title: Sensitive solid phase enzyme immunoassay for factor IX antigen and classification of hemophilia B.
abstract: A sensitive solid phase enzyme immunoassay (EIA) was developed for the measurement of factor IX antigen (IX:AG), using rabbit antihuman factor IX antiserum and beta-D-galactosidase, which enabled us to detect IX:AG as low as 10(-4)U/ml. 37 patients with severe hemophilia B have been investigated by EIA, inhibitor neutralization assay and bovine brain prothrombin time. They could be divided into four genetic variants. 25% had normal levels of IX:AG but decreased levels of factor IX clotting activity. On crossed immunoelectrophoresis of the hemophilia B+ and hemophilia BM, we could not find abnormalities in electrophoretic mobilities compared to normal subjects in the presence of 1 mM Ca++ lactate.
mesh_terms: D000941:Antigens / Q000032:analysis*; D005164:Factor IX / Q000276:immunology*; D002836:Hemophilia B / Q000145:classification / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007123:Immunoelectrophoresis, Two-Dimensional; D007124:Immunoenzyme Techniques; D008297:Male
chemical_list: D000941:Antigens; D005164:Factor IX