Comparison of three PCR assays for the evaluation of interferon-beta biological activity in patients with multiple sclerosis.

Background: The gene expression of the myxovirus-resistant protein A (MxA) gene is a sensitive measure of the biological response of therapeutically applied interferon-beta (IFNbeta) and of its reduced bioavailability due to inhibiting factors such as IFNbeta-induced neutralizing antibodies (NAbs).

Methods: We compared three methods for MxA mRNA quantification in 826 peripheral blood mononuclear cell (PBMC) samples obtained from patients with multiple sclerosis (MS). MxA mRNA measurements were performed using quantitative-competitive (qc)-PCR, real time-PCR, and the new semi-quantitative (sq)-PCR assay (MxA IBRIDOGEN).