Diphenylhydantoin and fragility of erythrocytes in normal subjects and in patients with hereditary spherocytic anemia.

To study the effects of diphenylhydantoin (Dilantin, DPH) on membrane function, DPH was incubated with erythrocytes from normal individuals and from patients with congenital spherocytic hemolytic anemia and osmotic fragility measured. The resulting curves show that DPH reduces the osmotic fragility of normal and spherocytic erythrocytes. In the presence of ouabain, DPH still had a protective effect on erythrocytes even though ouabain alone increases hemolysis of erythrocytes at certain saline concentrations. This study shows that erythrocyte fragility can be manipulated in vitro and provides a basis for studies in vivo.