title: Validation of kappa free light chains as a diagnostic biomarker in multiple sclerosis and clinically isolated syndrome: A multicenter study.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Neurology, Wilhelminenspital, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Presslauer
authors.affiliation: FH Campus Wien - University of Applied Sciences, Austria.
authors.forename: Dejan
authors.initials: D
authors.lastname: Milosavljevic
authors.affiliation: Department of Laboratory Medicine, Wilhelminenspital, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Huebl
authors.affiliation: Karl Landsteiner Institute for Neuroimmunological and Neurodegenerative Disorders, Austria.
authors.forename: Fahmy
authors.initials: F
authors.lastname: Aboulenein-Djamshidian
authors.affiliation: Department of Laboratory Medicine, SMZ-Ost Donauspital, Austria.
authors.forename: Walter
authors.initials: W
authors.lastname: Krugluger
authors.affiliation: Department of Neurology, Innsbruck Medical University, Austria.
authors.forename: Florian
authors.initials: F
authors.lastname: Deisenhammer
authors.affiliation: Department of Neurology, University Hospital Ulm, Germany.
authors.forename: Makbule
authors.initials: M
authors.lastname: Senel
authors.affiliation: Department of Neurology, University Hospital Ulm, Germany.
authors.forename: Hayrettin
authors.initials: H
authors.lastname: Tumani
authors.affiliation: Department of Neurology, Innsbruck Medical University, Austria harald.hegen@i-med.ac.at.
authors.forename: Harald
authors.initials: H
authors.lastname: Hegen
mesh_terms: D000328:Adult; D000368:Aged; D001317:Austria; D015415:Biomarkers / Q000097:blood / Q000134:cerebrospinal fluid; D003430:Cross-Sectional Studies; D003711:Demyelinating Diseases / Q000097:blood / Q000134:cerebrospinal fluid / Q000175:diagnosis* / Q000276:immunology; D005260:Female; D005858:Germany; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000097:blood / Q000134:cerebrospinal fluid*; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000097:blood / Q000134:cerebrospinal fluid / Q000175:diagnosis* / Q000276:immunology; D009391:Nephelometry and Turbidimetry; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007145:Immunoglobulin kappa-Chains
keywords: IgG index; Kappa free light chain; cerebrospinal fluid; clinically isolated syndrome; intrathecal IgG synthesis; multiple sclerosis; oligoclonal bands; serum