Masanao Teramura

Establishment of a human leukaemic cell line (CMK) with megakaryocytic characteristics from a Down's syndrome patient with acute megakaryoblastic leukaemia

Summary. A new megakaryoblastic cell line (CMK), which also exhibits erythroid and myeloid markers, was established from a Downs syndrome patient suffering from acute megakaryoblastic leukaemia. The CMK cells were found to be positive in reactions with anti‐platelet antibodies (anti‐glycoproteins IIb/IIIa and Ib, and Plt‐1). Platelet peroxidase (PPO) reactivity was found to be associated with the nuclear envelope and the endoplasmic reticulum but not with the Golgi apparatus. Some cells possessed cytoplasmic granules with the characteristics of α‐granules and demarcation membranes. Karyotyping revealed near‐tetraploidy (modal chromosome number of 95; ranging 87–98) and a translocation der(17)t(11;17), also found in the original leukaemic cells, confirming that the cells were derived from the patients malignant blasts. The CMK cells were also found to be positive in reaction with anti‐glycophorin A antibody, as well as with anti‐myeloid antibodies (MY4, MY7 and MY9). Treatment of CMK cells with phorbol ester 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) greatly enhanced the reactivity with anti‐platelet antibodies, increased the number of cells in which cytoplasm was dissociated into numerous segments and suppressed the reactivity with anti‐glycophorin A. The proliferation of CMK cells was stimulated by interleukin‐3 (IL‐3) and granulocyte‐macrophage colony stimulation factor (GM‐CSF). This cell line should be a useful tool for analysing the basis of the afferent association between megakaryoblastic leukaemia and Downs syndrome, as well as for further study of megakaryocytic differentiation.

Is eradication therapy useful as the first line of treatment in Helicobacter pylori-positive idiopathic thrombocytopenic purpura? Analysis of 207 eradicated chronic ITP cases in Japan.

A retrospective study was performed to determine the prevalence of Helicobacter pylori (H pylori) infection, the effect of H pylori eradication on platelet counts, and the characteristic clinical features of chronic immune or idiopathic thrombocytopenic purpura (ITP) with H pylori infection. H pylori infection was found in 300 patients, a group that was significantly older (P < .005) and had more cases of hyperplastic megakaryocytes in the bone marrow (P = .01) than patients without H pylori infection.H pylori eradication therapy was performed in 207 H pylori-positive ITP cases, and the platelet count response was observed in 63% of the successful eradication group and in 33% of the unsuccessful eradication group (P < .005). In the successful group, the complete remission and partial remission rates were 23% and 42%, respectively, 12 months after eradication. In the majority of responders, the platelet count response occurred 1 month after eradication therapy, and the increased platelet count continued without ITP treatment for more than 12 months. H pylori eradication therapy was effective even in refractory cases, which were unresponsive to splenectomy. In conclusion, H pylori infection was involved in most ITP patients older than 40 years in Japan, and eradication therapy should be the first line of treatment in H pylori-positive ITP patients.

Cyclosporin A therapy for patients with myelodysplastic syndrome: multicenter pilot studies in Japan

We examined the efficacy of cyclosporin A (CsA) in 50 patients with myelodysplastic syndrome (MDS) consisting from 47 of RA, 1 of RARS, and 2 of RAEB. These patients showed various marrow cell types including hypo-, normo-, and hypercellularity. Patients belonged to the following International Prognostic Scoring System (IPSS) risk groups: 4 of low, 41 of intermediate-1, and 5 of intermediate-2. The median CsA dose was 4.58mg/kg, and treatment responses were classified according to the International Working Group (IWG) criteria. Hematological improvement (HI) was observed in 30 (60%) patients, and all of them were belonged to RA. In the patients with RARS or RAEB, no efficacy was observed. Four (8%) of the responders achieved partial remission (PR) with granulocytes > or = 1500microl(-1), Hb>11g/dl and platelets > or = 100,000microl(-1). Higher response rate (53%) was shown in erythroid lineage (HI-E) compared to platelet (HI-P, 36%) or neutrophil lineage (HI-N, 35%). When we analyzed the correlation between the response to CsA therapy and the karyotype or HLA type, there were significantly more responders with good karyotype or DRB1*1501 than with intermediate/poor karyotypes or with other HLA types. These results indicate the usefulness of CsA therapy for MDS patients with any marrow cellularity, especially for erythroid lineage and patients with good karyotype or DRB1*1501.

Relative increase of granulocytes with a paroxysmal nocturnal haemoglobinuria phenotype in aplastic anaemia patients : the high prevalence at diagnosis

Abstract: To clarify the pathologic significance of granulocytes exhibiting the paroxysmal nocturnal haemoglobinuria (PNH) phenotype in patients with aplastic anaemia (AA), we examined peripheral blood from 100 patients with AA for the presence of granulocytes deficient in glycosylphosphatidylinositol (GPI)‐anchored proteins using a sensitive flow cytometric assay. A significant increase in the frequency of CD55−CD59−CD11b+ granulocytes (>0.003%) compared to normal individuals was observed in 31 of 35 (88.6%) patients with untreated AA at diagnosis. The proportions of patients showing increased PNH granulocytes in treated AA patients with a short (<5 yr) and long (>5 yr) disease duration were 68.6% (11/16) and 20.4% (10/49), respectively. When 19 patients showing increased frequency of PNH granulocytes before therapy were studied 6–12 months after antithymocyte globulin plus cyclosporin A therapy, the frequency decreased to 0.01–90% of pretreatment values in 15 recovering patients. These findings suggest that a relative increase in the number of PNH granulocytes is a common feature of AA at diagnosis, and that it may represent the presence of immunologic pressure to normal haematopoietic stem cells as a cause of AA.

Long-term responses and outcomes following immunosuppressive therapy in large granular lymphocyte leukemia-associated pure red cell aplasia: a Nationwide Cohort Study in Japan for the PRCA Collaborative Study Group

This report describes long-term responses following immunosuppressive therapy in large granular lymphocyte leukemia-associated pure red cell aplasia. Large granular lymphocyte leukemia-associated pure red cell aplasia accounts for a significant portion of secondary pure red cell aplasia cases. However, because of its rarity, long-term responses and relapse rates after immunosuppressive therapy are largely unknown. We conducted a nationwide survey in Japan and collected 185 evaluable patients. Fourteen patients with large granular lymphocyte leukemia-associated pure red cell aplasia were evaluated. Cyclophosphamide, cyclosporine A and prednisolone produced remissions in 6/8, 1/4 and 0/2 patients respectively. Seven and 5 patients were maintained on cyclophosphamide or cyclosporine A respectively. Two patients relapsed after stopping cyclophosphamide, and 2 patients relapsed during maintenance therapy with cyclosporine A. The median relapse-free survival in the cyclophosphamide - and the cyclosporine A groups was 53 and 123 months respectively. Large granular lymphocyte leukemia-associated pure red cell aplasia showed a good response to either cyclophosphamide or cyclosporine A. Most patients continued to receive maintenance therapy and it remains uncertain whether cyclophosphamide or cyclosporine A can induce a maintenance-free hematologic response in large granular lymphocyte leukemia-associated pure red cell aplasia.

Circulating megakaryocyte progenitors in myeloproliferative disorders are hypersensitive to interleukin-3

Summary. Previous studies have reported that megakaryocyte progenitors in myeloproliferative disorders (MPD) formed spontaneous megakaryocyte colonies without the addition of megakaryocyte colony‐stimulating factor (Meg‐CSF). To determine whether this spontaneous colony formation is due to autocrine proliferation of MPD megakaryocyte progenitors or to hypersensitivity to Meg‐CSF that might exist in the culture system, we investigated colony‐forming unit‐megakaryocytes (CFU‐Meg) in the peripheral blood of 11 MPD patients, using serum‐free cultures. Spontaneous megakaryocyte colonies were observed in serum‐free cultures of nonadherent mononuclear cells (NAdMNC) obtained from MPD patients with thrombocytosis, whereas the NAdMNC of MPD patients without thrombocytosis, that of patients with reactive thrombocytosis and normal subjects never formed spontaneous colonies. However, the spontaneous colonies from MPD patients with thrombocytosis disappeared in cultures using highly purified CD34‐positive cells as target cells.

Mutations of the p53 tumour suppressor gene in haematologic neoplasms

Mutations of the p53 tumour suppressor gene have frequently been observed in several types of solid tumours and are believed to be implicated in the development of these tumours. To determine the relevance of p53 mutations in haematologic neoplasms, we performed polymerase chain reaction‐single strand conformation polymorphism analysis on the p53 gene in 45 patients with various types of haematologic neoplasms. In exons 5–8 containing highly conserved regions, mobility shifts indicating sequence alterations were detected in four of the 45 patients, and subsequent sequencing was performed. A point mutation resulting in a novel stop codon was detected at codon 213 in one of 23 cases of chronic myelogenous leukaemia (one of five cases of blast crisis). Point mutations causing amino acid substitutions were detected in one of four cases of myelodysplastic syndrome at codon 195, one of three cases of adult T‐cell leukaemia at codon 281, and one of eight cases of acute lymphoblastic leukaemia at codon 281, and these missense mutations were accompanied by loss of the wild type allele. Patients harbouring these nonsense and missense mutations were in advanced disease stages. These findings suggest that mutational inactivation of the p53 gene is infrequent but is involved in the tumorigenesis of several types of haematologic neoplasms at least in some cases.

Effect of interleukin 11 on normal and pathological thrombopoiesis.

Abstract Interleukin 11 (IL-11) is a stromal cell-derived cytokine that has multiple effects on hematopoietic and nonhematopoietic systems. In vitro, it enhances the growth of early progenitors and promotes megakaryocytopoiesis and erythropoiesis. In healthy animals, IL-11 administration stimulates megakaryocyte maturation and increases peripheral platelet counts. IL-11 accelerates the recovery of peripheral neutrophil, erythrocyte, and platelet counts in mice that have undergone cytoablative treatment. Therefore, IL-11 may be useful clinically as an agent promoting recovery from hematopoiesis. However, its clinical use in patients with hematological malignancies may be restricted because IL-11 has been reported to stimulate some leukemia and myeloma cells. In the United States, phase I trials have shown that IL-11 accelerates recovery from chemotherapy-induced or bone-marrow transplantation (BMT)-induced thrombocytopenia. In Japan, phase II trials studying the thrombopoietic effect of IL-11 in patients with solid tumors postchemotherapy, in patients undergoing BMT, and in patients with aplastic or refractory anemia are now under way. Recently, thrombopoietin (TPO) has been cloned, and its thrombopoietic effect and accelerating effect on platelet count recovery in thrombopoietic states have been demonstrated in animal models. The physiological effect of TPO is restricted to hematopoiesis; therefore, it may have fewer side effects than IL-11. However, in addition to its hematopoietic effect, IL-11 administration to mice that have undergone cytoablative therapy significantly decreases morbidity and mortality due to chemotherapy-related endogenous infections caused by gut microorganisms. Therefore, IL-11 can be used in patients postchemotherapy and post-BMT not only to promote platelet recovery but also to prevent life-threatening infections. The use of in-vitro-expanded hematopoietic stem cells for BMT or as target cells for gene therapy is one of the most exciting areas in the field of medicine. Since IL-11 can expand hematopoietic progenitor-cell populations when used in combination with other cytokines, it may be useful as an ex vivo hematopoietic progenitor-cell-amplifying agent

Mechanism of action of antithymocyte globulin in the treatment of aplastic anaemia: in vitro evidence for the presence of immunosuppressive mechanism.

Antithymocyte globulin (ATG) is one of the effective drugs used in the treatment of aplastic anaemia (AA). Although it has been speculated that the mechanism of action of ATG is mediated by its immunosuppressive effect on lymphocytes which might have an inhibitory effect on haemopoietic stem and progenitor cells, no definite evidence of the presence of such a mechanism has been demonstrated. In this study we investigated whether such a mechanism is truly operating in ATG therapy for AA. In five patients who responded to ATG, bone marrow cells were obtained after haematological recovery and CD34‐positive cells were separated by immunobeads. Autologous CD34‐positive cells were mixed with autologous peripheral CD4‐ or CD8‐positive cells obtained before ATG therapy and after haematological recovery, liquid‐cultured for 12 h, and then cultured in methylcellulose for 14 d in the presence of haemopoietic growth factors. In all five cases studied, only the CD8 cells obtained before ATG therapy suppressed the colony forming unit‐granulocyte‐macrophage (CFU‐GM)‐ and burst forming unit‐erythroid (BFU‐E)‐derived colony formation. This result is definite evidence that one of the mechanisms of action of ATG in AA is an inhibitory effect on CD8‐positive cells which have suppressive activity for the growth of haemopoietic progenitor cells.

L265P Mutation of the MYD88 Gene Is Frequent in Waldenström’s Macroglobulinemia and Its Absence in Myeloma

L265P mutation in the MYD88 gene has recently been reported in Waldenström’s macroglobulinemia; however the incidence has been different according to the methods used. To determine the relevance and compare the incidence by different methods, we analyzed the L265P mutation in bone marrow mononuclear cells from lymphoid neoplasms. We first performed cloning and sequencing in 10 patients: 8 Waldenström’s macroglobulinemia; 1 non-IgM-secreting lymphoplasmacytic lymphoma; and 1 low grade B-cell lymphoma with monoclonal IgG protein. The L265P mutation was detected in only 1/8 Waldenström’s macroglobulinemia patients (2 of 9 clones). To confirm these results, direct sequencing was performed in the 10 patients and an additional 17 Waldenström’s macroglobulinemia patients and 1 lymphoplasmacytic lymphoma patient. Nine of 28 patients (7/25 Waldenström’s macroglobulinemia, 1/2 lymphoplasmacytic lymphoma, and B-cell lymphoma) harbored the mutation. We next tested for the mutation with BSiE1 digestion and allele-specific polymerase chain reaction in the 28 patients and 38 patients with myeloma. Aberrant bands corresponding to the mutation were detected by BSiE1 digestion in 19/25 patients with Waldenström’s macroglobulinemia (76%), 1/2 lymphoplasmacytic lymphoma and B-cell lymphoma, but not in the 38 myeloma patients. The L265P mutation was more frequent in patients with Waldenström’s macroglobulinemia than in those with myeloma (p=1.3x10-10). The mutation was detected by allele-specific polymerase chain reaction in 18/25 Waldenström’s macroglobulinemia patients (72%). In the 25 Waldenström’s macroglobulinemia patients, the L265P was more frequently detected by BSiE1 digestion than by direct sequencing (p=5.3x10-4), and in males (15/16, 94%) than in females (4/9, 44%) (p=1.2x10-2). No siginificant difference was observed in the incidence of the L265P mutation between BSiE1 digestion and allele-specific polymerase chain reaction (p=0.32). These results suggest that the L265P mutation is involved in the majority of Waldenström’s macroglobulinemia. BSiE1 digestion and allele-specific polymerase chain reaction may detect a small fraction of mutated cells in some cases.