Kappa free light chains is a valid tool in the diagnostics of MS: A large multicenter study

C. E. Leurs, H. A. M. Twaalfhoven, B. I. Lissenberg-Witte, V. van Pesch, I. Dujmovic, J. Drulovic, M. Castellazzi, T. Bellini, M. Pugliatti, J. Kuhle, L. M. Villar, J. C. Alvarez-Cermeño, R. Alvarez-Lafuente, H. Hegen, F. Deisenhammer, L. M. Walchhofer, E. Thouvenot, M. Comabella, X. Montalban, L. VécseiC. Rajda, D. Galimberti, E. Scarpini, A. Altintas, K. Rejdak, J. L. Frederiksen, G. Pihl-Jensen, P. E. H. Jensen, M. Khalil, M. M. Voortman, F. Fazekas, A. Saiz, D. la Puma, M. Vercammen, L. Vanopdenbosch, B. M. J. Uitdehaag, J. Killestein, C. Bridel, C. Teunissen

Research output: Contribution to journalArticleAcademicpeer-review

54 Citations (Scopus)


Objective: To validate kappa free light chain (KFLC) and lambda free light chain (LFLC) indices as a diagnostic biomarker in multiple sclerosis (MS). Methods: We performed a multicenter study including 745 patients from 18 centers (219 controls and 526 clinically isolated syndrome (CIS)/MS patients) with a known oligoclonal IgG band (OCB) status. KFLC and LFLC were measured in paired cerebrospinal fluid (CSF) and serum samples. Gaussian mixture modeling was used to define a cut-off for KFLC and LFLC indexes. Results: The cut-off for the KFLC index was 6.6 (95% confidence interval (CI) = 5.2–138.1). The cut-off for the LFLC index was 6.9 (95% CI = 4.5–22.2). For CIS/MS patients, sensitivity of the KFLC index (0.88; 95% CI = 0.85–0.90) was higher than OCB (0.82; 95%CI = 0.79–0.85; p < 0.001), but specificity (0.83; 95% CI = 0.78–0.88) was lower (OCB = 0.92; 95% CI = 0.89–0.96; p < 0.001). Both sensitivity and specificity for the LFLC index were lower than OCB. Conclusion: Compared with OCB, the KFLC index is more sensitive but less specific for diagnosing CIS/MS. Lacking an elevated KFLC index is more powerful for excluding MS compared with OCB but the latter is more important for ruling in a diagnosis of CIS/MS.

Original languageEnglish
Pages (from-to)912-923
Number of pages12
Issue number8
Early online date8 May 2019
Publication statusPublished - 1 Jul 2020


  • CSF
  • KFLC
  • Multiple sclerosis
  • OCB
  • biomarkers

Cite this