Erythrocyte Pyruvate Kinase Activity Research Articles

Mechanisms of the acquired erythrocyte enzyme deficiencies in blood diseases

Acquired enzymatic activity defects of erythrocyte pyruvate kinase, glucose phosphate isomerase and phosphofructokinase have been studied in patients with acute myeloid leukemias, sideroblastic refractory anemias and unclassified acquired dyserythropoiesis. 6 patients with acute myeloid leukemia had a lowered erythrocyte pyruvate kinase activity; in 5 of them the concentration of the “pyruvate kinase ”-antigen was parallely decreased, in such a manner that the ratio enzyme activity / immunologie reactivity (i.e. the molecular specific activity) was normal. In 1 patient with acute leukemia, 4 with refractory anemia and 1 with acquired dyserythropoiesis the defect of the pyruvate kinase activity was associated with a normal antigen concentration (and, therefore, the molecular specific activity in whole hemolysate was lowered). The enzyme activity was restored by incubation with SH reagents in two cases and by partial purification as often as it was performed. The electrofocusing pattern of erythrocyte pyruvate kinase was normal in both these types of defects. In two patients with so-called “acquired dyserythropoiesis” an erythrocyte glucose phosphate isomerase deficiency has been detected; in both the cases it was associated with a parallel decrease of the antigen concentration. The residual enzyme had a normal electrofocusing and electrophoretic pattern and a normal heat stability; the enzyme activity could not be restored by any treatment. In 1 patient with erythroleukemia and in 1 other with acquired dyserythropoiesis the erythrocyte phosphofructokinase activity was lowered. The enzyme activity was not restored by cross incubation in isologous plasma or by the SH reagents. In one case immunologie study could be performed, kinase. Whether or not this finding is typical of the foetal erythrocytes is now under study in our laboratory. In conclusion the direct mechanism of the acquired red cell enzyme defects in some hematological diseases is not single and seems to involve either a nongenetic alteration of the enzyme after its synthesis or a modification of the enzyme-synthesis rate. In different patients some enzyme defects can be due to different mechanisms, and in a single patient several enzyme defects can also be due to different mechanisms.

Erythrocyte pyruvate kinase in experimental diabetes

Pyruvate kinase activity in erythrocytes and liver homogenates of alloxan diabetic rats and control animals was measured. The mean level of erythrocyte PK in alloxan diabetic animals was 6.72 ± 1.17 IU/g Hb. The mean level in control animals was 6.68 ± 1.75 IU/g Hb. In diabetic animals the mean level of liver PK activity was 0.077 ± 0.55 IU/mg protein. The mean level in controls was 0.305 ± 0.076 IU/mg protein. The results suggest that nongenetic variations observed in PK levels in human erythrocytes are not attributable to variations in insulin level.

61. Pyruvate kinase deficiency, a family study

A 3-year-old girl with pyruvate kinase deficiency has been investigated together with her family. Erythrocyte survival studies with 51Cr-labeled donor cells in the patient's circulation showed a half life of only 17 days. Direct Coomb's test was negative and cold agglutinin titres normal. Cholecystography showed gallstones and no gallbladder excretion. The pyruvate kinase activity in erythrocytes at 25° and pH 7.5 was only 9.5 and 6 μM substrate turnover/min 1011, respectively, on two occasion, whereas 2 SD of blood donors is 25.0–49.0. Corresponding activities for hexokinase, phosphofructokinase, phosphofructoaldolase, lactate dehydrogenase, glucose 6-phosphate dehydrogenase and glutathion reductase were either within or above normal range. In her crythrocytes adenosine triphosphate was low, adenosine diphosphate normal and 2,3-diphosphoglycerate high. Further studies seem to indicate that the pyruvate kinase in our patient has latered kinetic properties, an abnormal sequence of amino acids. The pyruvate kinase activity in crythrocytes from the patient's mother was low. Similar activities in crythrocytes from the patient's father and brother were at the lower limit of normal. One brother of the maternal grandmother had hemolytic anemia, thrombocytopenia and cholelithiasis, another brother had cholelithiasis and a sister had anemia. The result of further family studies will be reported.

A SCREENING METHOD FOR THE DETECTION OF ERYTHROCYTE PYRUVATE KINASE DEFICIENCY.

A screening test is described for the evaluation of erythrocyte pyruvate kinase activity. The method is based on the use of an indicator sensitive to the variations of pH induced by the enzyme reaction. The reliability and reproducibility of the test have been compared with the spectrophotometric assay, in normal subjects, in two patients affected by hemolytic anaemia due to pyruvate kinase deficiency, and in a group of heterozygous subjects with intermediate values of pyruvate kinase activity.