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

ABSTRACT

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 ([Formula see text] index), using kappa free light light chains ([Formula see text]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 relapsing-remitting MS. FLC levels were quantified by nephelometry. RESULTS: [Formula see text] 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) (96.5%; 98.6%). The optimal cut-off for [Formula see text] index was 10.62. Most of the CIS patients with [Formula see text] index >10.62 presented OCGBs, IgG index >0.56 and fulfilled magnetic resonance imaging (MRI) criteria. CONCLUSION: CIS patients above [Formula see text] index cut-off of 10.62 present 7.34-fold risk of conversion to MS than CIS below this value. The [Formula see text] index correlated with positive OCGBs, IgG index above 0.56 and MRI criteria.