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Simplified immunoradiometric assay for factor VIII coagulant antigen
Author(s) -
Thomas K. B.,
Howard M. A.,
Koutts J.,
Firkin B. G.
Publication year - 1982
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1982.tb07288.x
Subject(s) - immunoradiometric assay , medicine , antigen , immunology , radioimmunoassay
A simplified, non‐competitive, solid phase immunoradiometric assay has been developed for the quantitation of factor VIII coagulant antigen (VIII:CAg)—the antigenic counterpart of FVIII coagulant activity (VIII:C). Both homologous and heterologous antibodies to human factor VIII (FVIII) were used in this assay. Initially, FVIII in a test sample was attached to immobilized, human IgG obtained from a polytransfused haemophilia A patient with a high titre antibody to VIII:C. The bound FVIII was then detected using rabbit 125 I‐IgG specific for human FVIII. The concentration of VIII:CAg correlated well with VIII:C levels in the plasma from normal donors ( r = 0.84, n = 15). Homozygote von Willebrand's disease patients had undetectable levels of VIII:CAg in their plasma. Patients with severe haemophilia A (VIII:C < 0.01 u/ml) could be divided into groups on the basis of the VIII:CAg levels, i.e. those having undetectable VIII:CAg and others with measurable VIII:CAg. VIII:CAg detected in normal serum was < 0.002 u/ml. In this assay the use of human antibody to FVIII is considerably decreased compared to other methods for VIII:CAg, and the time‐consuming steps to immunopurify human anti‐FVIII antibody are eliminated.