ALBERT

Description: Abstract 342 Background. Packed red cells (PC) stored in blood bank undergo a series of changes, so-called “storage lesion”, which increase with time. In view of some but not all recent studies, it is widely believed that transfusion with younger blood carries less risk of adverse reactions than older blood. However, there is no agreement on the “safe” age of blood, nor is it clearly understood why older blood may carry increased risks. The purpose of this study was to identify microparticle-related factors in stored PC at different time intervals that might pose risk of adverse effects. We investigated profiles of cell-derived microparticles (MP), particularly RBC-derived MP (RMP), in stored PC and assessed their procoagulant and inflammatory property. Methods. Twelve bags of fresh packed red cells (PC) of known blood types (A+, B+, AB+, O+) were obtained from blood bank (2-4 days since drawing). All were non-leuko depleted and were stored at 4°C. Time of receipt was considered day 0. At intervals of 0, 10, 20, and 30 days, 40 mL was withdrawn and centrifuged at 1000xg for 20 min to remove cells. The supernatants were then assayed for (1) quantity of different species of cell-derived MP by flow cyteometry comprising (a) RMP defined by CD235b; (b) LMP by CD45; (c) PMP by CD41; (d) EMP by CD144; (e) generic MP by Ulex Europaeus (Ulex) or Annexin V (AnV), (2) procoagulant activity by MP-mediated thrombin generation assay (TGA); (3) MP-mediated proinflammatory activity by CD 11b expression in neutrophils following incubation with RMP. Results. (1) MP Profiles. The time-course of generation of the MP subtypes varied considerably. For RMP, there was little increase before day 10, but then rose rapidly with time, to 180% at 20 days, and to 450% at 30 days. Small amounts of MP derived from leukocytes (LMP), platelets (PMP), and endothelia (EMP) were present in all bags at day 0, generally