Cerebrospinal fluid free light kappa and lambda chains in oligoclonal band-negative patients with suspected Multiple Sclerosis

Diana Ferraro, Alice Trovati, Roberta Bedin, Patrizia Natali, Diego Franciotta, Mario Santangelo, Valentina Camera, Francesca Vitetta, Manuela Varani, Tommaso Trenti, Matteo Gastaldi, Sara De Biasi, Milena Nasi, Marcello Pinti, Stefano Meletti, Patrizia Sola

Research output: Contribution to journalArticlepeer-review

Abstract

BACKGROUND: Cerebrospinal fluid (CSF) free light kappa chains (kappa FLC) may be a more sensitive marker of intrathecal IgG synthesis compared to oligoclonal bands (OCBs). Our aim was to retrospectively determine the additional value of the kappa and lambda index (CSF FLC/serum FLC)/(CSF albumin/serum albumin) in predicting a Multiple Sclerosis (MS) diagnosis in a group of OCB-negative patients with suspected MS.

METHODS: CSF and serum kappa and lambda FLC were tested using Freelite kit (serum) and Freelite Mx (CSF) assay in 391 OCB-negative patients with suspected/possible MS and in 54 OCB-positive MS patients.

RESULTS: CSF kappa FLC levels were below the detection limit (0.27mg/L) in 61% of patients. Using quantitative data, we found the best kappa index cut-off value for the prediction of MS to be 5.8. A kappa index ≥5.8 was present in 25% of OCB-negative MS (23/92) and in 98% of OCB-positive MS patients. Using a qualitative approach and a kappa index cut-off of 5.9, based on literature data, we likewise found that 24% of OCB-negative MS patients had a kappa index ≥5.9, compared to 5.4% of OCB-negative non-MS patients (p<0.001). No reliable data could be obtained for the lambda index: lambda FLC were below the detection limit (0.68mg/L) in 90% of CSF samples.

CONCLUSIONS: The kappa index could contribute to the identification of OCB-negative patients with a high probability of a MS diagnosis. Using more sensitive techniques might even improve the diagnostic performance of the kappa index, and better define the role of the lambda index.

Original languageEnglish
Pages (from-to)461-7
Number of pages6
JournalEuropean Journal of Neurology
Volume27
Issue number3
DOIs
Publication statusPublished - 2020

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