Enhanced erythrocyte apoptosis in sickle cell anemia, thalassemia and glucose-6-phosphate dehydrogenase deficiency

Erythrocyte diseases such as sickle cell anemia, thalassemia and glucose-6-phosphate dehydrogenase deficiency decrease the erythrocyte life span, an effect contributing to anemia. Most recently, erythrocytes have been shown to undergo apoptosis upon. increase of cytosolic Ca2+ activity. The present study has been performed to explore whether sickle cell anemia, thalassemia and glucose-6-phosphate dehydrogenase deficiency enhance the sensitivity of erythrocytes to osmotic shock, oxidative stress or energy depletion, all maneuvers known to increase cytosolic Ca2+ activity. To this end, annexin binding as an indicator of apoptosis has been determined by FACS analysis. Erythrocytes from healthy individuals, from patients with sickle cell anemia, thalassemia or glucose-6-phosphate dehydrogenase deficiency all responded to osmotic shock (up to 950 mOsm by addition of sucrose for 24 hours), to oxidative stress (up to 1.0 mM tetra-butyl-hydroxyperoxide tBOOH) and to energy depletion (up to 48 hours glucose deprivation) with enhanced annexin binding. However, the sensitivity of sickle cells and of glucose-6-phosphate dehydrogenase deficient cells to osmotic shock and of sickle cells, thalassemic cells and glucose-6-phosphate dehydrogenase deficient cells to oxidative stress and to glucose depletion was significantly higher than that of control cells. Annexin binding was further stimulated by Ca2+ ionophore ionomycin with significantly higher sensitivity of sickle cells and glucose-6-phosphate dehydrogenase deficient cells as compared to intact cells. In conclusion, sickle cells, thalassemic cells and glucose-6-phosphate dehydrogenase deficient erythrocytes are more sensitive to osmotic shock, oxidative stress and/or energy depletion, thus leading to enhanced apoptosis of those cells. The accelerated apoptosis then contributes to the shortened life span of the defective erythrocytes. Copyright (C) 2002 S. Karger AG, Basel.