Factor VIII clotting antigen (VIIICAg) in haemophilia measured by two immunoradiometric assays (IRMA) using different antibodies, and the measurement of inhibitors to procoagulant factor VIII (VIIIC) by IRMA. 1981

R A Furlong, and I R Peake, and A L Bloom

Factor VIII clotting antigen (VIIICAg) was measured by immunoradiometric assay (IRMA) using two different antibodies. Both antibodies arose in polytransfused severe haemophiliacs and had similar titres against VIIIC. In 12 normal plasmas there was no significant difference in VIIICAg values obtained (VIIICAg (AbI) = VIIICAg (AbII)). In the majority of 15 severe haemophiliacs tested VIIICAg was undetectable by both antibodies. In 28 mild to moderate haemophiliacs VIIICAg (AbII) was significantly greater than VIIICAg (AbI) (P less than 0.01) suggesting different antigenic determinants. The difference, however, was small and does not affect diagnosis of haemophilia. A modified IRMA has been used to measure anti VIIIC inhibitors by competition of the inhibitor with 125I labelled VIIICAg antibodies for common antigenic determinants. Using an inhibitor of 225 Bethesda units as a standard, results by IRMA of inhibitors in severe haemophiliacs have been similar to those obtained by clotting assay, but with a sensitivity of 0.01 u/ml suggesting the possible use in the detection of weak inhibitors.

UI MeSH Term Description Entries
D011863 Radioimmunoassay Classic quantitative assay for detection of antigen-antibody reactions using a radioactively labeled substance (radioligand) either directly or indirectly to measure the binding of the unlabeled substance to a specific antibody or other receptor system. Non-immunogenic substances (e.g., haptens) can be measured if coupled to larger carrier proteins (e.g., bovine gamma-globulin or human serum albumin) capable of inducing antibody formation. Radioimmunoassays
D005169 Factor VIII Factor VIII of blood coagulation. Antihemophilic factor that is part of the factor VIII/von Willebrand factor complex. Factor VIII is produced in the liver and acts in the intrinsic pathway of blood coagulation. It serves as a cofactor in factor X activation and this action is markedly enhanced by small amounts of thrombin. Coagulation Factor VIII,Factor VIII Clotting Antigen,Factor VIII Coagulant Antigen,Factor VIII Procoagulant Activity,Thromboplastinogen,Blood Coagulation Factor VIII,F VIII-C,Factor 8,Factor 8 C,Factor Eight,Factor VIIIC,Hyate-C,Hyatt-C,F VIII C,Hyate C,HyateC,Hyatt C,HyattC
D006467 Hemophilia A The classic hemophilia resulting from a deficiency of factor VIII. It is an inherited disorder of blood coagulation characterized by a permanent tendency to hemorrhage. Factor VIII Deficiency,Hemophilia,Autosomal Hemophilia A,Classic Hemophilia,Deficiency, Factor VIII,Factor 8 Deficiency, Congenital,Factor VIII Deficiency, Congenital,Haemophilia,Hemophilia A, Congenital,Hemophilia, Classic,As, Autosomal Hemophilia,Autosomal Hemophilia As,Classic Hemophilias,Congenital Hemophilia A,Congenital Hemophilia As,Hemophilia A, Autosomal,Hemophilia As,Hemophilia As, Autosomal,Hemophilia As, Congenital,Hemophilias, Classic
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000906 Antibodies Immunoglobulin molecules having a specific amino acid sequence by virtue of which they interact only with the ANTIGEN (or a very similar shape) that induced their synthesis in cells of the lymphoid series (especially PLASMA CELLS).
D000941 Antigens Substances that are recognized by the immune system and induce an immune reaction. Antigen
D001667 Binding, Competitive The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements. Competitive Binding

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