Quantitative expression of erythropoietin receptor (EPO‐R) on acute leukaemia cells: relationships between the amount of EPO‐R and CD phenotypes, in vitro proliferative response, the amount of other cytokine receptors and clinical prognosis

Abstract

Expression of erythropoietin (EPO) receptor (EPO‐R) was analysed in leukaemia cells from 150 patients with acute myeloid leukaemia (AML) or acute lymphoblastic leukaemia (ALL). EPO‐R was expressed in 81 (60%) out of 136 AML, and in vitro treatment with EPO led to proliferation of leukaemia cells in 13 (16%) out of 81 AML examined. EPO‐R expression and in vitro response to EPO were observed in all subtypes of AML according to the French–American–British (FAB) classification. All eight patients with FAB‐M6 expressed EPO‐R, and one out of four showed an in vitro response to EPO. Although there was no significant correlation (r = 0.2522) between the amount of EPO‐R and the in vitro response to EPO, all of the AML patients who showed in vitro response expressed EPO‐R. Stem cell factor significantly enhanced both EPO‐R expression and in vitro response to EPO. Interleukin‐3 tended to increase in vitro response to EPO. CD phenotypes, the amount of granulocyte colony‐stimulating factor (G‐CSF) receptors and the amount of TPO receptors had no significant relationship with the amount of EPO‐R. Patients with both EPO‐R expression and in vitro response to EPO had shorter duration of complete remission than those without EPO‐R (P = 0.0053). EPO‐R was expressed in four (29%) out of 14 ALL, and none out of five ALL showed in vitro response to EPO.