BAb and MxA as functional biomarkers in routine clinical laboratories for the determination of anti-IFN-beta antibodies and their bioactivity levels in multiple sclerosis patients.

In MS patients under IFNβ treatment to seek alternative treatments timely is important that anti-IFNβ antibodies and/or in vivo biologic activity loss detection in these. The most common diagnostic markers used for this purpose are BAb, Nab, and MxA. In this article, we aimed to establish the availability and feasibility of the correlation between BAb and MxA gene expression (mRNA) levels using evaluation of responses to IFNβ treatment for MS patients with a routine laboratory follow-up strategy in a major Turkish MS center. Bab seropositivity was determined in blood samples of 218 MS patients treated with different IFNβ preparations and MxA mRNA levels were measured in 128 patients among the total population. BAb seropositivity ratios to im INF-β 1a, scINF-β 1a, and sc INF-β 1b were 21.4%, 28.6%, and 70.4%, respectively (total 40%), and total loss of bioactivity (MxA mRNA) were 9.3%, 9.5%, and 11.6%, respectively (total 10.2%). The correlation between high BAb titers and low MxA mRNA levels was highly significant (P = 0.00003). Our data indicate that there is a good correlation between especially high BAbs levels and diminished MxA mRNA levels.