Erythropoietin receptors in polycythemia vera.

The role of erythropoietin (EP) in polycythemia vera (PV) is controversial, with some experiments suggesting that erythroid progenitors in PV are exquisitely sensitive to EP and EP dependent, and others suggesting that PV progenitors are EP independent. We have examined the characteristics of the EP receptor (EP-R) on erythroid colony-forming cells (ECFC) from patients with PV. In contrast to normal ECFC, which have two classes of EP-R, with 20% showing high affinity (Kd = 0.13 nM; range, 0.04-0.20 nM) and the remainder lower affinity (Kd = 0.37 nM; range, 0.28-0.57 nM), PV ECFC show a single class of 851 low affinity EP-R with Kd = 0.72 nM (range, 0.36-0.85 nM). ECFC from patients with secondary (EP driven) polycythemia or anemia show two classes of EP-R (Kd = 0.18 and 1.10 nM, respectively). Attempts to remove tightly bound EP from putative high affinity EP-R in PV did not reveal any higher affinity receptors. Determination of molecular size by crosslinking showed two proteins of 90 and 100 kD similar to those seen with normal EP-R. These studies indicate the PV ECFC have EP-R that are structurally similar to normal EP-R but lack the higher binding affinity for EP.

Polycythemia vera blood burst-forming units-erythroid are hypersensitive to interleukin-3.

Because polycythemia vera (PV) is a clonal hematopoietic stem cell disease with a trilineage hyperplasia, and interleukin-3 (IL-3) stimulates trilineage hematopoiesis, we have studied the response of highly purified PV blood burst-forming units-erythroid (BFU-E) to recombinant human IL-3 (rIL-3). Whereas the growth of normal blood BFU-E in vitro rapidly declined by 40 and 60% after 24 and 48 h of incubation without 50 U/ml of rIL-3, the growth of PV BFU-E declined by only 10 and 30% under the same conditions, demonstrating a reduced dependence on rIL-3. A reduced dependence of PV BFU-E on recombinant human erythropoietin (rEP) was also present. Dose-response experiments showed a 117-fold increase in PV BFU-E sensitivity to rIL-3, and a 6.5-fold increase in sensitivity to rEP, compared to normal BFU-E, whereas blood BFU-E from patients with secondary polycythemia responded like normal BFU-E. Endogenous erythroid colony (EEC) formation, which is independent of the addition of rEP, was reduced by 50% after erythroid colony-forming cells were generated from PV BFU-E in vitro without rIL-3 for 3 d, whereas rEP-stimulated erythroid colonies were unaffected. These studies demonstrate a striking hypersensitivity of PV blood BFU-E to rIL-3, which may be the major factor in the pathogenesis of increased erythropoiesis without increased EP concentrations.

Isolation and characterization of a novel vitamin B12-binding protein associated with hepatocellular carcinoma.

High levels of a novel vitamin B12-binding protein (hepatoma B12 BP) have been observed recently in plasma obtained from three adolescent patients with hepatocellular carcinoma. This protein has now been isolated in homogeneous form from the plasma and pleural fluid of two of these patients by the use of affinity chromatography with vitamin B12-Sepharose. The hepatoma B12 BP belongs to the R-type group of B12-binding proteins and is essentially indistinguishable from the recently isolated human milk and saliva R-type proteins in terms of: (a) immunologic properties based on immunodiffusion and immunoprecipitation assays; (b) amino acid composition; (c) molecular weight based on amino acid and carbohydrate content; and (d) absorption spectra. Both hepatoma B12 BPs contain more sialic acid and less fucose than the milk and saliva B12 BPs. All four proteins contain similar amounts of galactose, mannose, galactosamine, and glucosamine. Differences in sialic acid content appear to account for the differences in electrophoretic mobility that were observed among the four proteins. Differences in total carbohydrate content appear to account for the differences in apparent molecular weight that were observed with both gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Tumor tissue from one of the patients contained 10 times as much R-type protein as did normal liver tissue from the same patient. This suggests, although it does not prove, that synthesis by the tumor is the cause of the high levels of R-type protein found in the plasma of certain patients with hepatocellular carcinoma. Plasma survival studies performed with rabbits indicate that the hepatoma B12 BP has a prolonged plasma survival and suggests that his parameter is also of importance.

L-Ethionine as an inducer of differentiation in human promyelocytic leukemia cells (HL-60).

The methionine analog, L-ethionine, induces morphological and biochemical changes in cultured HL-60 cells which are indicative of myeloid maturation. After 3 to 5 days of growth in the presence of L-ethionine, the majority of cells have enhanced phagocytic ability. The percentage of cells in the culture which bear complement receptors and which can respond to 12-O-tetradecanoylphorbol-13-acetate with respiratory burst activity increases more than 3-fold. Since the cells fail to become adherent and lose nonspecific esterase activity, we conclude that L-ethionine, like dimethyl sulfoxide, induces granulocytic differentiation of HL-60 cells.

Current management in polycythemia vera.

Myeloproliferative diseases (MPD) include polycythemia vera (PV), essential thrombocythemia, agnogenic myeloid metaplasia, and chronic myelogenous leukemia. The focus of this report is on PV, which is characterized by an increase in red blood cells, granulocytes, and platelets. Complications associated with PV are an increased risk of thrombosis and abnormal bleeding. Phlebotomy to a hematocrit less than 45% is the mainstay of treatment for erythrocythemia, but may further increase the platelet count, necessitating the use of a platelet-lowering agent in conjunction with phlebotomy. Other treatment strategies include low-dose aspirin or other antithrombotic therapy and cytoreduction. Mounting evidence of the leukemogenicity and mutagenicity of radioactive phosphorus and alkylating agents, as administered using "conventional" regimens, has restricted the liberal use of these treatments. Three drugs have emerged as useful because of their efficacy in reducing the elevated platelet count: anagrelide, hydroxyurea (HU), and interferon alfa (IFN). It is clear that no single agent satisfies all the needs for cytoreduction that arise during the course of PV. Future protocols should be designed that draw on the large body of experience already gained with these drugs to transcend the limitations of single-agent therapy and to improve quality of life as well as survival. Semin Hematol 38(suppl 2):25-28.

Historical perspective on the treatment of essential thrombocythemia and polycythemia vera.

Since 1970, the treatment of essential thrombocythemia (ET) and polycythemia vera (PV) has evolved from alkylating agents to hydroxyurea (HU), and more recently to agents such as interferon-alpha (IFN) and anagrelide. While the earlier treatments for ET and PV have been successful in varying degrees, diagnosis of these disorders is being made earlier and in populations deemed at lower risk, but who may suffer greatly from the toxicity of long-term treatment with these agents. Thus, the risks and benefits of treatment versus nontreatment and between types of therapy have created a need for treatments that are safer for more people for greater lengths of time.

The effect of chronic hypocholesterolemia in myeloproliferative disease on the distribution of plasma and erythrocyte tocopherol.

The presence of hypocholesterolemia and increased erythrocyte lipid peroxidation susceptibility in myeloproliferative disorders raised the possibility of coexistent tocopherol deficiency. Plasma and red blood cell (RBC) alpha-tocopherol, beta- + gamma-tocopherol, and free cholesterol were determined simultaneously by high performance liquid chromatography in 22 patients and 26 controls. Plasma alpha-tocopherol was correlated most highly with plasma free cholesterol and secondarily with RBC alpha-tocopherol in both groups. Plasma-free cholesterol and alpha-tocopherol were significantly reduced in myeloproliferative disease, although the ratio between the two remained normal. Erythrocyte tocopherol and free cholesterol concentrations were normal in myeloproliferative disease. High relative retention of tocopherol by erythrocytes was most pronounced in patients with the lowest plasma alpha-tocopherol and free cholesterol levels. The normal RBC tocopherol levels in these patients with chronic hypocholesterolemia indicate that the observed increase in RBC peroxidation susceptibility is not explainable by a deficiency of RBC vitamin E.

Failure of mean red cell volume to serve as a biologic marker for alcoholism in narcotic dependence. A randomized control trial.

Mean red cell volume, mean red cell hemoglobin, and mean red cell hemoglobin concentration were measured in a prospective, longitudinal, single-bind study of alcoholism and its treatment in 625 patients receiving methadone. Mean red cell volume and mean red cell hemoglobin were significantly elevated in alcoholic as compared with nonalcoholic patients (p less than 0.001), with a sensitivity of 40 and 51 percent, respectively. The ability of an elevated mean red cell volume and mean red cell hemoglobin to exclude active alcoholism (specificity) was 86 and 76 percent, respectively. Development of excessive consumption of alcohol during the course of the study was not associated with significant elevations over baseline values of either mean red cell volume or mean red cell hemoglobin. Similarly, the mean red cell volume and mean red cell hemoglobin in the small number of patients whose consumption of alcohol markedly decreased did not significantly change from baseline values. These findings suggest that although the specificity of mean red cell volume may be helpful in eliminating those persons who are not actively alcoholic, its sensitivity does not permit its use as a biologic marker for alcoholism. The inclusion of an elevated mean red cell volume as a major criterion for the diagnosis of alcoholism should be reconsidered.

Characterization of hypocholesterolemia in myeloproliferative disease. Relation to disease manifestations and activity.

Characterization of the hypocholesterolemia observed in polycythemia vera and agnogenic myeloid metaplasia revealed significant reductions in plasma total cholesterol, low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol in an age- and sex-matched comparison with the Framingham population. Men with myeloproliferative disease also had significantly lower total and LDL cholesterol levels than did those with relative or secondary polycythemia. LDL and HDL cholesterol were significantly correlated, suggesting a generalized disturbance of cholesterol metabolism, unexplained by nutritional status. Evaluation of the relationship among hematic cell proliferation, degree of myeloid metaplasia and hypocholesterolemia by multiple regression analysis revealed that spleen size was the variable of most significance in explaining the variation in plasma total, LDL and HDL cholesterol levels. Uncontrolled disease activity was accompanied by a decline in LDL cholesterol levels. Splenectomy or control of proliferation with chemotherapy or splenic irradiation reversed this abnormality. Levels of plasma total and lipoprotein cholesterol provide information that may be of value in diagnosis and assessment of myeloproliferative disease activity.

High-density lipoprotein cholesterol is reduced in patients with sarcoidosis.

PURPOSE: Sarcoidosis is a disease in which the proliferation of monocyte-macrophage-derived cells is observed. In other diseases characterized by expansion of the monocyte-macrophage system, such as Gaucher's disease and myeloid metaplasia, abnormalities of lipoprotein metabolism have been demonstrated. To determine whether similar abnormalities in lipoprotein cholesterol concentrations could be identified in patients with sarcoidosis, we studied total cholesterol, low-density lipoprotein (LDL) cholesterol, and high-density lipoprotein (HDL) cholesterol as well as triglyceride levels in 52 patients with biopsy-proven sarcoidosis. PATIENTS AND METHODS: Patients had no other medical disorders and were not being treated with corticosteroids or antimalarial agents. Blood samples were collected by venipuncture after an overnight fast. Plasma total cholesterol and triglyceride levels were measured using enzymatic techniques. Lipoprotein cholesterol was quantified by lipoprotein fractionation. HDL cholesterol was measured as cholesterol remaining in the supernatant after precipitation of LDL and very-low-density lipoprotein from whole plasma by the heparin-maganese chloride method. Computation was used to determine the level of LDL cholesterol. RESULTS: We found significantly reduced levels of total cholesterol (183.9 +/- 27.6 versus 194.3 +/- 16.5 mg/dl, mean +/- SD, p = 0.021) and HDL cholesterol (41.2 +/- 13.0 versus 51.9 +/- 6.1 mg/dl, p = 0.0001) in sarcoid patients versus an age-, sex-, and race-matched reference group. Differences were not observed in triglyceride or LDL cholesterol levels (p greater than 0.05). CONCLUSION: These findings are similar to those observed in the myeloproliferative diseases, Gaucher's disease, and rheumatoid arthritis and suggest a functional role for monocytes-macrophages in the regulation of serum lipoprotein cholesterol levels.

Comparison of erythroid progenitor cell growth in vitro in polycythemia vera and chronic myelogenous leukemia: only polycythemia vera has endogenous colonies.

The ability of erythroid cultures to distinguish among myeloproliferative disorders was examined. We studied 14 patients with polycythemia vera (PV), 11 with chronic myelogenous leukemia (CML), four with non-PV erythrocytosis, two with agnogenic myeloid metaplasia, as well as three normal fetuses and greater than 25 normal adults. Endogenous, i.e. grew without added erythropoietin, bone marrow CFU-E-derived colonies were observed in all but one PV patient. However, endogenous blood BFU-E-derived bursts were observed in only eight of 14 PV patients. Endogenous erythroid colonies were not seen in cultures from any normal adults or fetuses, or patients with CML, erythrocytosis, or myeloid metaplasia. In PV, relative HbF synthesis was always greater in cultures without erythropoietin, while in cultures from all other patients relative HbF synthesis was similar to that observed in cultures from normal individuals. We conclude that PV and CML are distinguishable in culture since CML patients do not have endogenous growth. Most important, endogenous bone marrow CFU-E-derived colonies are the only consistently unique observation in patients with PV, and endogenous CFU-E- and BFU-E-derived colonies and bursts are not uniformly observed in PV blood cultures. In-vitro studies of erythropoiesis to confirm the diagnosis of PV, therefore, require marrow when endogenous colonies and bursts are absent from blood cultures.

Altered high density lipoprotein metabolism in patients with myeloproliferative disorders and hypocholesterolemia.

Patients with the myeloproliferative disorders (MPD), myeloid metaplasia and polycythemia vera, have significantly reduced concentrations of plasma low density (LDL) and high density (HDL) lipoprotein cholesterol (C). We have previously demonstrated that increased catabolism of LDL was associated with the low LDL-C levels. In the present study we have determined the rates of synthesis and removal of apolipoprotein A-1 (apoA-1) in five subjects with MPD who had markedly reduced HDL-C concentrations (18.2 +/- 4.1 mg/dL). Their results were compared to those obtained in six subjects with hypertriglyceridemia (HTG) with similar levels of HDL-C (19.7 +/- 3.9 mg/dL) and five subjects with normal (N) HDL-C concentrations (49.6 +/- 7.4 mg/dL). The results demonstrated that the fractional catabolic rate (FCR) for apoA-1 was significantly increased in the MPD group v N (0.38 +/- 0.15 v 0.21 +/- 0.03 day-1, P less than 0.05) while the synthetic rates for apoA-1 were similar in the two groups. The FCR for apoA-1 in the HTG group (0.36 +/- 0.07 day-1) was nearly identical to that in the MPD group, in spite of the large differences in their plasma triglyceride concentrations (406.2 +/- 217.9 v 117.0 +/- 29.8 mg/dL, P less than 0.05). Compositional studies indicated that the HTG group had very cholesterol depleted HDL while the HDL particles in the MPD group appeared to have a normal cholesterol content. These studies indicate that subjects with MPD have striking increases in HDL catabolism that can account fully for their markedly reduced levels of HDL cholesterol. The pathophysiologic mechanisms that are the basis of this alteration remain to be determined.

Effects of acute endotoxemia and glucose administration on circulating leukocyte populations in normal and diabetic subjects.

Effects of intravenous endotoxin and glucose administration on circulating leukocyte populations were compared in seven normal subjects and seven patients with juvenile-onset diabetes by means of automated cytochemical differential counting to quantitate each cell type. Both groups had comparable control cell counts that were unaffected by glucose tolerance testing but altered significantly by endotoxin. Different patterns of response to endotoxin were observed for different circulating cell types. The response of diabetics was parallel to that of normals but showed lower neutrophil and monocyte rebound, longer lasting depression of lymphocytes and eosinophils, and greater rebound of basophils on the day following endotoxin exposure. Characterization of distinctive normal response patterns of circulating leukocyte populations to endotoxin and comparison with responses in diabetes revealed abnormalities under conditions of stress that may impair the diabetic's ability to cope with acute infection.

Diagnosis and treatment of thrombocythemia in myeloproliferative disorders.

Myeloproliferative disorders originate in the clonal expansion of a transformed pluripotential hematopoietic progenitor cell. This results in a group of syndromes that include polycythemia vera, essential thrombocythemia, chronic myelocytic leukemia, and agnogenic myeloid metaplasia. Diagnostic criteria forpolycythemia vera and essential thrombocythemia were codified by the Polycythemia Vera Study Group in 1967 and 1977. Subsequent modifications include criteria for evidence of clonal proliferation by abnormal bone marrow karyotype and demonstration of erythropoietin-independence of erythropoiesis or reduced serum erythropoietin. Phlebotomy is the mainstay of treatment for polycythemia vera. The defining characteristic of essential thrombocythemia is a sustained elevation of the platelet count above 600,000/microL in an untreated patient. Symptoms and risk factors are the main determinants of treatment options for patients with essential thrombocythemia. High-risk patients are candidates for cytoreduction, whereas lower-risk patients receive either no treatment, low-dose aspirin, or another antithrombotic therapy. The availability of newer nonleukemogenic and megakaryocyte-specific agents warrants a reassessment of current treatment options.

Immunoglobulin-related amyloidosis presenting as recurrent isolated lymph node involvement.

Up to 37% of cases of generalized primary and secondary amyloidosis demonstrate lymph node involvement. Lymph node involvement as the presenting feature of generalized amyloidosis is uncommon. Isolated lymph node amyloidosis (that is, with no extranodal amyloidosis) is exceedingly rare; review of the literature reveals only two reported cases. A case of recurrent isolated lymph node amyloidosis is presented, with review of the literature.

Myeloproliferative disorders.

Myeloproliferative disorders result from monoclonal proliferation of the pluripotential hematic precursor cell, with preservation of its capacity to differentiate and mature into functional progeny. Phenotypic expression varies with the degree of involvement of each derivative cell type and the extent to which growth is hyperplastic, dysplastic, or malignant. Hyperplastic bone marrow with increased circulating erythrocytes and platelets, reactivation of hematopoiesis in long bones and extramedullary sites, and the development of secondary marrow fibrosis are responsible for complications of thrombosis, hemorrhage, splenic infarction, hypersplenism, and anemia. A predilection for the geriatric population, chronicity, and great variability in phenotypic expression present a challenge in diagnosis and management. Individualized treatment based on thorough understanding of the pathophysiology of myeloproliferative disease is required to maximize complication-free survival by avoiding both the risk of the disease and its therapy and utilizing all available supportive measures in the prevention and treatment of complications.