Glucose-6-phosphate-dehydrogenase-deficient erythrocytes have an impaired shape recovery mechanism

In the human erythrocyte, the maintenance of the biconcave disc shape is important for cell viability as well as cell function. Previous studies have indicated the involvement of the hexose monophosphate shunt in the recovery of discoid shape after perturbation of echinocytic agents. In glucose-6-phosphate-dehydrogenase-deficient (Gd^-) erythrocytes, the shunt activity is significantly decreased; thus, it might be expected that the shape recovery rate of Gd^- erythrocytes would be decreased. We show here that shape recovery rates in the presence of the shunt stimulator methylene blue are as much as 5-fold lower in Gd^- erythrocytes. We also show that the protease inhibitor, N-α-tosyl-1-phenylalanine-chloromethyl ketone, has no effect on shape recovery in Gd^-, whereas it increases normal cell shape recovery rates by 10-30-fold at 50 μM and causes cupping at 200 μM (see companion article by Alhanaty et al.). These changes are not due to reticulocytosis, as other hemolytic disorders do not show such changes. Further, both chronic hemolyzing Gd^- and A^-Gd^- variants show similar abnormal shape recovery behavior, whereas the extent of hemolysis is quite different between variants. Thus, the activity of the hexose monophosphate shunt appears to have a dramatic effect on the rate of reversal of echinocytosis. The lack of shunt activity of Gd^- cells would necessarily impair their ability to recover normal shape after perturbation.