Validation of kappa free light chains as a diagnostic biomarker in multiple sclerosis and clinically isolated syndrome: A multicenter study. Mult Scler. 2015. pii: 1352458515594044. [Epub ahead of print]
BACKGROUND:Kappa free light chains (KFLCs) have been proposed as a diagnostic biomarker in patients with clinically isolated syndrome (CIS) and multiple sclerosis (MS).
OBJECTIVE:The objective of this paper is to validate the diagnostic accuracy of intrathecal KFLC synthesis in a multicenter study.
METHODS:KFLCs were measured by nephelometry under blinded conditions in cerebrospinal fluid (CSF) and serum sample pairs of patients with CIS (n = 60), MS (n = 60) and other neurological diseases (n = 60) from four different MS centers. The upper normal limit for intrathecal KFLC concentrations depending on blood-CSF barrier function was previously calculated in a cohort of 420 control patients.
RESULTS:Diagnostic sensitivity of intrathecal KFLC synthesis, IgG synthesis according to Reiber, IgG index and oligoclonal bands (OCBs) was 95%, 72%, 73% and 93% in patients with MS and 82%, 47%, 43% and 72% in patients with CIS. Specificity of intrathecal KFLC synthesis was 95% and 98% for all other measures.
CONCLUSION:These findings further support the diagnostic value of intrathecal KFLC synthesis in CIS and MS patients and demonstrate a valid, easier and rater-independent alternative to OCB detection.