Pathogen inactivation/reduction technologies for platelet transfusion: Where do we stand?

Pathogen inactivation or reduction technologies for platelet components have been proposed to secure the microbial safety of this component, and particularly the microbial contamination. Transfusion-transmitted bacterial infections were substantially reduced by additive steps applied at different levels of the transfusion chain, but still killed one recipient each year or every other year in a country like France. Besides, pathogen inactivation and reduction stand for eliminating most viral and protozoa infections persisting in the separated blood component. In addition, because those processes attack nucleic acids, they also aim at substantially alleviating the risk of Transfusion Associates Graft versus Host Disease, as they attack lymphocytes still comprises within the component. Meanwhile, pathogen inactivation or reduction may inflict some damages to the platelet components, that are shown to be additive to the "natural" storage lesions linked to ageing. While it is in general assumed that such processes do not expose transfused patients to an over-risk of bleeding, and are safe, this does not mean that there are no detrimental consequences in the patients, even if not ascribed to as serious. Two such effects are now discussed or debated: the first one is the possible increase in the demand of platelet component, and the other one could be a possible risk of alloimmunisation especially when treated platelets are aged (over 5 days). Three processes have been made available by the industry, that differ in their chemical and physical (ultraviolet light illumination) characteristics. Two processes are largely used (one nationwide in two European countries) and the third one is still under clinical evaluation. This short review endeavored to critically present the main features of the processes and of their implementation.