Annexin V and platelet antigen expression is not altered during storage ofplatelet concentrates obtained with the AMICUS (TM) cell separator

During storage of platelet concentrate the so-called "storage lesion" occur s. During this time, platelets loose their morphological and functional cap acities that are necessary for proper in vivo efficacy following transfusio n. Annexin V represents a marker for apoptosis. In this study, Annexin V an d additional antigens were analyzed by flow cytometry. Platelet concentrate s were obtained with a new cell separator (AMICUS(TM) Separator, Fenwal). F ollowing apheresis, platelet units were stored for an experimentally prolon ged time of seven days. Daily aliquots of the platelet-rich plasma were obt ained to measure Annexin V and platelet antigens CD62p, CD63, CD41a, CD42b, and the binding of fibrinogen. All analyses were performed using flow cyto metry. During storage, no significant changes in mean channel fluorescence intensity (MCFI) of CD41a (P = 0.99) and CD42b (P = 0.29), percentage of CD 62p+ and CD63+ platelets (P = 0.23 for CD62p; P = 0.52 for CD63), and the b inding of fibrinogen to platelets occured (P = 0.85). Also, the expression of Annexin V remained constant with no significant change (P = 0.36). This study shows that antigens of platelets, obtained with the AMICUSTM cell sep arator are well preserved during storage. Regarding Annexin V, no obvious s igns of apoptosis can be detected by flow cytometry. These findings demonst rate the high degree of biocompatibility of the apheresis device and storag e container. (C) 1999 Elsevier Science Ltd. All rights reserved.