Fragmentation and myelin formation in hereditary xerocytosis and other hemolytic anemias

Erythrocytes from a heterogeneous group of hemolytic anemias have been found to release acetylcholinesterase-enriched fragments and show myelin forms during ATP depletion in vitro. The highest amount of fragmentation was found in hereditary spherocytosis and xerocytosis, two inherited membrane defects. Our data suggest ATP depletion plays a role in producing fragmentation or myelin forms. The addition of external CaCl2 1 mM had no effect on the degree of fragmentation. However, propranolol hydrochloride, a cationic anesthetic that does not prevent ATP depletion, inhibited fragmentation and the appearance of myelin forms in both hereditary spherocytes and xerocytes. A more detailed study of the xerocyte fragments showed that they had the same protein composition as those from normal red cells, primarily integral membrane proteins and glycoproteins. The red cells from patients with PNH and G6PD deficiency had the shortest survival in vivo (51Cr) and produced the smallest amount of fragmentation and myelin forms in vitro, whereas xerocytosis with only mild to moderate hemolysis in vivo was associated with the highest amount of myelin forms and membrane fragments in vitro.