Response of three classes of human erythroid progenitors to the absence of erythropoietin in vitro as a measure of progenitor maturity.

The effect of erythropoietin (Ep) deprivation (epoprival state) on plasma clot cultures of human bone marrow and peripheral blood erythroid progenitors was examined. In normal individuals, there was a marked reduction of CFUE derived colony expression if Ep was withheld from the culture for even one day. Peripheral blood BFUE retained substantial function during the epoprival state for up to 2 to 5 days while bone marrow-derived BFUE had intermediate sensitivity. Thus the capacity of erythroid progenitors to withstand incubation in semi-solid media in the absence of Ep is a characteristic of immature, rather than mature, erythroid progenitors.