Quantification of adult T-cell leukemia/lymphoma cells using simple four-color flow cytometry.

BACKGROUND: The absolute number of adult T-cell leukemia/lymphoma (ATL) cells in peripheral blood is an essential indicator to evaluate disease status. However, microscopically counting ATL cells based on morphology requires experience and tends to be inaccurate due to the rarity of ATL. METHODS: Based on our research showing that acute-type ATL cells are specifically enriched in the CD4+/CD7- (CD7N) fraction, a new analytical method to accurately quantify ATL cells was established using an internal bead standard and simple four-color flow cytometry. This method was verified by comparison with microscopic examination of 49 peripheral blood samples and used to follow up patients. RESULTS: A strong correlation was observed between the number of CD7N cells measured by flow cytometry and the number of abnormal lymphocytes measured microscopically by experienced technicians [Pearson's R, 0.963; Spearman's rho, 0.921; intercorrelation coefficient, 0.962]. The linear regression coefficient was close to 1 (ß=1.013). Our method could detect 1 cell/µL, and the limit of quantitation was between 2.9 and 9.8 cells/µL. The frequency of CD7N cells among CD4+ cells changed during chemotherapy, which reflected differences between chemosensitive and chemoresistant cases. Kaplan-Meier analysis with a log-rank test showed that patients with decreased CD7N proportion after chemotherapy had significantly longer disease-specific survival (p=0.003). CONCLUSIONS: Our newly established method quantified tumor cells in patients with acute-type ATL. Furthermore, this method was useful for assessing the efficacy of chemotherapy, and the change of the CD7N proportion could be more important to predict prognosis.

Clinical characteristics of 15 children with juvenile myelomonocytic leukaemia who developed blast crisis: MDS Committee of Japanese Society of Paediatric Haematology/Oncology.

Juvenile myelomonocytic leukaemia (JMML) is a rare haematopoietic stem cell disease of early childhood, which can progress to blast crisis in some children. A total of 153 children diagnosed with JMML were reported to the Myelodysplastic Syndrome Committee in Japan between 1989 and 2007; 15 of them (9·8%) had 20% or more blasts in the bone marrow (blast crisis) during the disease course. Blast crisis occurred during observation without therapy (n = 3) or with oral 6-mercaptopurine treatment (n = 9) and in relapse after haematopoietic stem cell transplantation (HSCT; n = 3). Six patients had a complex karyotype (5 including monosomy 7) and an additional three patients had isolated monosomy 7 at blast crisis. Seven patients received HSCT after blast crisis and four of them achieved remission. Eleven out of the 15 patients died; the cause of death was disease progression in 10 patients and transplant-related complication in one patient. In summary, patients with blast crisis have poor prognosis and can be cured only by HSCT. The emergence of monosomy 7 and complex karyotype may be characteristic of blast crisis in a substantial subset of children.

Clinical characteristics and treatment outcome in 65 cases with refractory cytopenia of childhood defined according to the WHO 2008 classification.

This study analysed 65 children who were prospectively registered between 1999 and 2008 and fulfilled the World Health Organization 2008 criteria of refractory cytopenia of childhood (RCC). First-line therapy was determined by the treating physicians: 25 patients received immunosuppressive therapy (IST), 12 patients received haematopoietic stem cell transplantation (HSCT) and one patient received intensive chemotherapy. The remaining 27 patients were followed without treatment for more than 2 years (watch and wait; WW). In the WW group, 18 patients had stable disease without further intervention. Thirteen of 29 patients (45%) who ended up receiving IST showed response. The combination of ciclosporin and antithymocyte globulin was not shown to be superior to ciclosporin alone with regard to response rate or survival. Of 28 patients who ended up undergoing HSCT, 17 patients are alive in complete remission, whereas nine patients died mostly due to transplantation-related mortality. The 5-year overall survival for all patients was 82 ± 5%. Eight patients suffered from disease progression. Patients with monosomy 7 or multilineage-dysplasia had a significantly higher incidence of disease progression. This analysis revealed heterogeneity in the clinical course of RCC, varying from those who remained stable for long periods to those who progressed to advanced disease.

Leukemic T cells are specifically enriched in a unique CD3(dim) CD7(low) subpopulation of CD4(+) T cells in acute-type adult T-cell leukemia.

The morphological discrimination of leukemic from non-leukemic T cells is often difficult in adult T-cell leukemia (ATL) as ATL cells show morphological diversity, with the exception of typical "flower cells." Because defects in the expression of CD3 as well as CD7 are common in ATL cells, we applied multi-color flow cytometry to detect a putative leukemia-specific cell population in the peripheral blood from ATL patients. CD4(+) CD14(-) cells subjected to two-color analysis based on a CD3 vs CD7 plot clearly demonstrated the presence of a CD3(dim) CD7(low) subpopulation in each of nine patients with acute-type ATL. The majority of sorted cells from this fraction showed a flower cell-like morphology and carried a high proviral load for the human T-cell leukemia virus type 1 (HTLV-I). Genomic integration site analysis (inverse long-range PCR) and analysis of the T cell receptor Vß repertoire by flow cytometry indicated that the majority of leukemia cells were included in the CD3(dim) CD7(low) subpopulation. These results suggest that leukemic T cells are specifically enriched in a unique CD3(dim) CD7(low) subpopulation of CD4(+) T cells in acute-type ATL.

Generation of functional erythrocytes from human embryonic stem cell-derived definitive hematopoiesis.

A critical issue for clinical utilization of human ES cells (hESCs) is whether they can generate terminally mature progenies with normal function. We recently developed a method for efficient production of hematopoietic progenitors from hESCs by coculture with murine fetal liver-derived stromal cells. Large numbers of hESCs-derived erythroid progenitors generated by the coculture enabled us to analyze the development of erythropoiesis at a clone level and investigate their function. The results showed that the globin expression in the erythroid cells in individual clones changed in a time-dependent manner. In particular, embryonic epsilon-globin-expressing erythroid cells from individual clones decreased, whereas adult-type beta-globin-expressing cells increased to approximately 100% in all clones we examined, indicating that the cells undergo definitive hematopoiesis. Enucleated erythrocytes also appeared among the clonal progeny. A comparison analysis showed that hESC-derived erythroid cells took a similar differentiation pathway to human cord blood CD34(+) progenitor-derived cells when examined for the expression of glycophorin A, CD71 and CD81. Furthermore, these hESC-derived erythroid cells could function as oxygen carriers and had a sufficient glucose-6-phosphate dehydrogenase activity. The present study should provide an experimental model for exploring early development of human erythropoiesis and hemoglobin switching and may help in the discovery of drugs for hereditary diseases in erythrocyte development.

[Prognosis of 75 patients with juvenile myelomonocytic leukemia: prospective study by MDS committee in the Japanese Society of Pediatric Hematology].

Juvenile myelomonocytic leukemia (JMML) is a myelodysplastic/myeloproliferative disorder of young children. Because the disease is rare and the diagnosis is difficult, a prospective registration of patients suspected of having JMML with a pathological central review have been conducted by the MDS Committee of the Japanese Society of Pediatric Hematology. Between 1999 and 2006, 75 children with JMML were enrolled and diagnosed through this system. Median age at diagnosis was 20 months (1∼85 months). Cytogenetic abnormalities were detected in 21 patients, including 11 with monosomy 7. The 5-year overall survival (OS) was 60%. Regarding the treatment, 61 of the 75 patients received stem cell transplantation (SCT). Conditioning regimen varied widely, and the source of grafts was bone marrow for 43 patients, peripheral blood for 5, and cord blood for 13. The 5-year OS after SCT was 61%. Notably, patients who received cord blood transplantation had inferior survival than those who received grafts from other sources (38 vs. 68%; P=0.03). Given better recognition of the disease, a multi-center protocol study on SCT, JMML11, is now being planned by the Japanese Pediatric Leukemia/Lymphoma Study Group.

Novel method for efficient production of multipotential hematopoietic progenitors from human embryonic stem cells.

We propose a novel method for the efficient production of hematopoietic progenitors from human embryonic stem cells (hESC) via coculture with murine fetal liver-derived stromal cells, in which embryonic hematopoiesis dramatically expands at midgestation. We generated various hematopoietic progenitors in coculture, and this hematopoietic activity was concentrated in cobblestone-like cells derived from differentiated hESC. The cobblestone-like cells mostly expressed CD34 and retained an endothelial cell potential. They also contained hematopoietic colony-forming cells, especially erythroid and multilineage colony-forming cells at high frequency. The multipotential hematopoietic progenitors abundant among the cobblestone-like cells produced almost all types of mature blood cells, including adult-type alpha-globin-expressing erythrocytes and tryptase/chymase double-positive mast cells. These progenitors showed neither the immature properties of ESC nor the potential to differentiate into endoderm and ectoderm at a clonal level. The coculture system developed for hESC can provide a novel source of hematopoietic and blood cells for applications in cellular therapy and drug screening.

Validation of the revised International Prognostic Scoring System in patients with myelodysplastic syndrome in Japan: results from a prospective multicenter registry.

The Japanese National Research Group on Idiopathic Bone Marrow Failure Syndromes has been conducting prospective registration, central review, and follow-up study for patients with aplastic anemia and myelodysplastic syndrome (MDS) since 2006. Using this database, we retrospectively analyzed the prognosis of patients with MDS. As of May 2016, 351 cases were registered in this database, 186 of which were eligible for the present study. Kaplan-Meier analysis showed that overall survival (OS) curves of the five risk categories stipulated by the revised international prognostic scoring system (IPSS-R) were reasonably separated. 2-year OS rates for the very low-, low-, intermediate-, high-, and very high-risk categories were 95, 89, 79, 35, and 12%, respectively. In the same categories, incidence of leukemic transformation at 2 years was 0, 10, 8, 56, and 40%, respectively. Multivariate analysis revealed that male sex, low platelet counts, increased blast percentage (>2%), and high-risk karyotype abnormalities were independent risk factors for poor OS. Based on these data, we classified Japanese MDS patients who were classified as intermediate-risk in IPSS-R, into the lower risk MDS category, highlighting the need for careful assessment of treatments within low- and high-risk treatment protocols.

Clinicopathological characteristics of erythroblast-rich RAEB and AML M6a in children.

The distinction between RAEB, RAEB-T and AML M6a is difficult when erythroblasts in the bone marrow (BM) exceed 50%. We analyzed 19 children (2 RAEB, 13 RAEB-T and 4 AML M6a) enrolled in a prospective pathological central review in Japan and divided them into two groups according to the myeloblasts percentage among non-erythroid cells in BM: group A (n = 8), 5-19% myeloblasts; group B (n = 11), 20% or more myeloblasts. Their characteristics were very similar except for the number of myeloblasts. The median WBC was in the range of 1.0-5.0 x 10(9) L(-1), the median Hb was around 7.5 g/dL, the median MCV was greater than 90 fL and both group had Auer rods at 60-65%. Severe multilineage dysplasia was observed in most of the patients in two groups. Six with group A and seven with group B treated with AML type chemotherapy achieved complete remission. Five with group A and seven with group B undergoing SCT are alive at a median of 3 years after diagnosis. Erythroblast-rich RAEB and AML M6a in children have similar characteristics and may belong to a single disease entity.

RAS-blocking bisphosphonate zoledronic acid inhibits the abnormal proliferation and differentiation of juvenile myelomonocytic leukemia cells in vitro.

Juvenile myelomonocytic leukemia (JMML) is a clonal myeloproliferative/myelodysplastic disorder of early childhood with a poor prognosis. JMML cells are characterized by hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF) caused by a continuously activated GM-CSF receptor-retrovirus-associated sequence (RAS) signal transduction pathway through various molecular mechanisms, resulting in spontaneous GM colony formation in vitro. Bisphosphonate zoledronic acid (ZOL), a RAS-blocking compound, suppressed colony formation from bone marrow (BM) cells of 8 patients with JMML and 5 healthy control subjects without and with GM-CSF (10 ng/mL), respectively, in a dose-dependent manner in clonal culture. At 10 microM ZOL, however, spontaneous GM colony formation from JMML BM cells decreased to 3%, but the formation of G colonies containing granulocytes, but no macrophages, was enhanced, whereas 40% of GM colonies were retained and G colony formation was not affected in culture of normal BM cells with GM-CSF. In suspension culture, cytochemical and flow cytometric analyses showed that 10 microM ZOL also inhibited spontaneous proliferation and differentiation along monocyte/macrophage lineage of JMML BM cells but not the development of normal BM cells by GM-CSF. The inhibitory effect of ZOL on JMML cells was confirmed at a single-clone level and observed even at 3 microM. The current result offers a novel approach to therapy in JMML.