Early circulating erythroid progenitor cells and expression of erythropoietin receptors in sickle cell disease.

The ability of circulating progenitor cells from 22 patients with sickle cell disease (SCD) to develop erythroid colonies was studied in vitro in the presence or absence of growth factors (5637-CM and erythropoietin). In both conditions, SCD patients presented significantly higher numbers of circulating burst-forming unit-erythroid (BFU-E/5x10[5]MNC) when compared to control subjects. The study of the expression of erythropoietin receptors revealed an increased level in SCD patients. Moreover, there was a correlation between both stimulated and autocrine (without stimulus) BFU-E and the expression of erythropoietin receptors. These results are of particular interest since they indicate that the phenomenon of spontaneous BFU-E-derived colonies observed in SCD patients may be due to an increased expression of erythropoietin receptors.