Impact of complement activation on clinical outcomes in multiple sclerosis.

We determined activation profiles of the classical and alternative complement pathway in 39 treatment-naïve patients with early relapse-onset MS. Plasma concentrations of complement fragments were unchanged in MS compared to 32 patients with non-inflammatory neurological diseases. Profiles in patients experiencing clinical exacerbations did not differ from patients with stable disease and did not correlate with baseline EDSS, numbers of T2 lesions and time to second relapse. Long-term EDSS outcomes 4 years after diagnosis did not significantly correlate with baseline complement levels. These data do not support the use of complement activation products as biomarkers for disease activity in early MS.