A Role for Cerebrospinal Fluid Kappa Free Light Chains in Diagnosing Multiple Sclerosis?

In addition to immunoglobulin G (IgG), plasma cells secrete kappa free light chains (KFLCs). To study the potential usefulness of KFLCs in diagnosing multiple sclerosis (MS), investigators evaluated patients with clinically isolated syndrome (CIS) and positive cerebrospinal fluid (CSF) according to varying cutoff levels of KFLC indices.

Of 214 patients with CIS, 64.5% were positive for oligoclonal bands (OCBs), 63.6% for KFLC-5.9, 63.1% for KFLC-6.6, and 58.9% for KFLC-10.6. For those who met criteria for dissemination in space, KFLC-5.9 increased MS diagnosis by 5.1%, KFLC-6.6 by 4.7%, and KFLC-10.61 by 4.2%. KFLC-5.9 and 6.6 had comparable sensitivity and specificity to OCBs for MRI dissemination in space and time in the next 5 years.