1. Free light chains in the cerebrospinal fluid. Comparison of different methods to determine intrathecal synthesis.
- Author
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Hegen H, Walde J, Milosavljevic D, Aboulenein-Djamshidian F, Senel M, Tumani H, Deisenhammer F, and Presslauer S
- Subjects
- Adult, Austria, Cross-Sectional Studies, Demyelinating Diseases immunology, Diagnostic Tests, Routine methods, Female, Germany, Humans, Immunoglobulin Isotypes analysis, Immunoglobulin Isotypes blood, Immunoglobulin Isotypes cerebrospinal fluid, Immunoglobulin Light Chains blood, Immunoglobulin kappa-Chains blood, Immunoglobulin lambda-Chains blood, Immunoglobulins cerebrospinal fluid, Male, Middle Aged, Multiple Sclerosis immunology, Nervous System Diseases immunology, ROC Curve, Immunoglobulin Light Chains analysis, Immunoglobulin Light Chains cerebrospinal fluid, Immunoglobulins analysis
- Abstract
Background Free light chains (FLC) have been proposed as diagnostic biomarkers in the cerebrospinal fluid (CSF) of patients with inflammatory central nervous system (CNS) diseases. However, which method to use for determining an intrathecal FLC synthesis has not yet been clarified. The objective of this study was to compare the diagnostic performance of CSF FLC concentration, FLC quotient (QFLC), FLC index and FLC intrathecal fraction (FLCIF). Methods κ- and λ-FLC were measured by nephelometry under blinded conditions in CSF and serum sample pairs of patients with clinically isolated syndrome (CIS; n = 60), multiple sclerosis (MS; n = 60) and other neurological diseases (n = 60) from four different MS centers. QFLC was calculated as the ratio of CSF/serum FLC concentration, the FLC index as QFLC/albumin quotient and the percentage FLCIF by comparing QFLC to a previously empirically determined, albumin quotient-dependent reference limit. Results CSF FLC concentration, QFLC, FLC index and FLCIF of both the κ- and λ-isotype were significantly higher in patients with CIS and MS than in the control group, as well as in oligoclonal bands (OCB) positive than in OCB negative patients. Each parameter was able to identify MS/CIS patients and OCB positivity, however, diagnostic performance determined by receiver operating characteristic (ROC) analyses differed and revealed superiority of FLC index and FLCIF. Conclusions These findings support the diagnostic value of FLC measures that correct for serum FLC levels and albumin quotient, i.e. blood-CSF barrier function.
- Published
- 2019
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