Recombinant human erythroid potentiating activity enhances the effect of erythropoietin in mice

Endotoxin-free purified recombinant human erythroid potentiating activity (EPA) was administered to mice either alone or concomitantly with recombinant human erythropoietin (Epo). Epo treatment alone caused an increased hematocrit and reticulocyte count in the peripheral blood. In the spleen, the number of morphologically recognizable erythroid cells, CFU-E and BFU-E was also increased. Concomitant administration of EPA with Epo further enhanced erythropoiesis as judged by the same parameters. No significant effect on granulopoiesis was observed in association with Epo or combined Epo and EPA treatment. Our data indicates that EPA is active in vivo in augmenting the erythropoietic response to Epo.