ABSTRACT
The use of growth factors in sports is restricted under the terms of the World Anti-Doping Code (WADC). While the beneficial effects of erythropoietin (EPO) on erythropoiesis and therefore its performance-enhancing properties have been well documented and established for decades, the aim of this study was to elucidate the relevance of the cytokine G-CSF in a doping control context, particularly concerning its influence on selected blood parameters representing central aspects of the Athlete Biological Passport. For that purpose, the effect of repeated subcutaneous granulocyte colony-stimulating factor (G-CSF) injections in therapeutic dosages (10 µg/kg/d) on white blood cells, erythrocytes, hemoglobin, hematocrit and percent reticulocytes was analyzed by using commonly employed fluorescence flow cytometry-based approaches. A total of 20 people were tested (14 male, 6 female) and both white blood cell count and reticulocyte percentages were found to significantly increase following a 5-day treatment with G-CSF. Simultaneously, all other volume-dependent parameters (red blood cell count, hemoglobin, hematocrit) slightly but significantly decreased. Due to the relevance of these measurands for the validity of blood tests for doping controls and the anecdotal evidence of G-CSF being potentially misused by elite athletes, G-CSF analyses might be indicated in case of unusually altered blood profiles.
