Erythrocyte populations in pyruvate kinase deficiency anaemia following splenectomy. II. Cell deformability.

The deformability of three previously described morphological populations of erythrocytes from splenectomized pyruvate kinase (PK) deficient patients was assessed using both Nucleopore filtration and micropipette techniques. Mean deformability was decreased in fresh cells from all patients studied. Selective measurements indicated that immature lobulated reticulocytes in each patient were the least deformable cells, followed by bizarre echinocytes characterized by a hyperviscous behaviour, and by thin macrocytic discocytes whose values were closest to those of control erythrocytes. We conclude that poorly deformable reticulocytes in these patients, after initial trapping in the spleen, are unable to return to the circulation because of their inordinate dependence on mitochondrial oxydative phosphorylation for maintenance of a sufficient intracellular concentration of adenosine triphosphate (ATP); hence their rapid and selective destruction. Splenectomy therefore may be beneficial by allowing such cells to mature more slowly in the circulation of these patients until they develop crenation and hyperviscosity, two manifestations of profound ATP depletion possibly leading to destruction by the liver.