A novel CD10-positive erythroid cell line, RM10, established from a patient with chronic myelogenous leukemia

A novel erythroid cell line, RM10, was established from a long-term bone marrow culture of a patient with chronic myelogenous leukemia (CML). RM10 cells were positive for periodic acid Schiff (PAS), but negative for peroxidase and dual esterase. RM10 cells had la, pre B (CD10), myeloid (CD13, CD14, CD33) and erythroid (glycophorin A) markers, but had no other lymphoid, megakaryocytic, or mesenchymal cell markers. RM10 cells spontaneously synthesized hemoglobin, which was markedly enhanced with hemin. Isoelectric focusing of the cell lysates and northern blot analysis of the total cellular RNA revealed hemoglobin synthesis in the cells. Using 125I-labeled recombinant human erythropoietin (Epo), two classes of Epo receptors were demonstrated in the RM10 cells. However, Epo did affect neither growth nor erythroid differentiation of the cells. RM10 cells rapidly differentiated to monocytic cells in the presence of 12-0-tetradecanoylphorbol-13-acetate, and simultaneously expressed glycoprotein IIb/IIIa. RM10 cells had Philadelphia chromosome (Ph), and expressed p210bcr-abl using immunoprecipitation with anti-c-abl and anti-phosphotyrosine antibodies. These results indicate that the RM10 cells have the characteristics of multipotential hemopoietic cells originating from Ph-positive CML and that high affinity Epo receptor class is not a sufficient condition for Epo responsiveness.