Gel card kit to detect recent homologous blood transfusion for anti-doping purpose. A proof of concept and assessment of limitations.

Homologous blood transfusion (HBT) is used illicitly by some athletes to increase red blood cell (RBC) mass. The cytofluorometric techinique detects HBT by distinguishing between two different RBC populations. Although effective, this method is costly and time-consuming. Gel card kits (ID-Card, BioRad), which are widely used in clinical practice, offer faster and more cost-effective alternative. This study evaluates the ability of Gel cards to differentiate between two RBC populations, when compared with cytofluorometry. Blood samples from volunteers were phenotyped for minor antigens (C, c, E, e, K, k, Jka, Jkb, Fya, Fyb, S and s) using flow cytometry. Non-compatible blood samples, differing in minor antigens groups, were mixed in different proportions (10%, 5% and 3% of donor blood). Gel cards were able to detect 5% of the minor population when the donor expressed C, c, E and e antigens. The limit of detection for K, Jka and Jkb antigens is 3%. However, Gel cards were not able to detect double RBC population when the donor expressed these antigens. Similarly, Gel cards could not distinguish between two RBC populations differing in Fya, Fyb, S and s expression, as the antigen-positive cells were not concentrated at the top of the Gel but were instead dispersed throughout it. Further studies are required to evaluate the ability of Gel cards to detect other antigens (e.g., M, N, P1, Le