High sensitivity and specificity of elevated cerebrospinal fluid kappa free light chains in suspected multiple sclerosis

Cerebrospinal fluid (CSF) analysis is routinely used in the diagnostic work-up of multiple sclerosis (MS), by detecting CSF-specific oligoclonal bands (OCB). More recently, several studies have reported CSF free light chains (FLC) as an alternative. We show that absolute CSF kappa FLC concentrations were highly sensitive - more than OCB - testing and specific for clinically isolated syndrome, relapsing remitting and primary progressive MS. Measurement of kappa FLC alone was sufficient. Our results suggest that CSF kappa FLC levels measured by nephelometry, if validated in a larger series, are a preferred test to OCB analysis in the diagnostic work-up of patients suspected of having MS. (C) 2014 Elsevier B.V. All rights reserved.