Study on discrepancy between factor X activities assayed by amidolytic method and clotting method

Abstract

The activity of factor X in the plasma of 123 patients with various diseases was measured by the clotting method and by the amidolytic method. Measurement of clotting activity of factor X was carried out by assay of the prothrombin time with factor X deficient plasma. Measurement of the amydolytic activity of factor X was made by end-point assay with S-2222 as the substrate.In 29 patients, a distinct discrepancy was observed between the clotting activity and amidolytic activity of factor X. This discrepancy was shown markedly in patients with chronic renal failure (CRF) and uncontrolled diabetes mellitus (DM). In the patients with CRF, the amidolytic activity was higher than the clotting activity of factor X. On the other hand, in the patients with DM, the clotting activity was higher than the amidolytic activity of factor X.The changes in activities of factor X by addition of each fraction of plasma from patients with CRF or DM were observed. Fraction of the patient plasma was carried out by ultrafiltration with membrane filter PM 10 and gel filtration with Bio-Gel A-15m. On the experiment by the addition of low molecular weight fraction (MW<104) and high molecular weight fraction (MW≈106) from the plasma of patient with CRF, the amidolytic activity of factor X in the control plasma of factor X deficient plasma was increased by the addition of each fraction. The clotting activity of factor X in the control plasma was decreased by the addition of middle molecular weight fraction from the plasma of patients with DM.Based on these results, it is suggested that an intensifying effect on the amidolytic activity of factor X in the plasma of patients with CRF existed in the low molecular weight fraction (MW<104) and high molecular weight fraction (MW≈106), and that the factor X in patients DM had a different charactor from that in plasma of normal subject.