Tatsuhiko Amenomori

Paroxysmal nocturnal haemoglobinuria clones in patients with myelodysplastic syndromes

Among acquired stem cell disorders, pathological links between myelodysplastic syndromes (MDS) and aplastic anaemia (AA), and paroxysmal nocturnal haemoglobinuria (PNH) and AA, have been often described, whereas the relationship between MDS and PNH is still unclear. We analysed blood cells of patients with MDS to determine the incidence of the PNH clone, and analysed the PIG‐A gene to find mutations characteristic of the PNH clone in MDS. In four (10%) of 40 patients with MDS, flow cytometry showed affected erythrocytes and granulocytes negative for decay‐accelerating factor (DAF) and CD59. The population of affected erythrocytes was smaller in MDS patients with PNH clone (MDS/PNH) than in patients with de novo PNH, and haemolysis was milder in the MDS/PNH patients. PIG‐A mutations were found in granulocytes of all patients with MDS/PNH. In type and site, the PIG‐A mutations were heterogenous, similar to that observed in de novo PNH; i.e. no mutation specific to MDS/PNH was identified. Of note, three of four patients with MDS/PNH each had two PNH clones with different PIG‐A mutations, suggesting that PIG‐A is mutable in patients with MDS/PNH. In a MDS/PNH patient with trisomy 8, FISH detected a distinct karyotype in a portion of granulocytes with PNH phenotype, indicating that PNH and MDS partly shared affected cells. Thus, MDS predisposes to PNH by creating conditions favourable to the genesis of PNH clone. Considering the increasing prevalence and incidence of MDS, these disorders could be useful for investigating the mechanism by which PIG‐A mutation is induced.

Risk of Myelodysplastic Syndromes in People Exposed to Ionizing Radiation: A Retrospective Cohort Study of Nagasaki Atomic Bomb Survivors

PURPOSE The risk of myelodysplastic syndromes (MDS) has not been fully investigated among people exposed to ionizing radiation. We investigate MDS risk and radiation dose-response in Japanese atomic bomb survivors. PATIENTS AND METHODS We conducted a retrospective cohort study by using two databases of Nagasaki atomic bomb survivors: 64,026 people with known exposure distance in the database of Nagasaki University Atomic-Bomb Disease Institute (ABDI) and 22,245 people with estimated radiation dose in the Radiation Effects Research Foundation Life Span Study (LSS). Patients with MDS diagnosed from 1985 to 2004 were identified by record linkage between the cohorts and the Nagasaki Prefecture Cancer Registry. Cox and Poisson regression models were used to estimate relationships between exposure distance or dose and MDS risk. RESULTS There were 151 patients with MDS in the ABDI cohort and 47 patients with MDS in the LSS cohort. MDS rate increased inversely with exposure distance, with an excess relative risk (ERR) decay per km of 1.2 (95% CI, 0.4 to 3.0; P < .001) for ABDI. MDS risk also showed a significant linear response to exposure dose level (P < .001) with an ERR per Gy of 4.3 (95% CI, 1.6 to 9.5; P < .001). After adjustment for sex, attained age, and birth year, the MDS risk was significantly greater in those exposed when young. CONCLUSION A significant linear radiation dose-response for MDS exists in atomic bomb survivors 40 to 60 years after radiation exposure. Clinicians should perform careful long-term follow-up of irradiated people to detect MDS as early as possible.

Dysmegakaryocytopoiesis in acute leukaemias: its predominance in myelomonocytic (M4) leukaemia and implication for poor response to chemotherapy

Megakaryocytopoiesis was morphologically investigated in 129 adults with de novo acute leukaemia. Three types were identified: type I (84 cases), no detectable megakaryocytes; type II (32 cases), quantitatively preserved megakaryocytes with normal morphology; type III (13 cases): quantitatively preserved megakaryocytes but with distinct dysplastic changes such as micromegakaryocytes and megakaryocytes with multiple small separated nuclei. Type III was found in M1 (one out of 21 cases), M2 (one out of 20 cases), M4 (eight out of 24 cases), M6 (two out of four cases) and hypoplastic leukaemia (one out of 13 cases). M3 cases were all classified into type I. Most of acute lymphoid leukaemia cases (21 cases) belonged to type II. Among AML cases, the complete remission (CR) rate by intensive chemotherapy with daunorubicin and cytosine arabinoside was significantly lower in type III (11%) than in types I (87%) and II (71%). Among M4 cases, CR rates in type III (14%) was also significantly lower than those in type I (75%) and II (100%). Thus, the present study indicates the importance of recognizing dysmegakaryocytopoiesis in AML for clariflcation of the heterogeneous biology or pathophysiology of acute leukaemias and formulation of an appropriate therapeutic strategy.

Cytogenetic evidence for partially committed myeloid progenitor cell origin of chronic myelomonocytic leukaemia and juvenile chronic myeloid leukaemia: both granuloctye-macrophage precursors and erythroid precursors carry identical marker chromosome

Summary. We used a micromethod for cytogenetic analysis from single haematopoietic colonies to study two adults with chronic myelomonocytic leukaemia (CMML) and a boy with juvenile chronic myeloid leukaemia (JCML) carrying distinct chromosome abnormalities, 7q—, der(21), and trisomy 21. We wanted to know if both granulocyte‐macrophage (GM) and erythroid precursors are involved in the abnormal clone. In all three patients, their chromosome abnormality was seen in almost all metaphases obtained from GM‐colonies and erythroid bursts. Peripheral blood leucocytes stimulated with phytohaemagglutinin exhibited only normal karyotypes. Clones of B‐cell produced by Epstein‐Barr virus had only normal karyotypes in the CMML patients. These findings indicate that CMML and JCML are clonal haemopathies that originate in a partially committed myeloid progenitor cell.

Progression from myelodysplastic syndrome to acute lymphoblastic leukaemia with Philadelphia chromosome and p190 BCR-ABL transcript

We describe a patient with Philadelphia chromosome (Ph1)‐positive acute lymphoblastic leukaemia (ALL) who developed it 2.5 years after being diagnosed with myelodysplastic syndrome (MDS). The patient initially had refractory anaemia (RA), but progressed to refractory anaemia with excess blasts (RAEB) 2 years later, that terminated in ALL. An immunophenotypic analysis of the lymphoblasts revealed CD10 and CD19 positive cells. The karyotype was normal 46,XY in RA phase, 46,XY,20q– during the RAEB phase, and 46,XY, t(9;22)(q34;q11), 20q– during the ALL phase. Furthermore, p190 BCR‐ABL mRNA was detected in the ALL blasts. These findings indicate that this ALL arose from the MDS clone through multiple cytogenetic evolutions, the final event of which was the acquisition of p190 BCR‐ABL type Ph1

Lymphoid crisis with T-cell phenotypes in a patient with Philadelphia chromosome negative chronic myeloid leukaemia

Summary A case of Philadelphia (Ph1) chromosome negative chronic myeloid leukaemia (CML) developed lymphoid crisis. Immunological marker studies disclosed that the lymphoid cells were sheep erythrocyte‐rosetting‐, Leu‐1+, Leu‐5+, OKT‐4+, OKT‐8+, common ALL antigen‐, HLA‐DR‐, cytoplasmic and surface immunoglobulin‐, MAS 036C(antithymocyte)+ (after in vitro culture) and terminal deoxynucleotidyl transferase‐, indicating T‐cell phenotypes, probably of common thymocytes. Cytochemical staining also demonstrated immature T‐cell characters: dot‐positivity for acid phosphatase and beta‐glucuronidase, and negative for acid alpha‐naphthyl acetate esterase. All bone marrow metaphases exhibited normal karyotypes. Our observation suggests that the neoplastic features of a common stem cell for myeloid and lymphoid cell lines are very similar in Ph1 positive and negative CMLs, and that the stem cell can differentiate towards T‐lineage.

Low-dose cytosine arabinoside regimen induced a complete remission with normal karyotypes in a case with hypoplastic acute myeloid leukaemia with no. 8-trisomy: in vitro and in vivo evidence for normal haematopoietic recovery

Complete remission was achieved in a case of hypoplastic acute myeloid leukaemia with chromosomal abberation of No. 8‐trisomy by giving very low dose of cytosine arabinoside (ara‐C), 10 mg (7.5 mg/m2)/d, by 24 h continuous intravenous infusion for 20 d. We observed a definite cytoreduction phase in the bone marrow (BM) before normal haematopoiesis resumed. The remission BM showed only normal karyotypes in all metaphases examined. Granulocyte/macrophage colonies and erythroid bursts recovered sufficiently in numbers and cytogenetic study on single colonies and bursts revealed only normal karyotypes. These observations provide evidence that a low dose ara‐C regimen can induce remission by cytoreduction which diverts the growth advantage from the leukaemic clone to the normal clones.

Reduced helper (OKT4+): suppressor (OKT8+) T ratios in aplastic anaemia: relation to immunosuppressive therapy

Summary. T cell subset composition of peripheral blood and bone marrow from 22 patients with aplastic anaemia (AA) was studied by monoclonal antibodies (OKT3, OKT4 and OKT8). In the peripheral blood, OKT3 (pan‐T). OKT4 (helper/inducer‐T) and OKT8 (suppressor‐T) cells varied widely in number. The ratios of OKT4:OKT8 exhibited the same tendency. However, a subgroup of AA with a reduced ratio of lower than 1.0 was present both in cases with or without prior prednisolone therapy. Of the eight patients treated with immunosuppressants, four with reduced ratios responded, whereas the other four with normal or higher ratios did not. The ratios of two of the four responders gradually reached the normal level. These results suggest that the reduced OKT4: OKT8 ratio may be related to the cell‐mediated immunosuppressive mechanism postulated as a cause of stem cell inhibition in a subgroup of AA, and indicate prospectively the effectiveness of immunosuppressive therapy.

De novo acute myeloid leukemia in the elderly; a consistent fraction of long-term survivors by standard-dose chemotherapy

To clarify the characteristics of de novo acute myeloid leukemia (AML) among the elderly, we reviewed 112 patients over 60 years old (median age 72 years) who were treated at hospitals in Nagasaki Prefecture with a population of 1.5 million between 1987 and 1994. Reclassification of morphological diagnosis revealed that the proportion of M3 was lower but that of M6 and the incidence of cases with trilineage dysplasia (TLD), known as poor prognostic features, were higher in the elderly than in patients less than 60 years old. Similarly, chromosomal data showed a lower frequency of favorable karyotypes such as t(8;21) and t(15;17) in the elderly. The overall survival of all 112 patients was 10.3% at 5 years. Multivariate analysis indicated that good performance status (PS), low WBC at diagnosis, standard dose multi-drug chemotherapy and all-trans retinoic acid (ATRA) treatment for M3 patients, and morphological findings without TLD were significantly correlated with longer survival. Most of the long-term survivors were found among those who received standard dose therapy in this series, although no consensus has been established how to treat elderly AML patients. We propose that a prospective controlled trial is necessary to confirm the role of standard dose chemotherapy for elderly patients with de novo AML.

Prognostic significance of the morphological dysplastic changes in chronic myelogenous leukemia

Various morphological dysplastic changes were observed in patients with chronic myelogenous leukemia, especially in the acute crisis. To clarify their significance, we divided 45 patients in the acute crisis into two groups by our scoring system, the dysplastic group and the non-dysplastic group. Five of 25 subjects in the non-dysplastic group entered complete remission. None of 20 subjects in the dysplastic group did so, and the mean survival after the onset of acute crisis is significantly shorter in the dysplastic group than in the non-dysplastic group. Some patients in the dysplastic group had obvious dysplastic changes several months before the acute crisis. These findings suggest that acute crises in some cases may occur with or be preceded by the development of dysplastic clones similar to myelodysplastic syndrome; these patients respond poorly to conventional chemotherapy.