New screening protocol for recombinant human erythropoietins based on differential elution after immunoaffinity purification

A screening method able to differentiate recombinant human erythropoietins (rhEPOs) and analogues like CERA from human urinary erythropoietin (uhEPO) is described. The method is based on the discrimination between isoforms observed when the protein is eluted under acidic followed by basic conditions from immunoaffinity microtiter wells. From a comparison with the complex IEF protocol currently applied in anti-doping analysis, the newly developed assay procedure is amenable to wide screening application and presents good resolving power between rhEPOs and uhEPO.