Study on Internal Standards Applicable to the Detection of Recombinant Erythropoietin

With the discovery of the variant c.577del in the EPO gene, the procedure for detecting the presence of recombinant erythropoietin (rEPO) has become complicated and time-consuming. To address this situation, an rEPO confirmation method that uses reverse-normal immunopurification coupled with western blotting (WB) and sodium N-lauroylsarcosinate polyacrylamide gel electrophoresis (SAR-PAGE), which can detect the EPO variant (VAR-EPO) and rEPO with anti-VAR-EPO and anti-EPO antibodies, has been developed. Therefore, it is necessary to develop an internal standard (IS) that can be recognized by an anti-VAR-EPO antibody to monitor reverse immunopurification, ensuring the reliability and accuracy of the analysis. In this study, we constructed an IS based on VAR-EPO modified with polyethylene glycol (PEG) and then assessed its reliability and applicability in doping analysis. The data provided here show that the obtained PEGylated VAR-EPO can be used as an IS to monitor the detection of not only rEPO and VAR-EPO but also EPO receptor agonists in urine samples.