Erythrocyte Phosphatidylserine Exposure in β-Thalassemia

Phospholipid asymmetry is well maintained in erythrocyte (RBC) membranes with phosphatidylserine (PS) exclusively present in the inner leaflet. Eryptosis, the suicidal death of erythrocytes, 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 erythrocytes 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 erythrocyte PS exposure in splenectomized and nonsplenectomized β-thalassemia (β-TM) patients and correlate it with the clinical presentation and laboratory data.

RBCs were stained for annexin V (AV) 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 reported significant increase in erythrocyte PS exposure in β-TM patients compared to control group (p=0.000). Erythrocyte PS exposure was significantly higher in splenectomized β-TM patients as compared with nonsplenectomized β-TM patients (p=0.001). No correlation was found between erythrocyte PS exposure and clinical or hematological data of β-TM patients but there was positive correlation between erythrocyte PS exposure and ferritin level in β-TM patients.

These findings suggest that β-TM patients have higher level of erythrocyte PS exposure and splenectomy was shown to aggravate erythrocyte PS exposure without aggravation of anemia.