Universal leucodepletion is being introduced in the U.K. to reduce a theoretical risk of Creutzfeldt-Jakob disease (CJD) transmission. If CJD infectivity is associated with leucocytes, any cell fragmentation associated with filtration could reduce the potential benefit. Four types each of whole blood, red cell and platelet leucodepletion filters were assessed after holding of blood units for at least 4 h at 22 degrees C. In all cases the mean residual leucocyte content was <1 000 000 per unit, with only two individual filtered whole blood units having a leucocyte content exceeding this. Evidence of leucocyte fragmentation during filtration was sought but not found by assay of soluble elastase, beta-thromboglobulin and normal prion protein, as well as by isotopic labelling of leucocyte external membrane. These preliminary studies indicate that it was possible to prepare leucodepleted blood components by filtration at room temperature, and that this appeared not to be associated with overt cell fragmentation. Definitive demonstration that fragmentation does not occur requires the development of improved general (non-specific) assays for cell membrane fragments.

Whole blood donations were collected into 0.5CPD anticoagulant in PL-146 plastic. This was shown to improve the stability of plasma FVIII levels when compared with CPD. RAS-2 was used as additive and this improved the in vitro properties of the red cells, such that post processing 2,3-DPG levels were maintained for 21 days and ATP levels were maintained for 28 days. Whether or not such improvements in red cell properties yield a benefit in clinical use remains to be established.