Acceleration of erythropoiesis mediated by erythroid accelerating factor (Eaf) In very early stage of drug induced hemolysis in rats

Abstract Erythroid accelerating factor (EAF) is a peculiar factor because the activity is definitely exhibited in an early stage of hemolytic stress in rats. A presumption can be made that EAF contributes to the acceleration of erythroid differentiation during initial period of sudden loss of erythrocytes. To further assess the relationship between serum EAF and a rapid rise of erythropoiesis in response to acute reduction of red blood cells, We determined the sequential changes of serum EAF and Epo in concomitant with blood parameters, bone marrow (BM) CFU-E and the erythroblastic islets in spleens at short intervals from 0time through 24h after acetylphenyhydrazine (APH) injection to induce hemolysis in rats. Serum EAF was significantly elevated as early as 6h following APH injection, reached a peak at 24h. On the other hand, serum Epo levels were gradually increased from 12h, with peaking on day 3 of the experiment. The number of colonies derived from CFU-E and erythroblastic ratios in BM showed peak increases at 8h after injection of APH. Histologic analysis of spleens revealed that the erythroblastic islets increased from (+) to (3+) at 6h. These results suggest that EAF mediates an early enhance of erythropoietic process during initial period of urgent anemia as acute hemolysis.