Nobuo Oguma

Decreased L-selectin expression in CD34-positive cells from patients with chronic myelocytic leukaemia

Abnormal adhesive interaction between bone marrow stroma and progenitors, one of the causes of unregulated proliferation in chronic myelocytic leukaemia (CML), may be caused by some alterations in adhesion molecules on CML progenitors. We investigated the expression of adhesion molecules (CD44, VLA‐5, VLA‐4, LFA‐1, ICAM‐1, L‐selectin and c‐kit) on bone marrow CD34++ cells from 16 CML patients by three‐colour flow cytometry. The mean percentage of cells expressing L‐selectin in the CD34++CD38+  ∼  ++ fraction from untreated CML patients was significantly lower, and that in the CD34++CD38− fraction tended to be lower than that from normal controls. Among 11 CML patients treated with interferon‐α (IFN‐α), the mean percentage of the cells expressing L‐selectin in the CD34++CD38− fraction from three patients with a low percentage of Ph1(+) cells in bone marrow was significantly higher than that from five patients with a high percentage of Ph1(+) cells. In addition, L‐selectin expression rate was inversely correlated to the percentage of Ph1(+) cells. There was no significant difference between the untreated patients and normal controls with regard to the expression rates of the other adhesion molecules in each CD34++ fraction except LFA‐1. These data suggest that decreased L‐selectin expression in CML CD34++ cells reflects one of the features of malignant CML progenitors.

Acute myelogenous leukemia with PIG-A gene mutation evolved from aplastic anemia-paroxysmal nocturnal hemoglobinuria syndrome.

We report a patient with aplastic anemia (AA)—paroxysmal nocturnal hemoglobinuria (PNH) syndrome who developed acute myelogenous leukemia (AML). Flow cytometric analysis showed that the leukemic cells in the bone marrow lacked CD59 antigen on their surface and were positive for P-glycoprotein. Heteroduplex and single-strand conformation polymorphism analysis followed by sequencing of the leukemic cells in the bone marrow disclosed 1 frameshift-type mutation in exon 2 of the phosphatidylinositol glycan-class A (PIG-A) gene, which deductively produces truncated PIG-A protein. These findings provide direct evidence that the leukemic cells evolved from the affected PNH clone. Cytogenetic analysis in the bone marrow in each stage of AA-PNH, AML, and at relapse of AML showed normal, −7, and −7 plus −20, respectively, showing evidence of a clonal evolution. Because complete remission of AML was not achieved by intensive chemotherapies, allogeneic peripheral blood stem cell transplantation (PBSCT) from the patient’s HLA-matched sister was performed successfully with recovery of CD59 antigen on bone marrow hematopoietic cells; however, leukemia relapsed 4 months after PBSCT. Leukemia derived from PNH may be resistant to intensive chemotherapy, and a highly myeloablative regimen may be required for stem cell transplantation to eradicate the PNH-derived leukemia clone.

Factors influencing survival in philadelphia chromosome positive chronic myelocytic leukemia

The prognostic value of several clinical and hematologic features, recorded at diagnosis, in chronic phase Ph1 positive chronic myelocytic leukemia (CML), was analyzed in 135 patients using life‐table analysis. About one third of patients were atomic bomb survivors and they had been examined twice a year before the diagnosis of CML. In general, features representing tumor cell burden, i.e., leukocyte count, spleen sizes, and absolute differential cell counts of all granulocyte series cells except myeloblasts affected survival significantly, while sex, age, hemoglobin, platelets, and features representing quality of leukemia, i.e., neutrophil alkaline phosphatase score, percent Ph1 positive cells in bone marrow, and percent differentials of all granulocyte series cells except promyelocytes and segmented neutrophils were all insignificant. Multivariate life‐table analysis was also performed using age, sex, hemoglobin, platelets, and leukocyte count as predictor variables. The result was that leukocyte was the single most important factor in this analysis and annual death rates between low risk (risk ratio < 0.8) and high risk (risk ratio > 1.4) differed considerably up to four years from diagnosis, indicating our formula to calculate risk ratio is valid as a grading parameter of chronic phase Ph1 positive CML within four years from diagnosis.

Blastic transformation in essential thrombocythemia. In vitro differentiation of blast cells into granulocytic, erythroid, and megakaryocytic lineages.

A 57‐year‐old man with essential thrombocythemia (ET) developed myelofibrosis, that progressed to a blastic transformation state. The characteristics of the blastic cells were serially studied both morphologically and phenotypically as well as in cell culture. The blastic cells that were first detected in peripheral blood had features of myeloid stem cells with slight differentiation toward megakaryocytic lineage. However, later in the course, most of the blastic cells were immature. During culture in the presence of human plasma‐derived serum (PDS), some blastic cells obtained at the initial stage differentiated, mainly to both granulocytes and macrophages morphologically, but later tended to differentiate into both megakaryocytes and macrophages. Finally the blasts appeared to have lost their ability to differentiate morphologically. However, the blasts formed mixed colonies consisting of erythroblasts, granulocytes, macrophages, and immature blasts when cultured in methylcellulose with PHA‐leukocyte conditioned medium. In addition, the blastic cells in suspension culture strongly expressed phenotypic features which are characteristic of erythroblasts, in the presence of both PDS and 12‐0‐tetradecanoylphorbol 13‐acetate (TPA), whereas they expressed features of megakaryoblasts in the presence of PDS alone. These results suggest that essential thrombocythemia is of myeloid stem cell origin. This is the first case in the literature in which a clonal evolution in ET has been followed closely, essential events were identified serially, and the blastic cells, which appeared as a result of the progression of ET, were found to have the capability to differentiate toward the three myeloid lineages.

Chronic myelogenous leukemia and Klinefelter's syndrome.

A case of chronic myelogenous leukemia with Klinefelters syndrome mosaicism in a 27‐yr‐old male is reported. Cytogenetic analysis provided evidence that the Philadelphia chromosome occurred monoclonally in the XXY cells but not in the XY cells.

XYY male and hematologic malignancy

Two cases of XYY male with refractory anemia with excess of blasts are reported, and previous reported XYY males with hematologic malignancy are reviewed. Altogether 26 cases were collected for analysis: acute myeloid leukemia (10), acute lymphocytic leukemia (seven), acute leukemia (two), chronic myelocytic leukemia (three), myelodysplastic syndrome (three), and essential thrombocythemia (one). The age at the time of diagnosis ranged in age from 7.5 to 81 years. In three of six XYY/XY mosaicism cases, XYY clone was associated with malignancy. However, in two cases XYY clone was not involved. The evidence presented here suggests that the event of an XYY male with hematologic malignancy is incidental rather than a genetic etiology.

L-selectin expression in CD34 positive cells in chronic myeloid leukemia.

L-selectin is a cell adhesion molecule, expressed on leukocytes and involved in the regulation of leukocyte traffic. This adhesion receptor is implicated in hematopoiesis by the interaction of hematopoietic stem cells and progenitors to stroma in the bone marrow microenvironment. We found that L-selectin expression on CD34++ cells from patients with chronic myelogenous leukemia (CML) is decreased or deficient, reflecting one of the features of malignant CML progenitors. In this review, we briefly describe the structure and function of L-selectin, and its role in hematopoiesis and its expression in leukemia and lymphoma. Finally, we discuss the abnormal adhesiveness of CML progenitor cells, and the role of L-selectin in this defect.