2 CHRONIC MYELOGENOUS LEUKEMIA-CELL LINES WHICH REPRESENT DIFFERENT STAGES OF ERYTHROID-DIFFERENTIATION

We established two cell lines, YN-1 and Y-1K, from the peripheral bloo d of two chronic myclogenous leukaemia patients in blastic crisis. Cha racterization of the YN-1 and Y-1K cells revealed that these cells exp ressed erythroid lineage markers. However, there was a marked differen ce in the level of gamma-globin mRNA and haemoglobin in YN-1 and Y-1K cells. YN-1 contained approximately 1-5% benzidine-positive staining c ells, whereas no benzidine-positive cells were observed in Y-1K cells. Haemoglobin production in YN-1 cells was markedly increased with vari ous chemical inducers of erythroid differentiation, but was not in Y-1 K cells. In contrast, Y-1K cells expressed CD34 stem cell antigen and CD41 megakaryocyte-specific antigen. These observations suggested that , although both cell lines were committed to the erythroid lineage, ea ch cell line represented a distinct differentiation stage in the eryth roid differentiation programme. Y-1K seemed to correspond to an early stage of cells in erythroid lineage, whereas YN-1 represented a more a dvanced stage in human erythropoiesis.