[Leukodepletion of labile blood products]

On the first of April 1998, French authorities decided on the systematic leukodepletion of two blood products: Red blood cell concentrates and platelet concentrates coming from homologous donors. This measure is based on the following principle arguments: Purification of the therapeutic product, as white cells are just passenger cells. White cells interfere with the red cells and the platelets during storage, deteriorating the overall quality of the blood product. There are multiple effects on the recipient of allogeneic leucocytes: CMH II structures stimulation of the host immune system; graft versus host reaction; cytokines secretion and mediators release; class I anti-HLA allo-immunisation; in general, immunomodulation (immunosuppression); intraleukocyte infectious agent transmission. Several techniques make leukodepletion in blood products possible: 1. For the red cells, just one technique is basically used today: filtration either when the red cell concentrate is being prepared (filtering the whole blood), or after having obtained the concentrate, filtering that. The filters used today are from a third generation and their efficiency is above 99.9%. The final product contains thus less than 1.10(6) per unit, whereas the initial product contained 1.10(9) per cent. 2. For the platelets, apheresis technology makes it possible to obtain platelet concentrates directly leucoreduced (1.10(5)). However, there are still two questions: is this process also useful for plasma? and what about for autologous blood products?