Platelet membrane early activation markers during prolonged storage

The relationship between platelet aging and early markers of membrane activ ation have not been defined clearly. Activation markers expressed during pr olonged storage are similar if not identical to those that appear after exp osure to thrombin. Using flow cytometry, we investigated platelet membrane expression of CD62P, CD63, and annexin V binding (i.e., loss of membrane as ymmetry) in platelets stored for up to 11 days under standard blood banking conditions. We compared five apheresis platelets to two random donor plate let concentrates, and to one pooled platelet preparation from six single pl atelet concentrates before and after exposure to thrombin. CD62P, CD63 expr ession, and annexin V binding increased during storage albeit with differen t kinetics. The differential increments observed between resting and thromb in (1 unit/ml) activated platelets showed an inverse correlation to storage time for CD62P, CD63, and annexin V binding, which was identical to publis hed survival curves. A difference between apheresis platelets and platelet concentrates was observed only on day 1. Our data indicate that the in vitr o platelet reserve activity to thrombin activation mirrors that of radiolab eled platelet survival in vivo and that platelet cross-sectional residual l ife span can explain their diminished capacity to respond to thrombin as a function of viability. (C) 1999 Elsevier Science Ltd. All rights reserved.