{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,5]],"date-time":"2026-05-05T12:29:41Z","timestamp":1777984181511,"version":"3.51.4"},"reference-count":31,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2026,4,1]],"date-time":"2026-04-01T00:00:00Z","timestamp":1775001600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,4,1]],"date-time":"2026-04-01T00:00:00Z","timestamp":1775001600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Journal of Neurochemistry"],"published-print":{"date-parts":[[2026,4]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    The kappa free light chain (KFLC) index is a promising biomarker for detecting intrathecal immunoglobulin synthesis in multiple sclerosis (MS), offering a quantitative and automated alternative to oligoclonal bands (OCBs). However, its use in clinical practice is limited by heterogeneous thresholds and a lack of standardized diagnostic algorithms. Objective to develop and validate a biological diagnostic algorithm for MS that fully integrates the KFLC\u2010index alongside current recommended CSF biomarkers, particularly CSF\u2010restricted OCBs. We conducted a prospective, monocentric study including 198 patients undergoing lumbar puncture for suspected neurological disease. Patients were classified as having MS (including CIS\/RIS) or non\u2010inflammatory neurological disorders. Paired cerebrospinal fluid and serum KFLC and LFLC were quantified using a turbidimetric assay (Optilite, The Binding Site). Diagnostic performance was assessed by ROC analysis. A diagnostic algorithm was developed and validated in an independent cohort. In the derivation cohort (\n                    <jats:italic>n<\/jats:italic>\n                    \u2009=\u200980), the KFLC\u2010index showed excellent accuracy (AUC\u2009=\u20090.93). An optimal threshold of 20.27 provided 80.6% sensitivity and 100% specificity. A lower threshold of 3 increased sensitivity (96.8%) but reduced specificity (26.5%). Application of the diagnostic algorithm to the replication cohort (\n                    <jats:italic>n<\/jats:italic>\n                    \u2009=\u200970) confirmed the absence of false positive and false negative results for threshold values. Systematic OCBs testing enhanced interpretation in intermediate KFLC\u2010index ranges (3\u201320). The algorithm's performance was consistent with previously published thresholds. The KFLC\u2010index is a robust biomarker for MS diagnosis. Integration into a tiered algorithm offers excellent diagnostic performance, though local validation remains essential before broad clinical adoption.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:boxed-text content-type=\"graphic\" position=\"anchor\">\n                      <jats:graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" mimetype=\"image\/png\" position=\"anchor\" specific-use=\"enlarged-web-image\" xlink:href=\"graphic\/jnc70423-gra-0001-m.png\">\n                        <jats:alt-text>image<\/jats:alt-text>\n                      <\/jats:graphic>\n                    <\/jats:boxed-text>\n                  <\/jats:p>","DOI":"10.1111\/jnc.70423","type":"journal-article","created":{"date-parts":[[2026,4,1]],"date-time":"2026-04-01T09:16:11Z","timestamp":1775034971000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["The Kappa Free Light Chains Index in Multiple Sclerosis: From Emerging Evidence to Clinical Application"],"prefix":"10.1111","volume":"170","author":[{"given":"No\u00e9","family":"Verchere","sequence":"first","affiliation":[{"name":"Biochemistry Laboratory CHU Pontchaillou  Rennes France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"S\u00e9gol\u00e8ne","family":"Roult","sequence":"additional","affiliation":[{"name":"Biochemistry Laboratory CHU Pontchaillou  Rennes France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Laure","family":"Michel","sequence":"additional","affiliation":[{"name":"Neurology CHU Pontchaillou  Rennes France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Emmanuelle","family":"Le Page","sequence":"additional","affiliation":[{"name":"Neurology CHU Pontchaillou  Rennes France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chlo\u00e9","family":"Rousseau","sequence":"additional","affiliation":[{"name":"Biostatistics CHU Pontchaillou  Rennes 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France"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Caroline","family":"Moreau","sequence":"additional","affiliation":[{"name":"Biochemistry Laboratory CHU Pontchaillou  Rennes France"},{"name":"Univ Rennes, CHU Rennes, INSERM, EHESP, IRSET (Institut de Recherche en Sant\u00e9, Environnement et Travail) UMR_S 1085  Rennes France"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2026,4,1]]},"reference":[{"key":"e_1_2_10_2_1","first-page":"402","article-title":"Clinical Use of \u03ba Free Light Chains Index as a Screening Test for Multiple Sclerosis","volume":"51","author":"Agnello L.","year":"2020","journal-title":"Laboratoriums 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