Free light chains in cerebrospinal fluid of multiple sclerosis patients negative for IgGoligoclonal bands

Abstract The detection of IgG oligoclonal bands (OCBs) in cerebrospinal fluid (CSF) is, as yet, the recommended biochemical marker for the diagnosis of multiple sclerosis (MS). Aim of this study was to investigate the behaviour of free light chains (FLC) in OCBs negative (OCBs-) MS patients compared with that in OCBs positive (OCBs+) MS patients and in a control group (CG) of subjects without cerebrospinal inflammatory disease. At multiple comparisons between the three groups, statistically significant differences ( p 50% of MS OCBs- subjects studied evidenced the same values ofκFLC, QκFLC and κFLC index found in CG.. Conversely, if the aim is to select MS subjects while avoiding undertaking the more complex isoelectrofocusing test, values with absolute specificity for MS(QκFLC = 15, sensitivity = 0.76 and κFLCindex = 3.09, sensitivity = 0.72) could be used. The values found in this study call for confirmation with data from more subjects, including those with other CSF inflammatory diseases. Anyway, the most important finding was that, for some OCBs- subjects, κFLC, are more effective than OCBs in diagnosing MS.