Leukocyte contamination during blood transfusion can cause many adverse effects, such as the transmission of cell-associated infectious agents, febrile non-haemolytic reactions, graft-versus-host disease, and immunosuppression. While using leukodepleted blood components can minimise some of these adverse effects, the leukodepletion of all cellular blood components is costly. A more cost-effective alternative would be to supply leukodepleted blood components to at-risk patients only.