Flow cytometric analysis of megakaryocyte ploidy in chronic myeloproliferative disorders and reactive thrombocytosis

Abstract: Megakaryocyte (MK) ploidy patterns were analysed by flow cytometry in 29 newly diagnosed and previously untreated patients with chronic myeloproliferative disorders (MPD) and concomitant thrombocytosis, in 9 patients with reactive thrombocytosis (RT) and in 12 healthy individuals. Unfractionated bone marrow from routine aspirates was used. MKs were identified with a fluorescein labelled monoclonal antibody specific for glycoprotein IIIa (GPIIIa) and DNA was stained with propidium iodide. For the 12 healthy volunteers the mean modal ploidy number was 16 N; the 9 patients with RT displayed an identical MK ploidy pattern. The frequency of MKs with a ploidy ≥32 N was 45% among the patients with essential thrombocythaemia (ET) compared to 32% among the healthy volunteers (p < 0.001). MKs with ploidy number ≥ 64 N, comprising approximately 13% of the total number of MKs, was a characteristic finding in the patients with ET. Similar findings were present in 8 patients with polycythaemia vera (PV). In patients with PV 34% and 6% of the MKs displayed ploidies ≥32 N and ≥64 N, respectively. In contrast, a distinct shift towards lower ploidy number, with 63% of MKs ≤ 8 N, was found among the 4 patients with chronic myeloid leukaemia (CML). The present results indicate that by using flow cytometric analysis of MK ploidy distribution in patients with thrombocytosis, those with a reactive cause are likely to be discriminated from patients with myeloproliferative thrombocytosis, i.e. PV and ET on one hand and CML on the other hand. The distinction between ET and PV, however, has to be made on other grounds.     

Interferon alpha-2b as treatment for Philadelphia-negative chronic myeloproliferative disorders with excessive thrombocytosis

Summary. We treated 32 patients with Ph¹-negative chronic myeloproliferative disorders (CMD) with excessive thrombocytosis with Interferon α-2b (IFN α-2b): 26 had essential thrombocythaemia, ET (18 previously untreated, eight pretreated); one thrombocythaemia after treatment for Hodgkin's disease (HD); two thrombocythaemia associated with non-Hodgkin's lymphoma (NHL); three stage II idiopathic myelofibrosis (IM). IFN was given at daily doses of 1−4 × 10⁶ IU. Twenty-seven patients (84%) responded, 17 (53%) achieved complete haematologic response after a median time of 12 weeks, and 10 (31%) partial haematologic response. Median platelet levels declined in complete haematologic response patients from 1190 to 335 × 10⁹/I. Normalization of megakaryocyte (MK) levels was observed in 8/17 complete haematologic response patients treated for 9–12 months, with decreased bone marrow (BM) cellularity. Side effects requiring dose reduction or discontinuation of treatment occurred in 28% of cases with IFN doses of 2 or 4 × 10⁶ IU. After 1 year of continuous IFN treatment, responses were maintained with conventional chemotherapy or low-dose IFN. This study demonstrates that IFN has definite therapeutic activity in CMD with excessive thrombocytosis. This biological agent, either alone or in combination with other antineoplastic treatment, may represent a new therapeutic approach for these disorders.     

Treatment of thrombocytosis in myeloproliferative disorders with interferon alpha-2a

Summary In an open prospective pilot trial, we tested the effect of recombinant interferon alpha-2a (rIFN alpha-2a) on thrombocytosis in myeloproliferative disorders (MPD). Since October 1986, 13 patients with MPD (4 with chronic granulocytic leukemia, 4 with polycythemia vera, 3 with essential thrombocythemia and 2 with myeloid metaplasia) were treated with rIFN alpha-2a. Platelet counts decreased in all treated patients within 2 to 10 weeks from a median value of 1,050×10⁹/l (range 610–1,940×10⁹/l) to 340×10⁹/l (range 230–495×10⁹/l). The response was dose-dependent. In 11 patients we observed a simultaneous reduction of the white blood cell count. Six patients still continue the IFN alpha-2a therapy. In 7 treatment was discontinued, because of chronic side effects in 3, and because of noncompliance in one. In these patients, thrombocytosis recurred after discontinuation of the therapy. These results show that rIFN alpha-2a is effective in controlling thrombocytosis in MPD. However, the long-term benefit of interferon in these disorders remains to be established.     

Platelet membrane glycoprotein abnormalities in patients with myeloproliferative disorders and secondary thrombocytosis

Carbohydrate-specific surface labelling and 125I-labelled lectin binding techniques, in combination with one- or two-dimensional (non-reduced/reduced) SDS-polyacrylamide gel electrophoresis have been used with platelets from patients with myeloproliferation disorders and secondary thrombocytosis and from healthy donors. In essential thrombocythaemia platelet membrane glycoproteins were significantly less sialylated than in normals (particularly GP Ib and IIIa). Increased binding of 125I-labelled Lens culinaris lectin to thrombospondin and GP IIIa indicated a defect in the glucose/mannose glycosylation of the platelet glycoproteins in essential thrombocythaemia. In polycythaemia vera and in chronic myeloid leukaemia the terminal sialic acid of glycoprotein IIIb was labelled slightly more than normal. In chronic myeloid leukaemia there was increased labelling of the penultimate galactose/N-acetylgalactosamine residues of GP Ib, IIb, IIIa and IIIb. In comparison to myeloproliferative disorders, platelets from patients with secondary thrombocytosis showed no significant changes, except for platelets from two patients with idiopathic thrombocytopenic purpura which showed an increased sialylation of all surface glycoproteins.     

Monoclonal gammopathy in chronic myeloproliferative disorders

Summary The incidence of monoclonal gammopathy in 61 patients with chronic myeloproliferative disorders (CMPD) was studied. The distribution of patients among the CMPD subgroups was: chronic myelocytic leukemia, 24 patients; myelofibrosis, 11; polycythemia vera, 15; essential thrombocythemia, 7; unclassified MPD, 4 patients. Monoclonal gammopathy was found in 5 patients (8.2%). Two of these patients (1 IgA/k and 1 IgM/k) had myelofibrosis and 3 (2 IgG/k and 1 IgG/) polycythemia vera.The presence of monoclonal gammopathy indicates an involvement of the lymphoplasmatic system in CMPD.     

Cytogenetic studies in chronic myeloproliferative disorders

Cytogenetic studies were performed on 113 patients with the clinical diagnosis of a chronic myeloproliferative disorder: 70 were classified as chronic myelocytic leukemia (CML), 8 as polycythemia vera (PV), 10 as osteomyelofibrosis/sclerosis (OMS), and 15 as unclassified myeloproliferative disorder (UMPD). 2 patients, 1 with UMPD and 1 with subacute leukemia, were reclassified as CML after the cytogenetic study. In the group comprising PV, OMS, and UMPD, 28% (9/32) had a chromosomally abnormal clone. The chromosomes affected involved those reported to show nonrandom alterations in myeloproliferative disorders, namely the chromosomes, 1, 7, 8, and 9.4 patients exhibited a loss of the Y-chromosome.     

Unexplained pulmonary hypertension in chronic myeloproliferative disorders

AIM: To investigate the potential association between the chronic myeloid disorders (CMDs), including the chronic myeloproliferative disorders, and pulmonary hypertension (PH). METHODS: Retrospective chart review of patients who had received diagnoses of both CMD and PH. Patients with a known cause of PH were excluded. The diagnosis of a CMD was based on established criteria. The diagnosis of PH was based on echocardiographic data or right heart catheterization data. RESULTS: Twenty-six patients satisfied the criteria for both a CMD and PH. Twelve patients had myeloid metaplasia with myelofibrosis (MMM), 5 patients had essential thrombocythemia (ET), 6 patients had polycythemia vera, 2 patients had a myelodysplastic syndrome, and 1 patient had chronic myeloid leukemia. Twenty-two patients (92%) received treatment for their CMDs, which included therapy with hydroxyurea (18 patients), anagrelide (7 patients), and busulfan (3 patients). PH was diagnosed a median of 8 years after recognition of the CMD (range, 0 to 26 years). The median right ventricular systolic pressure (RVsys) was 71 mm Hg (range, 32 to 105 mm Hg). RVsys correlated with the platelet count in patients with MMM (r = 0.30) and ET (r = 0.6) and with the hemoglobin levels in patients with PV (r = 0.77). Treatment of CMD did not seem to affect the severity of the pulmonary artery pressures as measured by serial echocardiography. With a median survival time of 18 months after the diagnosis of PH, the cause of death in the majority of the patients was cardiopulmonary. CONCLUSIONS: The current study suggests a higher than expected incidence of PH in patients with MMM, PV, and ET. Prognosis in such a setting is poor and may not be influenced by aggressive treatment of the underlying hematologic disorder.     

Interferon-alpha-induced morphological changes of megakaryocytes: a histomorphometrical study on bone marrow biopsies in chronic myeloproliferative disorders with excessive thrombocytosis

Interferon(rIFN)-alpha, a successful therapeutic agent in the control of thrombocytosis, has been shown to suppress human megakaryopoiesis. We investigated bone marrow biopsies from 12 patients with thrombocytosis due to chronic myeloproliferative disorders. Prior to treatment as well as during rIFN-alpha-2c therapy, several morphometric parameters of megakaryopoiesis were evaluated. Megakaryocyte density decreased significantly in all patients, megakaryocyte size decreased in polycythaemia vera, agnogenic myeloid metaplasia, and essential thrombocythaemia, but increased in chronic myeloid leukaemia. The various changes observed during therapy indicate an inhibitory effect of rIFN-alpha-2c on megakaryopoiesis and suggest a selective influence on megakaryocytes at various stages of maturation. Increased numbers of pyknotic (bare) nuclei may reflect a shortening of megakaryocyte life-span. No remarkable changes were found in the fibre content of the bone marrow.     

Heterogeneity of clonal development in chronic myeloproliferative disorders

Recent reports have suggested a previously unexpected variability in the expression of the dominant neoplastic clone in myeloproliferative disorders (MPD). We evaluated 49 female patients with MPD and informative at the X-linked androgen receptor (AR) locus to establish the X chromosome inactivation pattern of hemopoietic cells. Whereas in chronic myelogenous leukemia (CML) the granulocytes (PMN) were uniformly of monoclonal origin, a striking heterogeneity of clonal development was found in PMN from patients with other MPD, with up to 50% of them expressing a polyclonal pattern of X inactivation. Am. J. Hematol. 60:158–160, 1999. © 1999 Wiley-Liss, Inc.     

Serum procollagen III peptide in chronic myeloproliferative disorders

Using a radioimmunoassay the serum concentration of the N-terminal propeptide of type III procollagen (P-III-P) was measured in 35 patients with chronic myeloproliferative disorders, including idiopathic myelofibrosis (n = 10), osteomyelosclerosis (n = 4), transitional myeloproliferative disorder (n = 5), polycythaemia vera (n = 10) and chronic myelogenous leukaemia (n = 6). The normal range in 35 healthy controls was 4.9-11.7 ng/ml. The serum concentration of P-III-P increased with increasing degrees of bone marrow reticulin fibrosis. By contrast, almost normal levels were detected in osteomyelosclerosis with an indolent clinical course, in which an excessive deposition of mature collagen fibres was found, representing mainly type I collagen. These observations indicate that the serum P-III-P level is positively correlated to the degree of bone marrow reticulin fibrosis, whereas levels are near normal in patients with osteomyelosclerosis and stable disease. Measurement of serum P-III-P may be a useful indicator of disease activity in myelofibrosing conditions.     

Thrombocythaemic erythromelalgia in chronic myeloproliferative and myelodysplastic disorders

Erythromelalgia, which is specific for primary thrombocythaemia or polycythaemia with thrombocythaemia, is reported in a case of primary myelofibrosis at platelet counts of between 350 and 450 X 10(9)/l. In addition, the unexpected occurrence of thrombocythaemic erythromelalgia associated with Ph1 chromosome positive micromegakaryocytic myelofibrosis and with myelodysplastic syndrome type II is described. Therefore it is concluded that erythromelalgia may occur in all variants of myeloproliferative disease as well as myelodysplastic syndrome as long as they present with thrombocythaemia.     

Reticulated platelets are increased in chronic myeloproliferative disorders, pure erythrocytosis, reactive thrombocytosis and prior to hematopoietic reconstitution after intensive chemotherapy

Reticulated platelets with a high RNA content represent the most recently released platelets and are regarded to reflect thrombopoiesis. In the present study we used flow cytometric analysis to determine the percentage of reticulated platelets in peripheral blood for patients with chronic myeloproliferative disorders (polycythemia vera, essential thrombocytosis) and acute myelogenous leukemia (AML) patients with severe chemotherapy-induced thrombocytopenia. Patients with essential thrombocytosis and polycythemia vera showed increased levels of reticulated platelets compared with healthy controls, and these levels persisted after normalization of the platelet count by hydroxyurea or interferon-alpha treatment. Patients with reactive thrombocytosis or thrombocytopenia with increased platelet turnover often had higher levels of circulating reticulated platelets than patients with myeloproliferative disorders. Furthermore, AML patients with severe chemotherapy-induced cytopenia showed low levels that started to increase 1-9 days prior to hematopoietic reconstitution. To summarize and conclude: (i) circulating reticulated platelets are increased in patients with chronic myeloproliferative disorders, reactive thrombocytosis and thrombocytopenia due to increased platelet turnover; (ii) patients with pure erythrocytosis often have additional abnormalities in the thrombopoiesis; and (iii) the levels of reticulated platelets seem to predict hematopoietic reconstitution for patients receiving intensive AML therapy.     

Management of Philadelphia negative chronic myeloproliferative disorders in pregnancy

The management of pregnancy in Philadelphia negative chronic myeloproliferative disorders (CMPDs) is an increasingly frequent problem. In the literature, most pregnancies are reported for women with essential thrombocythemia (ET) with about 400 pregnancies in about 200 women. In ET, first trimester abortion is the most frequent complication occurring in about one third of pregnancies. Interestingly, the incidence of maternal complications is relatively low with 3% for major thromboembolic and 2% for major bleeding events. The presence of the Jak2 mutation seems to be an independent predictor of pregnancy complications. Pregnancies in ET should be stratified according to underlying risk factors in low, high and highest risk pregnancies. Women with low risk pregnancies are treated with low-dose aspirin, whereas women with high and higher risk pregnancies may benefit from low-dose aspirin plus interferon alpha +/- low molecular weight heparin throughout pregnancy and at least for six weeks post-partum. In polycythemia vera (PV) there is only very few information on pregnancy outcome with 36 pregnancies reported in the literature. According to these data pregnancy in PV is per se a high risk situation. Accordingly, all women with PV should be treated with low-dose aspirin. Some pregnant PV patients may benefit from a more intensive therapy including interferon alpha +/- low molecular weight heparin throughout pregnancy and at least for six weeks post-partum.