Evaluation of a multiplex bead-based screening assay for detection of binding antibodies to interferon-beta.

Multiple sclerosis patients treated with interferon-beta (IFNbeta) can develop neutralizing binding antibodies (BAbs) that reduce the agent's effectiveness. Screening for these antibodies can be performed by ELISA. We investigated a multianalyte immune detection (MAID) assay as an alternative to ELISA to detect anti-IFNbeta-1a and -1b. For 146 sera representing both 1a and 1b treated groups, MAID concordance with ELISA was 94% and 92%, respectively. For all discordant results, the corresponding ELISA and MAID values were within 4 units of each other, and all discordant values but one fell within 2 units of the BAbs cutoff value for reflexing to neutralization testing (4 units). Our data indicate that the MAID assay is an accurate and cost-effective alternative to ELISA for detecting BAbs to IFNbeta.