Abstract
The purpose of this study was to develop a quantitative method for factor II antigen in human plasma utilizing the sensitivity and precision of RIA. Factor II was isolated by chromatographic technique and shared a single band on electrophoresis. I125 tagged factor II was prepared by a standard chloramine-T oxidation and sodium metabisulfite reduction. Antigen levels were then determined by classical double antibody radioimmunoassay. A dose response curve was generated by adding known amounts of normal human plasma to human barium sulfate-absorbed oxalated plasma. A straight line relationship existed between 15 to 140% coagulant activity (CA) and 7 to 50 μg/ml antigen content. Plasma factor II antigen in 20 normals was 29.63 ± 4.6 lag/μl (mean ± S.D.). Eight patients with induced vitamin K deficiency revealed normal antigen levels (30.13) and reduced CA (20) whereas three patients with severe hepatocellular disease were found to have reduced antigen and CA levels (6.7 μg/ml and 40% activity). The use of the RIA for measuring prothrombin protein in conjunction with coagulation factor assays could have clinical application in studying the mechanism of action of vitamin K, the developmental aspects of factor II production and activation, and in understanding acquired coagulopathies.
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Lox, C., Mikel, T., Strohm, G. et al. QUANTITATION OF HUMAN PROTHROMBIN BY RADIOIMMUNO-ASSAY (RIA). Pediatr Res 11, 475 (1977). https://doi.org/10.1203/00006450-197704000-00631
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DOI: https://doi.org/10.1203/00006450-197704000-00631