thromboplastin and Polycythemia-Vera

Thrombotic complications in patients with hematologic malignancies are as frequent as in those with solid tumors and significantly affect morbidity and mortality. In acute leukemia, thrombosis and bleeding manifestations may occur concomitantly as a part of the same thrombo-hemorrhagic syndrome. In patients with Philadelphia chromosome-negative chronic myeloproliferative disorders (i.e., essential thrombocythemia [ET] and polycythemia vera [PV]), a thrombosis rate as high as 40% has been recorded. A hypercoagulable state is present in virtually all of these patients, even without clinical manifestations. In this review, we focus on the pathogenic mechanisms underlying the hypercoagulable state of these two hematologic malignancies. Although the pathogenesis of hypercoagulability is complex, a central role is played by the fundamental molecular changes of both the leukemic cells and of the progeny arising from the hematopoietic progenitor cells that have undergone clonal rearrangement. These cells overexpress procoagulant factors, as well as adhesion molecules and cytokines capable of inducing procoagulant changes in the vascular wall and stimulating increased cellular interactions. Recent molecular studies in experimental models of human tumors have demonstrated for the first time that oncogene- and repressor gene-mediated neoplastic transformation induces activation of blood coagulation. Similarly, in cells from patients with acute promyelocytic leukemia, the T15-17 translocation induces hyperexpression of tissue factor (TF) and renders the patient hypercoagulable. Furthermore, in blood cells from patients with PV or ET, the presence of the JAK2V617F mutation translates into activation of hemostasis, with increased expression of platelet-associated TF microparticles and the formation of increased platelet/neutrophil aggregates. Understanding the pathophysiology of hypercoagulability is critical to the design of appropriate measures for intervention in these hematologic disorders to prevent thromboembolic complications.

Topics: Hematologic Neoplasms; Hemostasis; Humans; Leukemia, Promyelocytic, Acute; Myeloproliferative Disorders; Neovascularization, Pathologic; Polycythemia Vera; Thrombocythemia, Essential; Thrombophilia; Thromboplastin; Up-Regulation

Topics: Aminocaproates; Animals; Anticoagulants; Antifibrinolytic Agents; Antigens; Aprotinin; Blood Cell Count; Blood Coagulation; Blood Coagulation Disorders; Blood Platelets; Chromatography; Chromatography, Gel; Dogs; Epidermolysis Bullosa; Fibrinogen; Fibrinolysis; Hematocrit; Immunoelectrophoresis; Injections, Intravenous; Iodine Isotopes; Liver Cirrhosis; Peptides; Polycythemia Vera; Potassium Iodide; Thrombin; Thromboplastin; Thrombosis

Topics: Blood Transfusion; Enzyme Inhibitors; Female; Fibrin; Fibrinogen; Fibrinolysin; Fibrinolysis; Hemostatics; Humans; Leukemia; Liver Cirrhosis; Male; Pathology; Physiology; Polycythemia Vera; Pregnancy; Pregnancy Complications; Pregnancy Complications, Hematologic; Prostatectomy; Prostatic Neoplasms; Prothrombin; Thrombin; Thromboplastin

Topics: Blood Coagulation; Humans; Janus Kinase 2; Neutrophils; Point Mutation; Polycythemia Vera; Thrombocytosis; Thromboplastin; Up-Regulation

The clinical courses of polycythemia vera (PV) and essential thrombocythemia (ET) are characterized by thrombohemorrhagic diathesis. Several groups have suggested an association between JAK2V617F mutation and thrombosis. We hypothesized a relationship between JAK2V617F allele burden, cellular activation parameters, and thrombosis. We evaluated a group of PV and ET patients using flow cytometry: platelet CD62P, CD63, and dense granules, platelet-leukocyte aggregates (PLA), leukocyte CD11b and monocyte tissue factor (TF) expression. All patients had increased baseline platelet CD62P and CD63 expression (p < 0.05); 71 % of PV and 47 % of ET presented with a storage pool disease. Leukocyte CD11b, TF, and PLA were elevated in all patients. TF was higher in PV compared to ET (p < 0.05) and platelet-neutrophil [polymorphonuclear (PMN)] aggregates were increased in ET versus PV (p < 0.05). In ET, PLA were correlated with platelet numbers (p < 0.05). In all patients, JAK2V617F allele burden was directly correlated with monocyte CD11b. Patients with JAK2V617F allele burden >50 % presented higher levels of leukocyte activation. In ET, thrombosis was associated with JAK2V617F mutation (p < 0.05, χ (2) = 5.2), increased monocyte CD11b (p < 0.05) and with platelet-PMN aggregates (p < 0.05). In ET patients, hydroxyurea does not significantly reduce the activation parameters. Our data demonstrate that JAK2V617F allele burden is directly correlated with activation parameters that drive mechanisms that favor thrombosis.

Topics: Adult; Aged; Aged, 80 and over; Alleles; Blood Platelets; Case-Control Studies; CD11b Antigen; Codon; Female; Hemorrhage; Humans; Janus Kinase 2; Male; Middle Aged; Monocytes; Mutation; Neutrophils; Platelet Activation; Platelet Aggregation; Polycythemia Vera; Quinacrine; Thrombocythemia, Essential; Thromboplastin; Thrombosis; Young Adult

The development of thrombosis in polycythaemia vera (PV) involves multifactorial processes including pathological activation of blood cells. Release of microparticles (MPs) by activated cells in diseases is associated with thrombotic risk, but relatively few data are available in PV. The aim of the present study was to investigate the increase in MP release and exposure of phosphatidylserine (PS) on the outer membrane of MP-origin cells in patients with PV, and to analyse their procoagulant activity (PCA). PS-positive MPs and cells were detected by flow cytometry, while PCA was assessed with clotting time and purified coagulation complex assays. We found that PV patients had elevated circulating lactadherin+ MPs, which mostly originating from erythrocytes, platelets, granulocytes, and endothelial cells, as well as increased PS exposing erythrocytes/platelets as compared to secondary polycythaemia patients or healthy controls. These PS-bearing MPs and cells were highly procoagulant. Moreover, lactadherin competed factor V and VIII to PS and inhibited about 90% of the detected PCA in a dose-response manner while anti-TF antibody did no significant inhibition. Treatment with hydroxyurea is associated with a decrease in PS exposure and lactadherin+ MP release of erythrocytes/platelets. Our data demonstrate that PV patients are characterised by increased circulating procoagulant MPs and PS exposing erythrocytes/platelets, which could contribute to the hypercoagulable state in these patients.

Topics: Adult; Aged; Antigens, Surface; Blood Coagulation; Blood Platelets; Cell-Derived Microparticles; Coagulants; Cysteine Endopeptidases; Erythrocytes; Female; Flow Cytometry; Humans; Male; Middle Aged; Milk Proteins; Neoplasm Proteins; Neutrophils; Phosphatidylserines; Polycythemia Vera; Thromboplastin

Recently, the asymmetric distribution of phospholipids in eukaryotic cell membranes has been appreciated and been found to be dependent on the activity of a number of enzymes. The expression of phosphatidylserine (PS), a negatively charged phospholipid, on the platelets of patients with polycythemia vera (P vera) and essential thrombocythemia (ET) was compared to that in normal individuals. The effect of platelet aggregation on PS expression was determined. Exposure of PS on platelets obtained from patients with P vera and ET and from age- and sex-matched healthy volunteers was measured by fluorescein-labeled Annexin V binding to platelets and by the platelets' thrombin-generating capacity determined by the prothrombinase assay. PLatelet prothrombinase activity (mean +/- standard deviation [SD]), as measured by thrombin generation, was 2.32+/-2.2 micro/mL in the P vera group and 1.55+/-1.0 micro/mL in the control group (p=0.3). PS expression as measured by Annexin V binding (mean +/- SD) was 2.6+/-2.4 % in the P vera group versus 1.55+/-1.2% among controls (p=0.03). In the ET group, prothrombinase activity (mean +/- SD) was 1.0+/-0.6 micro/mL and 2.1+/-0.9 micro/mL in the control group (p=0.006). Annexin V binding (mean +/- SD) was 4.8+/-4.2% in the ET group and 2.77+/-2.1% among control subjects (p=0.09). When the prothrombinase assay was performed after addition of adenosine diphosphate (ADP) to the platelets, there was a significant increase in thrombin generation in the myeloproliferative disorder (MPD) group (3.1+/-2.0 micro/mL) compared to the thrombin generated by unstimulated myeloproliferative disorder platelets (2.07+/-1.69 micro/mL) (p=0.0006). An increase in thrombin generation was seen in the ADP-stimulated platelet samples in all ten paired samples studied. Likewise, the addition of ADP to control platelets increased thrombin generation from 2.0+/-1.0 micro/mL in unstimulated platelets to 4.3+/-1.6 micro/mL in ADP-treated platelets (p=0.0006). Thrombin generation increased in all of the ADP-stimulated platelet samples compared to the untreated platelets. There was however, no difference in the increased thrombin generation when ADP-stimulated platelets from MPD patient and control subjects were compared (p=0.3). Results indicate that some patients with MPDs may show increased PS expression on platelet surface. When analyzed overall, there was a tendency toward greater PS expression in the P vera and ET patient groups; however, the increase d

Topics: Adenosine Diphosphate; Annexin A5; Blood Platelets; Enzyme Activation; Female; Humans; Male; Membrane Lipids; Phosphatidylserines; Platelet Aggregation; Polycythemia Vera; Prothrombin; Thrombin; Thrombocythemia, Essential; Thromboplastin

Polycythemia vera (PV) is associated with a high incidence of thrombosis. The association of apparent and secondary polycythemia with thrombosis is not clear. It was suggested that activation of the coagulation system contributes to thrombus formation in PV. However, the mechanism of activation is unknown. Monocytes generate a potent tissue factor (TF) upon stimulation with various substances, which is involved in thrombus formation in various disorders. Therefore, we studied the possibility that the factor is involved in the activation of coagulation and thrombus formation also in PV. Unstimulated peripheral blood mononuclear cells (PBMC) from each of the different types of polycythemia expressed weak TF activity (2 U) and antigen (41.4 to 52.9 pg/ml), which were similar to normal controls. Following stimulation with endotoxin, PBMC from normal controls and from apparent and secondary polycythemia showed a 3.9- to 4.5-fold increase in TF, while cells from PV showed a 21-fold increase (P<0.001). Similar levels were generated by PBMC after treatment of PV and at the spent phase. TF was generated by monocytes but not by lymphocytes. Plasma prothrombin fragment1+2 (F1+2) levels, assayed at the same time, were significantly higher in PV (2.46 nm) compared to normals and apparent and secondary polycythemia (0.22 to 0.32 nm), and were in a significant correlation with monocyte TF activity and antigen levels (r = 0.77, 0.87). The high levels of F1+2 confirm that the coagulation system is activated in PV. The increased capacity of monocytes to generate TF may be responsible for the activation of the coagulation system and thrombus formation. The hypercoagulability state that is induced by this mechanism suggests that long-life oral anticoagulation should be considered once thrombosis has been developed in PV.

Topics: Adult; Aged; Blood Coagulation; Humans; Middle Aged; Monocytes; Peptide Fragments; Polycythemia Vera; Prothrombin; Thromboplastin

Topics: Adolescent; Adult; Aged; Antineoplastic Agents; Blood Coagulation Tests; Blood Platelets; Female; Humans; Leukemia, Erythroblastic, Acute; Leukemia, Myeloid; Male; Middle Aged; Myeloproliferative Disorders; Platelet Adhesiveness; Polycythemia Vera; Primary Myelofibrosis; Thromboplastin

Topics: Adult; Blood Cell Count; Blood Coagulation Tests; Blood Platelet Disorders; Blood Platelets; Cholesterol; Erythrocyte Count; Female; Hematocrit; Hemoglobinometry; Humans; Lipids; Male; Middle Aged; Phospholipids; Polycythemia Vera; Thromboplastin

Topics: Anemia, Macrocytic; Blood Platelet Disorders; Blood Platelets; Chromatography, Paper; Female; Humans; In Vitro Techniques; Ovarian Diseases; Phospholipids; Polycythemia Vera; Primary Myelofibrosis; Prothrombin; Thrombin; Thromboplastin; Uremia

Topics: Blood Coagulation Tests; Humans; Polycythemia Vera; Thromboplastin

Topics: Adolescent; Blood Coagulation Tests; Blood Platelets; Child; Cholecystitis; Coronary Disease; Duodenal Ulcer; Geriatrics; Glycine max; Hemophilia A; Humans; Lecithins; Myocardial Infarction; Phosphatidylcholines; Polycythemia Vera; Thrombophlebitis; Thromboplastin