Erythropoietin Assays Using Iron59 Incorporation into Blood and Spleen of the Polycythemic Mouse

Abstract

Mice rendered polycythemic by transfusion with hemologous cells were injected with graded doses of erythropoietin and Fe59 citrate was injected 24 hours later. Fe59 incorporation into spleen and peripheral blood was determined at intervals after injection of the isotope. In stimulated animals, maximal incorporation of Fe59 into the spleen occurred at 8 hours and into the blood by 48 hours. In unstimulated control animals, the isotope was minimally present in the blood at 48 hours. The optimal assay for the detection of small amounts of erythropoietin was found to be that which measured the incorporation of Fe59 into the peripheral blood of the polycythemic mouse 48 hours after the injection of the isotope.