Heterogeneity of haemophilia A: a study with three different antisera

Abstract

One human and 1 rabbit antibody againist VIII:C [coagulant factor VIII] in a fluid-phase, inhibitor neutralization assay (INA) and 1 human antibody in a solid-phase, and immunoradiometric assay (IRMA) were used to investigate a group of 59 patients with severe, moderate and mild hemophilia A. Patients were classified as hemophilia A+ when the VIII:C/VIIICAG [factor VIII:C-related antigen] ratio was less than 0.4 while the absolute VIIICAG value exceeded 0.25 U/ml. Three hemophiliacs (from 2 pedigrees) were classified as A+ in all 3 assay systems. Fifty percent of the patients were classified as hemophilia A+ on the basis of at least 1 assay. The other 50%, including 66% of the patients with severe hemophilia, were shown to be A- by all 3 assay systems. Combining the data obtained with the 3 different antibodies, 4 different categories could be distinguished, in addition to the classification based on severity.