Neurofilament light protein and glial fibrillary acidic protein as biological markers in MS

To determine if CNS-derived proteins present in the CSF of multiple sclerosis (MS) patients reflect different pathologic processes of MS and if these proteins could be useful as biologic markers of disease activity.

Concentrations of the neurofilament light protein (NFL), glial fibrillary acidic protein (GFAP), S100B, and the neuron-specific enolase protein (NSE) were determined in the CSF of 66 MS patients and 50 healthy control subjects with immunoassays.

The mean levels of the NFL were increased during all stages of MS compared with controls (p < 0.001), peaking almost 10 times higher during acute relapses. The highest levels of GFAP were found during the secondary progressive course (p < 0.001) with a strong correlation with neurologic deficits (Expanded Disability Status Scale score, r = 0.73, p < 0.001). No increase of S100B or NSE protein was found in the CSF of MS patients compared with control subjects.

Increased level of NFL is a general feature of MS, indicating continuous axonal damage during the entire course of the disease with the most profound damage during acute relapses. GFAP may serve as a biomarker for disease progression, probably reflecting the increasing rate of astrogliosis.