Does General Leukocyte Depletion Provide Any Better Clinical Outcome?

Abstract

Variant Creutzfeldt-Jakob disease (vCJD) is associated with the BSE epidemic, and the pathological prion protein (PrF^res) of vCJD patients closely resembles that in BSE affected cattle. It is presently accepted that vCJD is a result of ingestion of contaminated beef [1]. Although classic CJD has never been associated with transfusion of blood or blood products, vCJD raises more concern. Considering the crossing of the species barrier, the vCJD agent might be or become more infectious to man by adaptation. The vCJD agent is associated with involvement of lymphatic tissues, and the lymphatic system was associated with to the development of prion disease [2,3]. As a result, leukocyte depletion of blood products was suggested as a preventative measure. However classic CJD, and vCJD have never been documented in a transfusion associated event [4]. This includes the recipients of blood products from thousands of donors: the haemophilia patients. In animal models, PrF^res can be spiked into blood fractions and such infected blood fractions have been used to perform transmission experiments. Intracranial inoculation of infected blood fractions does seem to transmit prion disease, with different efficacy but experiments with the intravenous route of inoculation were largely unsuccessful (Brown P, personal comm.). It remains to be seen whether reduction of the total number of leukocytes in blood products is relevant, or if prions escape such measures by their presence in the plasma or other fractions.