Serum and cerebrospinal fluid light neurofilaments and antibodies against them in clinically isolated syndrome and multiple sclerosis.

A release of light neurofilament subunits (NFL) into cerebrospinal fluid (CSF) and serum in multiple sclerosis (MS) may induce an immune response. We examined CSF and serum NFL levels and IgG antibodies against NFL in 19 patients with a clinically isolated syndrome (CIS) early converted into MS, 20 CIS-non-converters, 23 MS patients and 32 controls. CSF NFL levels were significantly higher in all patient groups. The highest CSF or intrathecally (IT) synthesized anti-NFL antibodies and CSF/serum ratios of anti-NFL antibodies were observed in CIS-converters. CSF NFL and CSF or IT anti-NFL antibodies could be surrogate biomarkers of axonal injury in early MS.