Impact of the platelet washing process on in vitro platelet properties, and the levels of soluble CD40 ligand and platelet-derived microparticles in the storage media.

<bold>Background: </bold>A new platelet (PLT) additive solution, bicarbonated Ringer's solution supplemented with acid-citrate-dextrose Formula A, termed BRS-A, as well as a new automated closed system cell processor for washing PLTs have recently been developed. This study evaluated the in vitro properties of PLTs with the automated system versus the manual method, using the BRS-A additive solution for washing and storage.<bold>Methods: </bold>ABO-identical apheresis PLTs in 100% plasma were pooled and split equally for control (in 100% plasma or a manual method) and test (ACP215 automated system) units. In vitro characteristics of PLTs washed with the automated system were compared to those of PLTs in 100% plasma (Study 1) or washed with a manual method (Study 2) during the 7-day storage.<bold>Results: </bold>In Study 1, hypotonic shock response, aggregation response, mitochondrial membrane potential, adenosine triphosphate, and CD42b mean fluorescence intensity were comparable in the control and test groups during the 7-day storage. CD62P expression was lower in the test group than controls on Days 3 and 7. The level of platelet-derived microparticles (PDMPs) in the test group on Days 1 and 2 were higher than those in controls. In contrast, the levels of soluble CD40 ligand (sCD40L) and regulated upon activation of normal T-cell expressed and secreted (RANTES) in the test units were lower than controls. In Study 2, no significant differences were found in all in vitro properties except for PLT count and the levels of PDMPs in the test units were higher than controls during storage.<bold>Conclusion: </bold>Apheresis PLTs washed with the automated system using BRS-A additive solution maintained in vitro properties during storage. Washing methods influenced PDMP levels but not sCD40L and RANTES. [ABSTRACT FROM AUTHOR]