populations are expanded and skewed toward the erythroid lineage, but cannot transplant the disease. Treatment with a JAK2 kinase inhibitor ameliorated the MPN phenotype, but did not eliminate the disease-initiating population. These findings provide insights into the consequences of JAK2 activation on HSC differentiation and function and have the potential to inform therapeutic approaches to JAK2V617F-positive MPN.

Topics: Amino Acid Substitution; Animals; Antigens, CD; Bone Marrow; Bone Marrow Cells; Bone Marrow Transplantation; Cell Count; Cell Differentiation; Disease Models, Animal; Erythroid Precursor Cells; Erythropoietin; Gene Expression; Gene Expression Profiling; Hematocrit; Hematopoietic Stem Cell Transplantation; Hematopoietic Stem Cells; Heterozygote; Humans; Janus Kinase 2; Megakaryocyte Progenitor Cells; Megakaryocyte-Erythroid Progenitor Cells; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myeloid Progenitor Cells; Myeloproliferative Disorders; Polycythemia Vera; Protein Kinase Inhibitors; Pyrrolidines; Spleen; Sulfonamides; Survival Analysis

Elevated haemoglobin and erythrocytosis are frequent causes for investigation.. A 50-year-old woman with elevated haemoglobin and erythrocytosis was referred to our hospital for investigation.. She had elevated serum erythropoietin and iron deficiency. Mutational status of the JAK2 gene was negative with respect to polycythemia vera, and no secondary reasons for polycythemia - including tumours - were revealed. A bone marrow biopsy and bone marrow smear showed a moderately increased number of lambda- positive monoclonal plasma cells, and small amounts of lambda light chains were detected in the urine. Serum electrophoreses showed no gammopathy. The reason for her elevated haemoglobin could be an erythropoietin-producing tumour or an idiopathic erythrocytosis based on a mutation in exon 12 of the JAK2 gene. Investigation of her plasma cells revealed a 10-fold increase in erythropoietin mRNA expression, indicating the reason for her elevated serum erythropoietin and haemoglobin values.

Topics: Bone Marrow Examination; Diagnosis, Differential; Erythropoietin; Female; Gene Expression; Hemoglobins; Humans; Iron Deficiencies; Middle Aged; Multiple Myeloma; Myeloproliferative Disorders; Polycythemia; Polycythemia Vera; RNA, Messenger

Topics: Diagnosis, Differential; Erythropoietin; Hemoglobins; Humans; Myeloproliferative Disorders; Plasma Cells; Polycythemia Vera; Risk Factors; RNA, Messenger

The V617F activating point mutation in Jak2 is associated with a proportion of myeloproliferative disorders. In normal hematopoietic cells, Jak2 signals only when associated with a growth factor receptor, such as the erythropoietin receptor (EpoR). We sought to identify the molecular requirements for activation of Jak2V617F by introducing a point mutation in the FERM domain (Y114A), required for receptor binding. Whereas BaF3.EpoR cells are readily transformed by Jak2V617F to Epo independence, we found that the addition of the FERM domain mutation blocked transformation and the induction of reactive oxygen species. Further, while cells expressing Jak2V617F had constitutive activation of STAT5, cells expressing Jak2V617F/Y114A did not, suggesting that signaling is defective at a very proximal level. In addition, expression of the Myc and Pim proto-oncogenes by Jak2V617F was found to be FERM domain dependent. An inducible constitutively active STAT5 mutant expressed in BaF3 cells was sufficient to induce Myc and Pim. Finally, the FERM domain in Jak2V617F was also required for abnormal hematopoiesis in transduced primary murine fetal liver cells. Overall, our results suggest that constitutive activation of Jak2 requires an intact FERM domain for a transforming phenotype, and is necessary for activation of the major target of Jak2, STAT5.

Topics: Animals; Cell Line, Tumor; Cell Transformation, Neoplastic; Enzyme Activation; Erythropoietin; Gene Expression Regulation, Neoplastic; Hematopoiesis, Extramedullary; Humans; Janus Kinase 2; Liver; Mice; Mutation, Missense; Myeloproliferative Disorders; Protein Serine-Threonine Kinases; Protein Structure, Tertiary; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-myc; Proto-Oncogene Proteins c-pim-1; Reactive Oxygen Species; Receptors, Erythropoietin; Signal Transduction; STAT5 Transcription Factor; Transduction, Genetic

The JAK2(V617F) mutation was found in most patients with myeloproliferative disorders (MPDs), including polycythemia vera, essential thrombocythemia, and primary myelofibrosis. We have generated transgenic mice expressing the mutated enzyme in the hematopoietic system driven by a vav gene promoter. The mice are viable and fertile. One line of the transgenic mice, which expressed a lower level of JAK2(V617F), showed moderate elevations of blood cell counts, whereas another line with a higher level of JAK2(V617F) expression displayed marked increases in blood counts and developed phenotypes that closely resembled human essential thrombocythemia and polycythemia vera. The latter line of mice also developed primary myelofibrosis-like symptoms as they aged. The transgenic mice showed erythroid, megakaryocytic, and granulocytic hyperplasia in the bone marrow and spleen, displayed splenomegaly, and had reduced levels of plasma erythropoietin and thrombopoietin. They possessed an increased number of hematopoietic progenitor cells in peripheral blood, spleen, and bone marrow, and these cells formed autonomous colonies in the absence of growth factors and cytokines. The data show that JAK2(V617F) can cause MPDs in mice. Our study thus provides a mouse model to study the pathologic role of JAK2(V617F) and to develop treatment for MPDs.

Topics: Animals; Erythropoietin; Hematopoietic Stem Cells; Hyperplasia; Janus Kinase 2; Mice; Mice, Transgenic; Mutation, Missense; Myeloproliferative Disorders; Phenotype; Thrombopoietin; Transgenes

The somatic JAK2 valine-to-phenylalanine (V617F) mutation has been detected in up to 90% of patients with polycythemia and in a sizeable proportion of patients with other myeloproliferative disorders such as essential thrombocythemia and idiopathic myelofibrosis. Suppressor of cytokine signaling 3 (SOCS3) is known to be a strong negative regulator of erythropoietin (EPO) signaling through interaction with both the EPO receptor (EPOR) and JAK2. We report here that JAK2 V617F cannot be regulated and that its activation is actually potentiated in the presence of SOCS3. Instead of acting as a suppressor, SOCS3 enhanced the proliferation of cells expressing both JAK2 V617F and EPOR. Additionally, although SOCS1 and SOCS2 are degraded in the presence of JAK2 V617F, turnover of SOCS3 is inhibited by the JAK2 mutant kinase and this correlated with marked tyrosine phosphorylation of SOCS3 protein. We also observed constitutive tyrosine phosphorylation of SOCS3 in peripheral blood mononuclear cells (PBMCs) derived from patients homozygous for the JAK2 V617F mutant. These findings suggest that the JAK2 V617F has overcome normal SOCS regulation by hyperphosphorylating SOCS3, rendering it unable to inhibit the mutant kinase. Thus, JAK2 V617F may even exploit SOCS3 to potentiate its myeloproliferative capacity.

Topics: Animals; Erythropoietin; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Janus Kinase 2; Leukocytes, Mononuclear; Mice; Mutation; Myeloproliferative Disorders; Phenylalanine; Signal Transduction; Suppressor of Cytokine Signaling 3 Protein; Suppressor of Cytokine Signaling Proteins; Valine

Topics: Adolescent; Adult; Bone Marrow Cells; Erythroid Cells; Erythropoietin; Female; Humans; Male; Middle Aged; Myeloproliferative Disorders; Tumor Stem Cell Assay

The JAK2(V617F) mutation is present in almost all patients with polycythemia vera (PV), large proportions of patients with essential thrombocythemia and idiopathic myelofibrosis, and less frequently in atypical myeloproliferative disorders (MPD). We show that transplantation of JAK2(V617F)-transduced bone marrow into BALB/c mice induces MPD reminiscent of human PV, characterized by erythrocytosis, granulocytosis, extramedullary hematopoiesis, and bone marrow fibrosis, but not thrombocytosis. Fluorescence-activated cell sorting of bone marrow and spleen showed proportional expansion of common myeloid progenitors, granulocyte-monocyte and megakaryocyte-erythrocyte progenitors. Megakaryocyte and late erythroid progenitors were dramatically increased, with only modest expansion of early erythroid progenitors. Erythropoietin (Epo) receptor expression was reduced on early, but normal on late erythroblasts. Serum levels of Epo and granulocyte colony-stimulating factor, but not granulocyte macrophage colony-stimulating factor, were reduced, whereas tumor necrosis factor-alpha was increased, possibly exerting a negative effect on JAK2(V617F)-negative hematopoiesis. These data suggest that erythrocytosis and granulocytosis in JAK2(V617F) mice are the net result of a complex interplay between cell intrinsic and extrinsic factors. There were no thromboembolic events and no animals succumbed to their disease, implicating additional factors in the manifestation of human disease. The disease was not transplantable and prolonged observation showed normalization of blood counts in most JAK2(V617F) mice, suggesting that the mutation may not confer self-renewal capacity.

Topics: Animals; Bone Marrow; Bone Marrow Cells; Bone Marrow Transplantation; Cell Line; Clone Cells; Erythropoietin; Fibrosis; Granulocyte Colony-Stimulating Factor; Hematopoiesis, Extramedullary; Hematopoietic Stem Cells; Humans; Janus Kinase 2; Mice; Mice, Inbred BALB C; Mutation, Missense; Myeloproliferative Disorders; Polycythemia; Polycythemia Vera; Receptors, Erythropoietin; Spleen; Time Factors; Transfection; Tumor Necrosis Factor-alpha

Myeloproliferative disorders (MPD) are reported in 25-65% of patients with splanchnic vein thrombosis (SVT). Diagnostic criteria for MPD have not been fully established in this context. Using clusters of abnormal megakaryocytes in bone marrow (BM) biopsy as a reference standard for Philadelphia negative MPD, we assessed the relevance of other criteria currently recommended for the diagnosis of MPD in SVT (128 consecutive SVT patients). First, usual criteria were compared with BM results: endogenous erythroid colony formation (EEC) was strongly correlated with BM results; splenomegaly, blood cell count, total red cell volume, erythropoietin level and cytogenetic were much less accurate. Then, patients were assigned to three groups according to the combination of BM and EEC findings (group I: both present; group II: both absent; group III: other patients); clinical presentation and outcome were compared in each group. At a mean follow-up of 6.09 +/- 6.6 years, progression to a severe form of MPD occurred in 7 of 31 group I patients (23%), in 1 of 34 group III patients (3%) and 0 of 63 group II patients. The combination of marked splenomegaly and platelet count >200 x 10(9)/l was restricted to groups I and III. In conclusion, in patients with SVT, BM findings and EEC allowed the diagnosis of MPD at risk of aggravation. Marked splenomegaly in association with platelet counts >200 x 10(9)/l constitute a simple index with high specificity but low sensitivity.

Topics: Bone Marrow Cells; Cytogenetic Analysis; Erythrocyte Volume; Erythroid Precursor Cells; Erythropoietin; Follow-Up Studies; Humans; Megakaryocytes; Myeloproliferative Disorders; Phenotype; Platelet Count; Sensitivity and Specificity; Splanchnic Circulation; Splenomegaly; Statistics, Nonparametric; Venous Thrombosis

Myeloproliferative disorders (MPD) represent a subcategory of hematological malignancies and are characterized by a stem cell-derived clonal proliferation of myeloid cells including erythrocytes, platelets, and leucocytes. Traditionally, the term 'MPD' included chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), and myelofibrosis with myeloid metaplasia (MMM). At present, these four disorders are referred to as 'classic' MPD and are distinguished from a spectrum of other MPD-like clinicopathologic entities that are operationally classified as 'atypical' MPD. The oncogenic mutations(s) in classic MPD are unknown except for CML, which is associated with an activating mutation (Bcr/Abl) of the gene encoding for the Abl cytoplasmic protein kinase (PTK). In the last 3 months, a somatic point mutation of JAK2 (JAK2(V617F)), the gene encoding for another cytoplasmic PTK was reported in the majority of patients with PV and approximately half of those with either ET or MMM. The same mutation was also found in a small number of patients with either atypical MPD or the myelodysplastic syndrome but not in normal controls, germline tissue including T lymphocytes, and patients with secondary erythrocytosis. In vitro, JAK2(V617F) was associated with constitutive phosphorylation of JAK2 and its downstream effectors as well as induction of erythropoietin hypersensitivity in cell lines. In vivo, murine bone marrow transduced with a retrovirus containing JAK2(V617F) induced erythrocytosis in the transplanted mice. Taken together, these observations suggest that JAK2(V617F) is an acquired myeloid lineage-specific mutation that engenders a pathogenetic relevance for the PV phenotype in MPD.

Topics: Alleles; Animals; Bone Marrow Cells; Cell Lineage; Cell Proliferation; Cytoplasm; DNA; DNA Mutational Analysis; Erythrocytes; Erythropoietin; Homozygote; Humans; Janus Kinase 2; Mice; Mutation; Myelodysplastic Syndromes; Myeloproliferative Disorders; Phenotype; Phosphorylation; Phosphotransferases; Point Mutation; Polycythemia; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Sequence Analysis, DNA; T-Lymphocytes; Tyrosine; Up-Regulation

Myeloproliferative disorders (MPDs) are heterogeneous diseases that occur at the level of a multipotent hematopoietic stem cell. They are characterized by increased blood cell production related to cytokine hypersensitivity and virtually normal cell maturation. The molecular pathogenesis of the MPDs has been poorly understood, except for chronic myeloid leukemia (CML), where the Bcr-Abl fusion protein exhibits constitutive kinase activity. Since some rare MPDs are also related to a dysregulated kinase activity, a similar mechanism was thought to be likely responsible for the more frequent MPDs. We investigated the mechanisms of endogenous erythroid colony formation (EEC) by polycythemia vera (PV) erythroid progenitor cells and found that EEC formation was abolished by a pharmacological inhibitor of JAK2 as well as an siRNA against JAK2. JAK2 sequencing revealed a unique mutation in the JH2 domain leading to a V617F substitution in more than 80% of the PV samples. This mutation in the pseudokinase autoinhibitory domain results in constitutive kinase activity and induces cytokine hypersensitivity or independence of factor-dependent cell lines. Retroviral transduction of the mutant JAK2 into murine HSC leads to the development of an MPD with polycythemia. The same mutation was found in about 50% of patients with idiopathic myelofibrosis (IMF) and 30% of patients with essential thrombocythemia (ET). Using different approaches, four other teams have obtained similar results. The identification of the JAK2 mutation represents a major advance in our understanding of the molecular pathogenesis of MPDs that will likely permit a new classification of these diseases and the development of novel therapeutic approaches.

Topics: Amino Acid Substitution; Cell Division; Cytokines; Erythrocytes; Erythropoietin; Humans; Janus Kinase 2; Leukemia, Myelogenous, Chronic, BCR-ABL Positive; Mutation; Myeloproliferative Disorders; Polycythemia Vera; Receptors, Erythropoietin; Signal Transduction

Decreased expression of c-MPL protein in platelets, increased expression of polycythemia rubra vera 1 (PRV-1) and nuclear factor I-B (NFIB) mRNA in granulocytes, and loss of heterozygosity on chromosome 9p (9pLOH) were described as molecular markers for myeloproliferative disorders (MPDs). To assess whether these markers are clustered in subgroups of MPDs or represent independent phenotypic variations, we simultaneously determined their status in a cohort of MPD patients. Growth of erythropoietin-independent colonies (EECs) was measured for comparison. We observed concordance between EECs and PRV-1 in MPD patients across all diagnostic subclasses, but our results indicate that EECs remain the most reliable auxiliary test for polycythemia vera (PV). In contrast, c-MPL, NFIB, and 9pLOH constitute independent variations. Interestingly, decreased c-MPL and elevated PRV-1 also were observed in patients with hereditary thrombocythemia (HT) who carry a mutation in the thrombopoietin (TPO) gene. Thus, altered c-MPL and PRV-1 expression also can arise through a molecular mechanism different from sporadic MPD.

Topics: Chronic Disease; Cohort Studies; Erythropoietin; GPI-Linked Proteins; Humans; Isoantigens; Loss of Heterozygosity; Membrane Glycoproteins; Microsatellite Repeats; Myeloproliferative Disorders; Neoplasm Proteins; NFI Transcription Factors; Proteins; Proto-Oncogene Proteins; Receptors, Cell Surface; Receptors, Cytokine; Receptors, Thrombopoietin

Topics: Diagnosis, Differential; Erythropoietin; France; Hemoglobinopathies; Hemoglobins, Abnormal; Humans; Male; Middle Aged; Myeloproliferative Disorders; Oxyhemoglobins; Polycythemia

We reported a rare case of pancytopenia caused by allopurinol. A 61-year-old man was first admitted in May 1993, because of thrombocytosis. He had suffered from chronic glomerulonephritis. He was administered allopurinol for hyperuricemia from March 1993. On first admission the laboratory findings revealed leukocytosis (10,100/microliter) and thrombocytosis (971 x 10(3)/microliter) in the peripheral blood. Myelofibrosis was strongly suspected due to increased number of MgK and reticular fiber in the bone marrow. Two months later, he readmitted due to pancytopenia (WBC 1,300/microliter, Hb 6.2g/dl, Plt 10 x 10(3)/microliter). His bone marrow showed markedly hypocellular. Because we suspected that pancytopenia was induced by allopurinol, we discontinued allopurinol and administered oxymetholone, G-CSF, and EPO, WBC, RBC, and platelet count had been recovered about one and half months later. In vitro co-culture indicated that CFU-G, E, and Meg in the bone marrow cells after recovery from pancytopenia were markedly suppressed in the presence of patient's serum and oxipurinol. Pancytopenia due to allopurinol was reported to be rare, and some authors showed that it will sometimes be fatal. Because pancytopenia of this case had been recovered in a relatively short time with cytokine therapy, it was thought to be effective for pancytopenia due to drug like this case.

Topics: Allopurinol; Antimetabolites; Drug Therapy, Combination; Erythropoietin; Granulocyte Colony-Stimulating Factor; Humans; Male; Middle Aged; Myeloproliferative Disorders; Oxymetholone; Pancytopenia; Recombinant Proteins

The present study revises the criteria of the Polycythemia Vera Group (PVSG) for the diagnoses of essential thrombocythemia (ET) and polycythemia vera (PV) in view of accumulating data on in vitro cultures of hematopoietic progenitors and by adding histopathology from bone marrow biopsies. The majority of ET patients show spontaneous megakaryocyte or erythroid growth or both, but in about 35% the growth pattern is normal. So far none of the patients with reactive thrombocytosis have shown either spontaneous megakaryocyte or erythroid colony growth. Virtually all PV patients show spontaneous or endogenous erythroid colony (EEC) formation, whereas patients with secondary erythrocytosis and healthy controls do not show any erythroid colony growth in the absence of erythropoietin (EPO). Some rare patients with a disorder other than a myeloproliferative disease (MPD) may show spontaneous growth of erythroid colonies caused by a mutation in the EPO receptor. Megakaryocytes in bone marrow smears and biopsy material from ET and PV patients are typically increased in number and size. Enlarged megakaryocytes with mature cytoplasm and multilobulated nuclei and the tendency of these megakaryocytes to cluster in a normal or slightly increased cellular bone marrow represent the diagnostic hallmark of ET. Increase and clustering of enlarged, mature, and pleiomorphic megakaryocytes in a moderate to marked hypercellular bone marrow with hyperplasia of dilated sinuses is the diagnostic feature of untreated PV. In reactive thrombocytosis and secondary erythrocytosis the size and morphology of megakaryocytes remain normal and there is no tendency of the megakaryocytes to cluster. Both spontaneous EEC and histopathology of bone marrow biopsies appear to offer specific clues to the diagnosis of overt and latent ET or PV and have the potential to differentiate ET from reactive thrombocytosis and PV from secondary erythrocytosis. Moreover, bone marrow histopathology has the diagnostic power to distinguish and to stage the various MPDs without regard to clinical and laboratory data.

Topics: Biopsy; Bone Marrow; Bone Marrow Examination; Erythroid Precursor Cells; Erythropoiesis; Erythropoietin; Female; Humans; Male; Megakaryocytes; Myeloproliferative Disorders; Polycythemia Vera; Primary Myelofibrosis; Thrombocythemia, Essential

The human erythropoietin receptor (EpoR) gene has been cloned and characterized. Very few EpoR genetic abnormalities have been reported so far. Polycythemia vera (PV) is characterized by low/normal serum erythropoietin (Epo) levels with proposed Epo hypersensitivity. Myelodysplastic syndromes (MDS) are characterized by refractory anemia with variable serum Epo levels. Several reports have suggested EpoR abnormalities in both types of stem cell disorders. We analyzed DNA obtained from peripheral blood mononuclear cells of seven healthy controls, 20 patients with myeloproliferative disorders (MPD, 11 patients with PV, five agnogenic myeloid metaplasia with myelofibrosis, four essential thrombocytosis) and eight patients with refractory anemia with ringed sideroblasts (RARS), an MDS variant. The DNA was digested with four restriction enzymes (BamHI, Bgl II, Sacl and HindIII), followed by Southern blot, using a 32P radiolabeled probe, containing 1.5 kb of the human EpoR cDNA. All 20 MPD patients and seven out of the eight MDS patients demonstrated a restriction pattern which was identical to the seven normal controls, as well as to the erythroid cell line K562, and also consistent with the expected restriction map, for all four enzymes tested. One RARS patient had a normal pattern with three enzymes but a different one with HindIII. The HindIII 12 kb large band was replaced by a faint 12 kb band and a new (about 9 kb) band appeared. The EpoR restriction map and the normal pattern obtained with the other three enzymes suggest that this patient has a 3 kb upstream deletion in one allelic EpoR gene. The same molecular pattern was detected in the patient's sister, who suffers from anemia with mild bone marrow (BM) dyserythropoiesis and plasmacytosis. Northern blot analysis showed that the patient's BM RNA carried normal EpoR message. This familial pattern may represent polymorphism. However, the patient's very high serum Epo level, her resistance to treatment with recombinant Epo, and the abnormally low growth rate of in vitro erythroid cultures, suggesting poor response to Epo in this MDS patient as well as the hematological abnormalities in her sister, support the speculation that the different EpoR gene might serve as a genetic predisposing marker and potentially could be involved (probably via post-transcriptional mechanisms and by an interaction with other factors or cytokines) in the pathogenesis. Our data suggest that the EpoR is intact in MPD and in most

Topics: Aged; Blotting, Northern; DNA; DNA, Neoplasm; Erythroid Precursor Cells; Erythropoietin; Family Health; Female; Humans; Leukemia, Erythroblastic, Acute; Male; Myelodysplastic Syndromes; Myeloproliferative Disorders; Prognosis; Receptors, Erythropoietin; RNA; Tumor Cells, Cultured

We have studied the effects of interferons gamma (IFN-gamma) and alpha (IFN-alpha), and tumour-necrosis factor-alpha (TNF) on circulating 14-day erythroid progenitor cell (BFU-E) growth in vitro from patients with non-leukaemic myeloproliferative disorders (MPD) compared with normal controls. IFN-gamma (1000 U/ml) inhibited BFU-E growth in all controls studied (mean growth +/- SE = 61% +/- 6%, n = 10). In 7 of 11 MPD studied there was no inhibition, and in some cases clear enhancement of BFU-E growth by IFN-gamma. When cultured in the presence of recombinant erythropoietin (rEpo) 1 U/ml, both IFN-alpha and TNF (at 100 and 1000 U/ml) produced a similar degree of inhibition of BFU-E growth in MPD and controls. The inhibition by 100 U/ml IFN-alpha was abrogated, partially in controls but completely in MPD, by increasing the dose of rEpo to 5 U/ml. Similarly, the increase in rEpo dose enhanced BFU-E growth in cultures with 100 U/ml TNF, but had little effect on cultures containing 1000 U/ml of either IFN-alpha or TNF. The aberrant in vitro response to IFN-gamma demonstrated in some of these patients may be of relevance to the pathophysiology of MPD. These results fail to demonstrate a differential in vitro effect for IFN-alpha on MPD BFU-E growth compared with controls and suggest that the in vitro suppression of haemopoiesis by IFN-alpha when used in MPD treatment is non-specific.

Topics: Cells, Cultured; Erythroid Precursor Cells; Erythropoiesis; Erythropoietin; Humans; In Vitro Techniques; Interferon-alpha; Interferon-gamma; Myeloproliferative Disorders; Recombinant Proteins; Tumor Necrosis Factor-alpha

Cultures of hematopoietic precursor cells can be helpful in differentiating between primary polycythemia (polycythaemia vera, PV) and reactive secondary polycythemia: in PV erythroid precursors form hemoglobinized colonies in the absence of added erythropoietin (epo) (= endogenous erythroid colonies), whereas in normals and in patients with secondary polycythemia, formation of erythroid colonies is dependent on added epo. We have performed cultures of peripheral blood precursors from 132 patients with elevated hemoglobin in the presence/absence of added epo. In 48/132 patients we assumed that PV was the cause of polycythemia. In 80/132 patients no endogenous colonies appeared and the polycythemia was judged secondary. 23 PV patients were examined repeatedly. In 18 of them the first diagnosis was confirmed by subsequent cultures; in 5 cases endogenous colonies, which had been present in the first cultures, were no longer detectable. A questionnaire on the subsequent clinical course was sent to 108 treating physicians. 77 questionnaires were answered correctly and returned. In 86% of these patients, our culture diagnosis of PV was either confirmed or another myeloproliferative disorder had been found as a cause of endogenous colonies. In 14% our diagnosis of PV had been false positive. On the other hand, our diagnosis of secondary polycythemia was confirmed in 85% of the patients; its most frequent cause was cigarette smoking and chronic bronchitis and only rarely was it associated with heart or kidney disease. 5/77 patients had persistently elevated Hb without an evident cause, and in 3/77 the Hb normalized spontaneously.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Colony-Forming Units Assay; Diagnosis, Differential; Erythroid Precursor Cells; Erythropoietin; False Positive Reactions; Hematopoietic Stem Cells; Humans; Myeloproliferative Disorders; Polycythemia; Polycythemia Vera

Serum erythropoietin (Epo) titers in patients with various hematological malignancies and related diseases were determined by radioimmunoassay. Serum Epo titer was inversely correlated with hemoglobin concentration in iron deficiency anemia, aplastic anemia, myelodysplastic syndromes (MDS), acute leukemia, malignant lymphoma, multiple myeloma and myelofibrosis, but there was no correlation between serum Epo titer and hemoglobin concentration in chronic myelogenous leukemia or polycythemias. Serum Epo titers in aplastic anemia were much higher than those in iron deficiency anemia. Serum Epo titers in MDS, malignant lymphoma and multiple myeloma differed considerably among patients. Serum Epo titers in untreated polycythemia vera were significantly lower than in treated polycythemia vera or secondary polycythemia.

Topics: Anemia; Erythropoietin; Hemoglobins; Humans; Myeloproliferative Disorders; Polycythemia Vera

Topics: Colony-Forming Units Assay; Erythroid Precursor Cells; Erythropoietin; Hematopoietic Stem Cells; Humans; Myelodysplastic Syndromes; Myeloproliferative Disorders; Thrombocytosis

Topics: Aged; Aged, 80 and over; Anemia; Erythropoietin; Female; Humans; Male; Myeloproliferative Disorders; Recombinant Proteins

Topics: Aged; Erythropoietin; Female; Humans; Male; Middle Aged; Myeloproliferative Disorders; Splenomegaly

Topics: Erythropoietin; Humans; Myeloproliferative Disorders; Radioimmunoassay

Megakaryocyte colony formation, as identified by conventional techniques, was observed in precursor cell cultures from peripheral blood in 8 of 20 consecutive patients with diagnosis of myeloproliferative disease (4/11 patients with polycythemia vera, 3/5 with essential thrombocythemia, 1/2 with primary osteomyelofibrosis and 2 with a myeloproliferative syndrome not further assessable), but not in 50 healthy controls (p less than 0.0001). 7 cultures showed spontaneous erythroid colonies, but were negative for megakaryocyte colonies. Megakaryocyte colony formation was independent of added erythropoietin, plasma or human leukocyte-conditioned medium, but was dependent on the presence of accessory cells. The cells in megakaryocyte colonies had the characteristic morphology of megakaryocytes and stained positively with the IIIa/IIb monoclonal anti-platelet antibody. Thus, megakaryocyte colony formation by precursor cells from peripheral blood in the absence of exogenous stimulating factors seems to be a phenomenon specific for myeloproliferative disease. Differential diagnosis of thrombocythemia may be facilitated by demonstration of endogenous megakaryocyte colony formation, which does not occur in secondary disease.

Topics: Cell Nucleus; Cells, Cultured; Colony-Forming Units Assay; Culture Media; Cytoplasm; Diagnosis, Differential; Erythropoietin; Fluorescent Antibody Technique; Hematopoietic Stem Cells; Humans; Leukocytes; Megakaryocytes; Myeloproliferative Disorders; Polycythemia Vera; Primary Myelofibrosis; Thrombocythemia, Essential

X-chromosome DNA probes for the phosphoglycerate kinase (PGK) and hypoxanthine phosphoribosyl transferase (HPRT) genes were used to study clonality in haemopoietic cells from 63 women with myeloproliferative disease, idiopathic erythrocytosis, secondary erythrocytosis or normal red cell volumes. A total of 25 women (39%) were heterozygous for one of the polymorphisms associated with these genes. Clonality was demonstrated in five out of six patients with polycythaemia vera (PV) and in three other patients with myeloproliferative disease. In all cases of PV, including the patient in whom clonality was not demonstrated, cultures of peripheral blood showed growth of endogenous erythroid colonies.

Topics: Clone Cells; DNA Probes; Erythropoietin; Female; Heterozygote; Humans; Myeloproliferative Disorders; Polycythemia; Stem Cells; X Chromosome

Topics: Adult; Aged; Aged, 80 and over; Colony-Forming Units Assay; Colony-Stimulating Factors; Erythropoietin; Female; Growth; Hematopoietic Stem Cells; Humans; Male; Middle Aged; Myelodysplastic Syndromes; Myeloproliferative Disorders

A chronic myeloproliferative disorder associated with monosomy 7 is described in a 3 1/2-year-old boy. His presenting features closely resembled those of juvenile chronic myeloid leukaemia (JCML). Cytogenetic study of bone marrow cells showed that all of the metaphases examined had chromosome 7 deletions. He developed an erythroblastic phase, characterized by anaemia, marked erythroid hyperplasia of bone marrow and the appearance of nucleated red blood cells in the peripheral blood. During the erythroblastic phase, blood transfusion resulted in a suppression of erythropoiesis as evidenced in both the peripheral blood and bone marrow. The in vitro culture studies showed that the erythroid precursor was dependent upon erythropoietin (Ep) for differentiation and proliferation during the erythroblastic phase. However, the Ep dose-response curve showed that a peak of erythroid colony formation occurred at a lower concentration than in the healthy controls. These findings suggest that although the erythroid precursor remains under the control of Ep, it has an increased sensitivity to Ep during the erythroblastic phase of monosomy 7.

Topics: Blast Crisis; Blood Transfusion; Child, Preschool; Chromosome Deletion; Chromosomes, Human, Pair 7; Erythropoiesis; Erythropoietin; Humans; Karyotyping; Male; Monosomy; Myeloproliferative Disorders

We assessed the prevalence of overt and latent primary myeloproliferative disorders in hepatic vein thrombosis. Cultures of bone marrow or peripheral blood mononuclear cells were done in 20 patients with Budd-Chiari syndrome. Erythroid colony formation in the absence of erythropoietin, which is a reliable indicator for a primary myeloproliferative disorder, was seen in 16 patients in whom Budd-Chiari syndrome was due to hepatic vein thrombosis, including 13 women aged 18 to 45 years. Among these 16 patients, the conventional criteria for the diagnosis of a primary myeloproliferative disorder were met in only 2. Primary myeloproliferative disorder, often without peripheral blood changes, is a major cause of hepatic vein thrombosis in young women.

Topics: Adolescent; Adult; Budd-Chiari Syndrome; Colony-Forming Units Assay; Contraceptives, Oral; Erythrocyte Volume; Erythropoiesis; Erythropoietin; Female; Hematopoietic Stem Cells; Humans; Male; Middle Aged; Myeloproliferative Disorders; Polycythemia Vera; Prospective Studies

Serum erythropoietin (ESF) levels and the numbers of marrow and blood erythroid progenitors (CFU-Es) of patients with chronic myeloproliferative disorders (CMPD) were studied simultaneously. The numbers of marrow and blood CFU-Es per 1 x 10(5) cells were normal or greatly elevated. There was an inverse correlation between the hemoglobin concentration and the serum ESF level in patients with chronic myelogenous leukemia when the hemoglobin concentration ranged from 9.0 to 13.0 g/100 ml. The serum ESF level was closely related to the hemoglobin concentration in CMPD and it was suggested that the negative feedback mechanism might operate in anemic patients with CMPD.

Topics: Adult; Animals; Bone Marrow Cells; Cell Count; Chronic Disease; Erythropoietin; Female; Hematopoietic Stem Cells; Hemoglobins; Humans; Leukemia, Myeloid; Male; Mice; Middle Aged; Myeloproliferative Disorders; Polycythemia Vera; Primary Myelofibrosis; Thrombocytosis

Growth patterns of marrow and blood erythroid progenitors were studied in 18 cases of pure erythrocytosis using different doses of erythropoietin. 8 cases demonstrated 'spontaneous' growth of CFU-E and blood BFU-E as observed in myeloproliferative disorders, but without an excess of circulating CFU-GM. 3 of these patients also had other symptoms of a pan-myelopathy. All these cases showed good sensitivity to 32P myelo-suppression. 10 cases demonstrated growth patterns of erythroid progenitors similar to those observed in normal subjects, except for an excess of blood BFU-E, which suggests an abnormality of homeostatic regulation. In 5 of these cases, myelo-suppression was not effective. It is suggested that a stem cell study could differentiate patients with pure erythrocytosis due to 'autonomous' abnormal stem cell growth from cases due to abnormal regulation factors, and that such a discrimination might be useful for the choice of therapy.

Topics: Cells, Cultured; Erythroblasts; Erythrocytes; Erythropoietin; Female; Hematopoietic Stem Cells; Humans; Male; Middle Aged; Myeloproliferative Disorders; Polycythemia

Serum of patients suffering from a chronic myeloproliferative disorder (polycythaemia, era, osteomyelofibrosis, chronic myeloid leukaemia) and serum of lethally irradiated rats injected before application of a single doses of erythropoietin did not enhance the effect of erythropoietin -- measured with the iron incorporation rate of polycythemic mice. The rationale for these experiments is to try to find a "myeloproliferative factor", which augments the number of stem cells as described in sera of patients with polycythaemia vera, osteomyelofibrosis, and lethally irradiated mice.

Topics: Adult; Aged; Drug Synergism; Erythropoietin; Humans; Leukemia, Myeloid; Middle Aged; Myeloproliferative Disorders; Polycythemia Vera; Primary Myelofibrosis

Topics: Animals; Erythropoietin; Female; Hematopoietic Stem Cells; Humans; Mice; Mycotoxins; Myeloproliferative Disorders

Topics: Adolescent; Adult; Aged; Blood Platelets; Bone Marrow Diseases; Diagnosis, Differential; Erythrocyte Count; Erythropoietin; Female; Hematocrit; Hemoglobinometry; Humans; Leukemia, Myeloid; Leukocyte Count; Male; Middle Aged; Myeloproliferative Disorders; Polycythemia Vera; Primary Myelofibrosis; Retrospective Studies

Topics: Adolescent; Adult; Aged; Anemia, Aplastic; Anemia, Sideroblastic; Bone Marrow Diseases; Erythropoietin; Female; Humans; Iron; Iron Isotopes; Kidney Failure, Chronic; Male; Middle Aged; Myeloproliferative Disorders; Oxymetholone