USE OF ANNEXIN V-FERROFLUID TO ENUMERATE ERYTHROCYTES DAMAGED IN VARIOUS PATHOLOGIES OR DURING STORAGE IN-VITRO

Recombinant human annexin V war bound covalently to 9 nm maghemite (ga mma/Fe2O3) nanoparticles, yielding annexin-ferrofluid (AnxFF), and use d to separate annexin-bound red blood cells (RBC) in a magnetic field and estimate their percentage in various bloods. Annexin binding in no rmal human RBC increased proportionately with storage from 8% on day 2 to 42% on day 100. Enhanced AnxFF binding was associated with various pathologies. Thus, normal blood contained 10.7+/-5.9% AnxFF binding R BC; bloods with normal sedimentation rates (albeit with some disease n ecessitating analysis) contained 23.5+/-6.2%, those with high sediment ation rates contained 51.5+/-12.3%; sickle cell anaemia patients' bloo d contained 50.0+/-3.3%, and bloods from patients with other pathologi es (deforming rheumatic disease, cancer necessitating chemotherapy, et c.) contained 58.6+/-7.6% AnxFF binding RBC. Enhanced Ca2+-dependent a nnexin binding reflects a loss of the asymmetric distribution of anion ic phospholipids in plasma membranes which may constitute a signal for the destruction of the modified cells by the reticuloendothelial syst em. Once these preliminary results are confirmed the determination of the fraction of AnxFF bound erythrocytes, following their magnetic sep aration, could prove a simple and rapid quality test for example in th e concert of blood transfusion.