Erythroid phosphatidyl serine exposure is not predictive of thrombotic risk in mice with hemolytic anemia

Thrombosis is a major complication of human hemolytic anemias such as sickl e cell disease, thalassemia, and severe hereditary spherocytosis (HS). Mice with severe HS and severe hereditary elliptocytosis (HE) also suffer from thrombosis, with incidences ranging from 15 and 22% in beta-spectrin- and a nkyrin-deficient mice, respectively, to 85 to 100% in alpha-spectrin-defici ent and band 3 knockout mice. A contributing factor to thrombosis could be loss of phospholipid asymmetry of the mutant red blood cells (RBCs), with c oncomitant exposure, of the aminophospholipid phosphatidylserine (PS). Incr eased PS exposure occurs in RBCs from sickle cell and thalassemia patients and in RBCs from band 3-deficient mice. To determine if increased PS exposu re correlates with thrombotic risk in HS and HE mice with ankyrin, beta-spe ctrin, and alpha-spectrin deficiencies, measurements of FITC-labeled annexi n V binding to externalized PS on RBCs were performed. PS exposure is eleva ted in all mice with HS and HE, but the percentage of RBCs with exposed PS does not correlate with thrombotic risk in these mice. (C) 2000 Academic Pr ess.