Leukoreduction and blood-borne vCJD transmission risk

Risk assessments for transmission of variant Creutzfeldt-Jakob disease predicted that leukocyte reduction would be inefficient at preventing transmission of the disease by blood transfusion. Nevertheless, approximately 14 years ago, a significant proportion of European countries decided to implement leukocyte reduction treatment within their human blood supplies in order to mitigate the risk of human prion disease transmission.

Current epidemiological studies seem to indicate that leukocyte reduction has had a positive impact on reducing the risk. In addition, over the last 5 years, various experimental studies carried out in animal models have confirmed that leukocyte reduction provides a high, but not absolute, protection against transmission of prion disease by blood transfusion. Observations that show the efficacy of blood-borne prion transmission is more dependent on the viability of leukocytes than the level of infectivity present in the blood product make a significant contribution to understanding the risk of prion infection by blood transfusion.

Considering the potential for significant numbers of subclinical variant Creutzfeldt-Jakob disease individuals in at least the United Kingdom, these findings strongly support the continuation of systematic leukoreduction for blood donations collected in individuals born before the effective prevention of human dietary exposure to bovine spongiform encephalopathy.