Identification of interferon-beta antibodies in a reference laboratory setting: Findings for 1144 consecutive sera

Clinical studies demonstrate differences in interferon-beta (IFNβ) antibody detection frequencies among multiple sclerosis patients receiving different IFNβ products. We sought to determine if these differences are also found when IFNβ antibodies are measured in a reference laboratory, where factors normally controlled in clinical studies are unknown. Serum IFNβ binding antibodies (BAbs) were quantitated by ELISA; BAbs-positive samples were then tested in a bioassay for neutralizing antibodies (NAbs). Consistent with clinical studies, frequencies of BAbs-positive sera and NAbs-positive sera were lower in the Avonex (IFNβ-1a) treatment group than Rebif (IFNβ-1a) and Betaseron (IFNβ-1b) groups. We further identified a predictive relationship between positive BAbs levels and NAbs activity in patients treated with IFNβ-1a products, but not those treated with IFNβ-1b.