Abstract
The deformability of erythrocytes from 30 healthy controls and from 10 patients with pyruvate kinase (PK) deficiency in different states of red blood cell (RBC) maturation has been determined by cell filtration through polycarbonate sieves.
The deformability of the whole RBC population from patients with a mild clinical course was with a flow rate of 16–20 μl/sec markedly decreased, compared to the controls (54 ± 4μl/sec). Red blood cells from patients with severe degree of hemolysis showed even lower flow rates (4–8μl/sec) depending on the counts of reticulocytes. Separation of the different RBC-fractions was obtained by density gradient centrifugation. Normal “young” erythrocytes are more deformable than “old” erythrocytes showing in filtration experiments flow rates between 60–65 μl/sec, compared to the old cells, which exhibited a velocity of 40–45 μl/sec. Flow rates of the reticulocytes from all patients, independent from their clinical condition, had a value of 5–10 μl/sec. The flow rates of their “old” cells, however, very well agree with the degree of hemolysis. In case of mild clinical course the flow rates of the “old” cells were 15–45μl/sec whereas in case of severe disease the flow rates were even more decreased (5–15μl/sec).
The filtration rate of the whole red blood cell population apparently can be regarded as the sum of the filtration rates of the single fractions and the low total filtration rate of cells from patients with PK deficiency is caused mainly by the rigidity of reticulocytes present in their whole blood. The results of these rheological investigations support earlier kinetic and electrophoretic studies with enzymes from patients suffering from PK deficiency, where could be demonstrated that reticulocytes from normal controls and from patients with PK deficiency showed no deviating behaviour, whereas the erythrocytes do deviate, thus suggesting a perturbation of their maturation process.
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