A peculiar pattern of expression of the transferrin receptor (CD71) by reticulocytes in patients given recombinant human erythropoietin (rHuEPO): a novel marker for abuse in sport?

To overcome the limitation of the currently adopted direct method to detect recombinant Human Erythropoietin (rHuEpo) abuse in sport, indirect analysis of blood parameters are increasingly used as part of the anti-doping strategies. The aim of the present work is to identify whether immunophenotype modifications on erythroid cells may be indicative of previous rHuEPO administration. The study was conducted on dialyzed patients under treatment with rHuEPO (DPT). Dialyzed patients without rHuEPO therapy (DP) and volunteer donors (H) were used as controls. The analysis of erythroid cells immunophenotype, performed using a multiparametric flow cytometry technique, showed a peculiar pattern of CD71 expression following rHuEPO treatment. In particular CD71 showed an increased expression in mature and intermediate reticulocytes and a surprisingly decreased expression in immature reticulocytes. In conclusion, the analysis of reticulocyte maturation stages with TO/CD71 double staining may be considered as a valid alternative indirect method for the detection of rHuEPO abuse.