Free kappa light chains in cerebrospinal fluid as a biomarker to assess risk conversion to multiple sclerosis

Background: Multiple sclerosis (MS) initiates with a first attack or clinically isolated syndrome (CIS). The importance of an early treatment in MS leads to the search, as soon as possible, for novel biomarkers which can predict conversion from CIS to MS. Objective: The purpose of this study was to assess the predictive value of the kappa index (� index), using kappa free light light chains (� FLCs) in cerebrospinal fluid (CSF), for the conversion of CIS patients to MS, and compare its accuracy with other parameters used in clinical practice. Methods: FLC levels were analysed in CSF from 176 patients: 70 as control group, 77 CIS, and 29 relapsingremitting MS. FLC levels were quantified by nephelometry. Results: � Index sensitivity and specificity (93.1%; 95.7%) was higher than those from the immunoglobulin G (IgG) index (75.9%; 94.3%), and lower than those from oligoclonal IgG bands (OCGBs)