Erythrocyte phosphatidylserine exposure in β-thalassemia.

Abstract

[ABS]Phospholipid asymmetry is well maintained in erythrocyte (RBC) membranes with phosphatidylserine (PS) exclusively present in the inner leaflet. Eryptosis, the suicidal death of RBCs, is characterized by cell shrinkage, membrane blebbing, and cell membrane phospholipids scrambling with PS exposure at the cell surface. Erythrocytes exposing PS are recognized, bound, engulfed, and degraded by macrophages. Eryptosis thus fosters clearance of affected RBCs from circulating blood, which may aggravate anemia in pathological conditions. Thalassemia patients are more sensitive to the eryptotic depletion and osmotic shock which may affect RBC membrane phospholipid asymmetry. We aimed in this work to determine the RBC PS exposure in splenectomized and nonsplenectomized β-thalassemia major (β-TM) patients and correlate it with the clinical presentation and laboratory data. RBCs were stained for annexin V to detect phosphatidylserine (PS) exposure in 46 β-TM patients (27 splenectomized and 19 nonsplenectomized) compared to 17 healthy subjects as a control group. We observed a significant increase in RBC PS exposure in β-TM patients compared to control group (P = .0001). Erythrocyte PS exposure was significantly higher in splenectomized β-TM patients compared with nonsplenectomized β-TM patients (P = .001). No correlation was found between RBC PS exposure and clinical or hematological data of β-TM patients, but there was a positive correlation between RBC PS exposure and ferritin level in β-TM patients have higher levels of RBC PS exposure, and splenectomy was shown to aggravate RBC PS exposure without aggravation of anemia.