Enzyme-Linked Immunosorbent Assayによる第Ⅷ因子抑制物質中のIgG subclassの検討

Abstract

Semi-quantitative analysis for factor Ⅷ (F. Ⅷ)-specific IgG subclass in the plasma of hemophilia A with F. Ⅷ inhibitor was developed by enzyme-linked immunosorbent assay (ELISA) using immobilized recombinant F. Ⅷ. The bound F. Ⅷ-specific IgG subclass was detected by monoclonal anti-IgG₁, IgG₂, IgG₃ and IgG₄ antibodies followed by peroxidase conjugated goat anti-mouse IgG. Out of 82 plasma samples from 14 patients with inhibitor, 53 samples from 11 patients were positive for only IgG₄. There was no sample which was positive for only IgG₁, IgG₂ or IgG₃. Of the eleven patients with samples which were positive for only IgG₄, one patient was also positive for only IgG₁ in one sample, four patients were also positive for only IgG₂ in eight samples and one patient was positive for only IgG₃ in three samples on different dates. None of F. Ⅷ-specific IgG subclass was detected in the plasma from 27 samples of hemophilia A without inhibitor. In conclusion, the ELISA system was suitable not only for the detection of F. Ⅷ inhibitor but also for semi-quantitative estimation of changes in the plasma content of F. Ⅷ-specific IgG subclass. Furthermore, it was demonstrated that the dominant subclass among the inhibitors was IgG₄. However, other IgG subclasses were also detected in some cases.