Erythropoietin-dependent primary pure erythrocytosis.

We investigated the pathogenesis of isolated erythrocytosis of 14 yr duration in a 28-yr-old man. The increase in red cell mass was attributed to increased erythropoietin production. An extensive search for recognized causes of secondary erythrocytosis was unrevealing. Family members were found to be hematologically normal. After reduction of the circulating red cell mass by 20%, erythropoietin activity nearly quadrupled, thus suggesting a normal erythropoietin response to phlebotomy. When bone marrow cells of the patient were cultured in plasma clots in the absence of added erythropoietin, endogenous erythroid colony formation was observed, a pattern previously believed to be specific for polycythemia vera bone marrow cells. Our observations suggest that the erythrocytosis in this individual is best explained by an abnormal "servoregulatory" mechanism of erythropoietin production. In addition, this is the first instance in which the rule that endogenous erythroid colony formation is correlated with the diagnosis of polycythemia vera has not held.     

Polycythemia and the Budd-Chiari syndrome: study of serum erythropoietin and bone marrow erythroid progenitors

The mechanism of polycythemia associated with the Budd-Chiari syndrome is unknown. Erythropoiesis in 10 patients with Budd-Chiari syndrome was studied in an attempt to distinguish prior unrecognized polycythemia vera from secondary polycythemia. Serum erythropoietin was assayed using a mouse fetal liver erythroblast assay. High concentrations of serum erythropoietin were observed in 6 of 7 patients with acute primary Budd-Chiari syndrome. Levels were normal in four patients who were investigated during the chronic phase and were increased in one with persisting polycythemia. In one patient, erythropoietin concentration in the hepatic vein was twice the level measured in peripheral, caval and renal venous blood. Bone marrow erythroid progenitors developed in vitro in the absence of exogenous erythropoietin in all polycythemia vera cases studied in acute and chronic phases, whether polycythemia persisted or not. These findings indicate that hepatic erythropoietin production occurs in the acute phase of Budd-Chiari syndrome and suggest that, in some cases of Budd Chiari syndrome, polycythemia which resolves after the acute phase may be secondary to liver disease.     

Polycythemia vera with der(15) and der(20) associated with remarkable neutrophilia]

An autopsy case of polycythemia vera with der(15) and der(20) associated with remarkable neutrophilia was reported. A 87-year-old man was diagnosed as polycythemia vera in August 1987. The red blood cell count was 621 x 10(4)/microliters, Ht 58.5% and the white blood cell count 45,400/microliters with 92% neutrophils. The splenomegaly, increased red blood cell volume and the low erythropoietin level were present. The arterial SaO2 value was above 92%. The chromosome analysis of bone marrow cells revealed 46, XY, -15, -20, +der(15)t(15;?)(q13-15;?), +der(20)t(20;?)(q11;?). The breakpoint in No. 20 was in q11. The remarkable leukocytosis with relative and absolute neutrophilia were observed. Particularly late in the clinical course the white blood cell count was 92,900/microliters with 99% neutrophils. The Ph1 chromosome was negative and the bcr rearrangement was not detected. He died of bronchopneumonia in January 1989. At the autopsy findings neither the marrow fibrosis nor the extramedullary leukemic cell infiltration was noticed.     

Endogenous erythroid colony formation by peripheral blood mononuclear cells from patients with myelofibrosis and polycythemia vera.

Peripheral blood mononuclear cells from patients with polycythemia vera or myelofibrosis with myeloid metaplasia were studied for their erythroid colony growth characteristics in plasma clot cultures. In both diseases, erythroid colonies formed early in culture in the absence of added erythropoietin (endogenous colonies). In no instance did early, endogenous colony formation occur with peripheral blood cells from normals or patients with secondary polycythemia. A normal response to erythropoietin was observed with both control and patients' peripheral blood cells. Spleen mononuclear cells obtained from one patient with myelofibrosis also produced endogenous colonies and showed a response to erythropoietin. This study suggests that culture of peripheral blood mononuclear cells might serve as a useful tool in discriminating polycythemia vera from secondary polycythemia.     

Regulation of Erythropoiesis. I. Erythropoietin Assay as a Clinical Tool

An erythropoietin assay using hypertransfused rats and radioiron utilizationhas been evaluated in regard to modifying factors and its variability. It isproposed that the dose-response relationship may be regarded as an adsorptiveprocess which suggests new investigative approaches in terms of hormonebinding sites and erythropoietin inhibition.

Elevated levels of erythropoietin were found in 14 of 16 patients withrefractory anemia indicating a basic defect in the response of the erythroidmarrow. The two exceptions are of great theoretical interest, but insufficientinformation limits further conclusions. Patients with hypoxic polycythemiademonstrated increased levels only when their compensatory equilibrium hadbeen modified by phlebotomy. Seven patients with polycythemia vera haderythropoietin levels within the normal range whether or not therapy hadmodified their red cell mass. This is further evidence that polycythemia vera isa proliferative disorder usurping the normal regulation. The clinical use oferythropoietin assay may provide the most information when correlated withalterations of oxygen-carrying capacity as a functional test of the patient’serythropoietic regulatory mechanism.

Submitted on February 5, 1962 Accepted on March 23, 1962     

Mixed myeloid—lymphoid colonies in a patient with polycythemia vera

Peripheral blood mononuclear cells from a patient with polycythemia vera were cultured in a methylcellulose system employing human serum. Electron microscopy documented the appearance of mixed colonies containing lymphocytes, granulocytes, megakaryocytes, and erythrocytes. In vitro culture characteristics were similar to those seen for other patients with polycythemia vera, ie, colonies grew in the absence of added erythropoietin or other pathway-specific regulators. Plating efficiency was linearly related to the number of cells plated, which supports the concept that each colony arose from a single cell. The appearance of mixed myeloid—lymphoid colonies points to the existence of a primitive stem cell capable of giving rise to multiple hematopoietic cell lines.     

Erythropoietin-producing renal cyst and polycythemia vera. Clarification of their relationship

Described here is a patient with the splenomegaly, pancytosis and panhyperplastic marrow of polycythemia vera who was found to have bilateral renal cysts. Erythropoietin levels in the serum and in fluid from the cyst on the left kidney were elevated. After puncture, fluid aspiration and injection of a sclerosing solution into the cyst on the left kidney, the serum erythropoietin level became undetectable. Subsequent puncture of the cyst on the right kidney showed no erythropoietin activity in the cyst fluid. However, the patient's signs of polycythemia vera persisted. Specimens of the patient's marrow grown in vitro showed a lack of response to erythropoietin stimulation, characteristic of polycythemia vera. This case, with defined diagnostic criteria and erythropoietin levels before and after therapy, suggests that the association of renal cysts and pancytosis is coincidental, as opposed to the documented endocrinologic relationship between secondary erythrocytosis and erythropoietin-producing renal lesions. In eight cases of concomitant pancytosis and renal cysts, described in the literature, the question of a causal versus a coincidental relationship was raised but unanswered.     

Overexpression of microRNA-16-2 contributes to the abnormal erythropoiesis in polycythemia vera

Deregulated expression of microRNAs is associated with neoplasia. Here, we show that mature miR-16 levels are abnormally increased in CD34(+) cells of patients with polycythemia vera as a consequence of preferential expression of miR-16-2 on chromosome 3 rather than of miR-16-1 on chromosome 13. Forced expression of miRNA-16 in normal CD34(+) cells stimulated erythroid cell proliferation and maturation. Conversely, exposure of polycythemia vera CD34(+) cells to small interfering RNA against pre-miR-16-2 reduced erythroid colonies and largely prevented formation of erythropoietin-independent colonies; myeloid progenitors remained unaffected. Experiments with knock down of JAK2 indicated that overexpression of miR-16 was independent of JAK/STAT pathway activation. Mice injected with an miR-16 antagomir showed a blunted erythroid response to exogenous erythropoietin, which indicates a role of miR-16 in normal erythropoiesis. These data suggest that deregulation of miR-16-2 contributes to abnormal expansion of erythroid lineage in polycythemia vera. However, the mechanisms for miR-16-2 overexpression remain to be elucidated, because no genetic abnormalities at the miR-16-2 locus were discovered.     

Polycythemia vera--a case report and discussion on pathogenic mechanisms of increased thrombosis

Polycythemia vera is a myeloproliferative disorder characterized by increased red cell mass and frequently complicated by venous and arterial thrombosis. The mechanism underlying the increased incidence of thrombotic events remains illusive. Presented in this report are a case of a 77-year-old man diagnosed with polycythemia vera and a review of the current literature on the mechanisms underlying the increased incidence of thrombotic events in polycythemia vera.     

Pathogenesis of polycythemia vera—new concepts

Data presently available suggest that polycythemia vera is an acquired clonal disorder of the pluripotent stem cell resulting in expansion of committed stem cell pools, most prominently in the erythroid line. In vitro and in vivo studies suggest that erythropoiesis in polycythemia vera is at least partially modulated by erythropoietin.     

Sequential development of chronic lymphocytic leukemia in a patient with polycythemia vera

A patient with a seven-year history of polycythemia vera treated by repeated phlebotomies and intermittent busulfan administration developed gradually lymphocytosis accompanied by thrombocytopenia in peripheral blood and in the bone marrow. A marked pathological monoclonal proliferation of the B-cell population was detected. The sequential development of chronic lymphocytic leukemia in the patient with polycythemia vera could be considered as a coincidence because there is no reliable explanation of this event at present.     

Apoptosis and polycythemia vera

Polycythemia vera is an acquired clonal myeloproliferative disorder characterized by increased numbers of erythroid cells, often with a concomitant rise in neutrophils and/or megakaryocytes. Normally, erythropoietin is essential for the survival and proliferation of erythroid progenitors; however in polycythemia vera the erythroid progenitor cells can survive and develop in the absence of erythropoietin. Members of the Bcl-2 family of apoptosis regulators have been shown to mediate the erythropoietin-dependent survival of erythroid cells. In this article, recent advances in understanding the mechanisms used by erythroid progenitors from patients with polycythemia vera to control apoptosis, are discussed.     

Differentiation between essential thrombocythemia and polycythemia vera with marked thrombocytosis

Accurate distinction between essential thrombocythemia and thrombocytotic polycythemia vera requires determination of the red cell mass in the presence of adequate iron stores, but this is not always possible. We therefore compared the clinical and laboratory features at the time of presentation of 50 patients with unequivocal essential thrombocythemia and 27 patients with thrombocytotic polycythemia vera. Univariate analysis failed to identify any single parameter capable of reliably separating the groups. A logistic regression algorithm incorporating hematocrit, white cell count, and spleen size markedly increased the diagnostic accuracy (92%) compared with predictions based on the hematocrit alone (52%). The algorithm's usefulness for patients with intermediate hematocrits was confirmed by analysis of independent samples of essential thrombocythemia and thrombocytotic polycythemia vera patients, and also by analysis of patients with probable essential thrombocythemia in whom the diagnosis could not be confirmed because of inadequate exclusion of polycythemia vera. Furthermore, comparison of survival data suggests that differentiating these disorders is prognostically important. The algorithm is recommended as an alternate method for differentiating essential thrombocythemia from thrombocytotic polycythemia vera whenever the red cell mass is unavailable or iron deficiency cannot be excluded.     

Red cell mass measurement in patients with clinically suspected diagnosis of polycythemia vera or essential thrombocythemia

The cut off for hemoglobin or hematocrit that indicates the need for an isotopic red cell mass study was investigated in 179 patients with a presumptive diagnosis of polycythemia vera or essential thrombocythemia. Hematocrit showed better diagnostic accuracy than hemoglobin. Hemoglobin over 18.5 g/dL in males or over 16.5 g/dL in females showed a high specificity indicating that red cell mass study could be avoided in such cases, but it showed low sensitivity leading to 46% false negatives. The best value of hematocrit to indicate a red cell mass study was 0.50 L/L in males (specificity 75%, sensitivity 87.5%) and 0.48 L/L in females (specificity 73%, sensitivity 94%). Lowering the hematocrit threshold to 0.48 L/L in males increased sensitivity up to 95%. A red cell mass study should be performed in patients with suspected diagnosis of essential thrombocythemia or polycythemia vera and with hematocrit between 0.48 L/L and 0.52 L/L.Key words: polycythemia vera, essential thrombocythemia, red cell mass, hemoglobin, hematocrit     

Plasma erythropoietin in polycythemia.

Erythropoietin titers of plasma cannot be used to differentiate polycythemia vera from secondary polycythemia since the limit of sensitivity of our current bioassay technics is 50 mU, considerably higher than levels found in normal subjects and in patients with polycythemia. However, erythropoietin is relatively heat stable, and since abundant plasma is available from therapeutic phlebotomies it is possible to prepare and assay highly concentrated, erythropoietin-containing extracts. In 35 normal subjects, erythropoietin levels ranged from less than 5 mU/ml (the limit of sensitivity) to 18 mU/ml with a mean of 7.8 mU/ml. In 21 patients with proved polycythemia vera, the levels were less than 5 mU/ml in all. In 41 patients with suspected secondary polycythemia or polycythemia of unknown origin, the levels ranged from less than 5 to 3,000 mU/ml. Three of the 11 patients with levels less than 5mU/ml were subsequently shown to have polycythemia vera. These results suggest that this refinement of the routine bioassay for erythropoietin may be of clinical importance in the differential diagnosis of polycythemia.     

Hemoglobin Villejuif [beta 123(H1) Thr----Ile]: a new variant found in coincidence with polycythemia vera

A new abnormal hemoglobin, Hb Villejuif [beta 123(H1) Thr----Ile] has been discovered during the exploration of a polycythemia in a 87-year-old patient of French origin. The isoelectric focusing of the lysate revealed the presence of a variant hemoglobin with an isoelectric point very close to that of HbA. The oxygen binding properties of the patient's red blood cells being normal, it was clear that the polycythemia was not a consequence of the presence of this hemoglobin. In fact, the red blood cell morphology and the involvement of the other blood cell lines, demonstrating excessive hemopoiesis, led to the diagnosis of polycythemia vera.     

Erythrocytosis associated with renal artery thrombosis in a patient with polycystic kidney disease on hemodialysis

We report a case of erythrocytosis in a patient with end-stage renal failure on chronic hemodialysis. The patient with polycystic kidney disease had an average Hb level of 10 g/dl while on hemodialysis for 3 years. He developed erythrocytosis (Hb 17.6 g/dl) following a cadaveric renal transplantation. No signs suggesting polycythemia vera were found. Nonrenal causes of secondary erythrocytosis such as anoxia, hemoglobinopathies or tumors were excluded. Angiography showed renal artery occlusion of the native kidney. Serum erythropoietin level was 85 U/l (normal 52 +/- 31 U/l) as measured by 3H-thymidine uptake. It is suggested that ischemia caused by the renal artery thrombosis stimulated the erythropoietin production in the native polycystic kidney.     

Intracellular growth factors in polycythemia vera and other myeloproliferative disorders.

In polycythemia vera, idiopathic myelofibrosis, and essential thrombocytosis, hematopoietic cell proliferation is increased in the absence of a recognizable stimulus, suggesting the autonomous production of growth factors in these disorders. Sonicates of peripheral blood mononuclear cells (PBMNC) from patients with polycythemia vera, idiopathic myelofibrosis, and essential thrombocytosis contained soluble factors that stimulated the proliferation of quiescent-confluent 3T3 cells. PBMNC sonicates from normal individuals; from patients with secondary erythrocytosis, chronic myelogenous leukemia, B-cell chronic lymphocytic leukemia, and acute myelogenous leukemia; and from K-562 and HL-60 cells did not stimulate proliferation. Polycythemia vera PBMNC sonicates also induced anchorage-independent colony formation in soft agar by normal rat kidney fibroblasts. Both the mitogenic and transforming activities of the polycythemia vera PBMNC sonicates resided in the T-lymphocyte-depleted mononuclear fraction of the PBMNC and were not secreted. By gel filtration, reversed-phase HPLC and NaDodSO4/PAGE, the mitogenic and transforming activities in the polycythemia vera PBMNC were localized to three proteins with molecular masses of 13-, 17-, and 65-kDa. The 13-kDa protein was only mitogenic, and the 17-kDa protein was only transforming, whereas the 65-kDa protein had both mitogenic and transforming activity. These proteins may be involved in the autonomous hematopoiesis that characterizes polycythemia vera, idiopathic myelofibrosis, and essential thrombocytosis.     

Granulocyte Kinetic Studies in Patients with Proliferative Disorders of the Bone Marrow

Granulocyte kinetic studies with DFP³² were done in four patients withchronic myelocytic leukemia, three patients with polycythemia vera, one patient with essential thrombocythemia, and one patient with persistent, unexplained granulocytosis. The increased blood granulocyte concentrationfound in the patients with polycythemia vera, essential thrombocythemia andunexplained granulocytosis was at least in part the result of increased granulocyte production. Precise calculations of granulocyte pool sizes and turnoverrates in the patients with chronic myelocytic leukemia were not possiblebecause of unresolved problems related to the non-uniform population ofmyeloid cells in the blood of these patients. However, within the limitationsof the method, a greater number of myeloid cells were turned over per daythrough blood than in normal subjects. The findings support the conceptthat a widespread disorder of marrow proliferation exists in chronic myelocytic leukemia, polycythemia vera, and essential thrombocythemia.

Submitted on December 20, 1962 Accepted on March 23, 1963