CLONAL ANALYSIS OF ERYTHROPOIETIN STIMULATED J2E CELLS REVEALS ASYNCHRONY DURING TERMINAL DIFFERENTIATION

J2E erythroid cells proliferate and differentiate in response to eryth ropoietin (epo), the red blood cell specific hormone. Using methylcell ulose colony assays and suspension cultures we have demonstrated that nearly all the cells stimulated by epo synthesized haemoglobin. To ach ieve maximum production of haemoglobin J2E cells had to be treated wit h epo for only 6 h; hormone added subsequently did not enhance haemogl obin synthesis. Although virtually all viable J2E cells produced haemo globin, the cells matured morphologically at different rates. Thus, up on exposure to epo J2E cells become committed to erythroid terminal di fferentiation but proceed in an asynchronous manner.