A novel leukemic cell line with an 8;21 chromosome translocation, designated as Kasumi-1, was established from the peripheral blood of a 7-year-old boy suffering from acute myeloid leukemia (AML). The Kasumi- 1 cells were positive for myeloperoxidase showing a morphology of myeloid maturation. The response in proliferation assay was observed in the culture with interleukin-3 (IL-3), IL-6, granulocyte colony- stimulating factor (G-CSF), and granulocytemacrophage CSF (GM-CSF), but not with IL-1 or IL-5. Neither granulocytic nor eosinophilic maturation was observed in the liquid culture by the addition of dimethyl sulfoxide, G-CSF, or IL-5, respectively. In contrast, induction of macrophagelike cells was seen by the addition of phorbol ester. This is the first report of a human AML cell line with t(8;21) that has characteristics of myeloid and macrophage lineages. The cell line could be a useful tool for elucidating the pathophysiology of AML with t(8;21).

Twenty-three acute myelocytic leukemia (AML) patients with t(8;21) chromosomal abnormality, all classified as M2 (French-American-British [FAB] classification), were investigated. Blastic cells from all patients were positive for the stem cell-associated antigens, CD34 and HLA-DR, and the immature myeloid antigens, CD13 and CD33. The nonblastic leukemic cells expressed the more mature myeloid antigens, CD11b and CD15, with loss of the immature phenotype. The incidence of positivities for the stem cell-associated antigens, CD34 and HLA-DR, in t(8;21) AML cells was significantly higher in comparison with those in other AML showing granulocytic differentiation (M2 or M3). AML cells with t(8;21) also showed some phenotypic abnormalities. Frequent expression of CD19 was found in the blastic population of t(8;21) AML (18 of 23 cases) without other B-cell antigens and Ig gene rearrangements. CD19 expression was confirmed by immunocytochemistry and Northern blotting. The CD19+ blastic cells coexpressed both CD34 and HLA-DR. In addition, CD33+ cells among the blastic fraction in t(8;21) AML cells were fewer in number than in those of M2 or M3 AML without t(8;21). Our findings indicate that leukemic blasts of t(8;21) AML commonly express CD19 while preserving the stem cell-associated antigens, and differentiate into the granulocytic pathway with discordant maturation such as low CD33 expression.

A novel leukemic cell line with an 8;21 chromosome translocation, designated as Kasumi-1, was established from the peripheral blood of a 7-year-old boy suffering from acute myeloid leukemia (AML). The Kasumi- 1 cells were positive for myeloperoxidase showing a morphology of myeloid maturation. The response in proliferation assay was observed in the culture with interleukin-3 (IL-3), IL-6, granulocyte colony- stimulating factor (G-CSF), and granulocytemacrophage CSF (GM-CSF), but not with IL-1 or IL-5. Neither granulocytic nor eosinophilic maturation was observed in the liquid culture by the addition of dimethyl sulfoxide, G-CSF, or IL-5, respectively. In contrast, induction of macrophagelike cells was seen by the addition of phorbol ester. This is the first report of a human AML cell line with t(8;21) that has characteristics of myeloid and macrophage lineages. The cell line could be a useful tool for elucidating the pathophysiology of AML with t(8;21).

The expression of interleukin-2 receptors (IL-2R) was examined in 328 adult patients with non-T-cell (non-T) acute leukaemia and blast crisis of chronic myelocytic leukaemia (CML.BC) using two monoclonal antibodies, anti-Tac for IL-2R alpha chain (IL-2R alpha) and Mik beta 1 for IL-2R beta chain (IL-2R beta). Leukaemic cells in the following cases were positive for anti-Tac; 28/192 of acute myelocytic leukaemia (AML), 24/44 CML-BC, 4/28 CD19(+)CD10(-) acute lymphoblastic leukaemia (ALL), and 20/64 common ALL (c-ALL). IL-2R beta was not detected on leukaemic cells of any case examined. Eleven of IL-2R alpha(+) AML were derived from myelodysplastic syndrome. None of the IL-2R alpha positive leukaemic cells responded to exogenous recombinant human IL-2 (rhIL-2) in culture. In addition, IL-2R alpha expression on non-T leukaemic cells was closely correlated with coexpressing different lineage markers and the presence of the Philadelphia abnormality. Marked increase of serum soluble IL-2R alpha was demonstrated in the IL-2R alpha(+) patients examined. Clinically, the IL-2R alpha(+) patients showed significantly lower response to chemotherapy and poorer prognosis than IL-2R alpha(-) patients. Our results clearly indicate the diagnostic importance of IL-2R alpha expression in non-T acute leukaemia with a close relation to the particular cellular characteristics and the prognosis.

Ten patients with acute leukemia after primary myelodysplastic syndrome (MDS-AL) were examined to clarify the biologic nature of the leukemic cells in comparison with that of de novoacute myelocytic leukemia (AML). The morphologic and cytochemical features of the leukemic cells from all these patients corresponded well to those of de novo AML, and they were diagnosed with MDS-AML. Phenotypically, the frequent expression of the lymphocyte activation antigens, CD25 and CD30, was characteristic in MDS-AML. The in vitro response of MDS-AML cells to various growth factors was similar to that of de novo AML cells. Transforming growth factor ,81 (TGFj31) suppressed YELODYSPLASTIC syndrome (MDS) is recog-