Abnormal phosphoenolpyruvate transport in erythrocytes of hereditary spherocytosis

The transport rates of phosphoenolpyruvate in erythrocytes from healthy individuals and from patients with hereditary spherocytosis were examined by incubating the cells with 10 mM phosphoenolpyruvate at 37 degrees C in the citrate buffer (0.10 M Na-citrate, 10 mM NaF, 5 mM glucose; pH 6.1 at 37 degrees C). The transport rate of phosphoenolpyruvate in erythrocytes of hereditary spherocytosis was 0.09 +/- 0.02 mumol/ml cells/min (mean +/- S. D., n = 7), whereas that in normal cells was 0.23 +/- 0.03 mumol/ml cells/min (mean +/- S. D., n = 7). The decreased rate of the transport seemed to be specific to the erythrocytes from patients with hereditary spherocytosis, since the rates in erythrocytes from patients with autoimmune hemolytic anemia, paroxysmal nocturnal hemoglobinuria, iron deficiency anemia and aplastic anemia were almost within normal range. Therefore, the decreased transport rate of phosphoenolpyruvate in erythrocytes of hereditary spherocytosis may be a reflection of some specific abnormality in the erythrocyte membrane. Moreover, the measurement of the transport rate of phosphoenolpyruvate may be used as a new diagnostic method for hereditary spherocytosis.