{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,3]],"date-time":"2026-10-03T10:01:51Z","timestamp":1791021711633,"version":"4.1.0"},"reference-count":25,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2026,4,17]],"date-time":"2026-04-17T00:00:00Z","timestamp":1776384000000},"content-version":"vor","delay-in-days":16,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/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"}],"funder":[{"DOI":"10.13039\/100018367","name":"Swedish Foundation for MS Research","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100018367","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100005689","name":"G\u00f6teborgs L\u00e4kares\u00e4llskap","doi-asserted-by":"publisher","award":["GLS #x2010;1021566"],"award-info":[{"award-number":["GLS #x2010;1021566"]}],"id":[{"id":"10.13039\/501100005689","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Euro J of Neurology"],"published-print":{"date-parts":[[2026,4]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Cerebrospinal fluid (CSF) kappa free light chains (KFLC) is a sensitive marker of intrathecal immunoglobulin synthesis and is incorporated into the 2024 McDonald criteria for multiple sclerosis (MS). How disease\u2010modifying therapies (DMTs) influence KFLC dynamics and their association with treatment response remains unclear.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>To determine whether intrathecal KFLC synthesis changes during DMT and whether these changes are associated with clinical outcomes.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>\n                      Patients with treatment\u2010na\u00efve relapsing\u2013remitting MS were prospectively enrolled at the Sahlgrenska MS Center (Gothenburg, Sweden). Paired CSF and serum samples were collected at baseline and after 12\u2009months of treatment with dimethyl fumarate (DMF) or natalizumab (NTZ). KFLC index was calculated as [(CSF KFLC\/serum KFLC)\/(CSF albumin\/serum albumin)]. Treatment response was assessed using no evidence of disease activity\u20103 (NEDA\u20103) and progression independent of relapse and MRI activity (PIRMA\n                      <jats:sup>+<\/jats:sup>\n                      ).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Forty\u2010eight patients were included (DMF\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u200926, NTZ\n                      <jats:italic>n<\/jats:italic>\n                      \u2009=\u200922). NTZ reduced KFLC index from a median 117.4 (63.6\u2013171.9) at baseline to 78.8 (39.4\u2013104.0) at 12\u2009months (adjusted\n                      <jats:italic>p<\/jats:italic>\n                      \u2009=\u20090.003), corresponding to a median decline of \u221251.0 (IQR \u221282.1 to \u221224.7), whereas DMF produced no meaningful change. In NTZ\u2010treated patients maintaining NEDA\u20103 or without PIRMA\n                      <jats:sup>+<\/jats:sup>\n                      , KFLC index declined markedly (both\n                      <jats:italic>p<\/jats:italic>\n                      \u2009&lt;\u20090.01). Change in KFLC index predicted outcomes, yielding an AUC of 1.0 for NEDA\u20103 and 0.79 for non\u2010PIRMA\n                      <jats:sup>+<\/jats:sup>\n                      .\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>Natalizumab appears to reduce intrathecal KFLC synthesis, and a decline in KFLC index may reflect effective suppression of CNS humoral immunity. \u0394KFLC index could serve as a sensitive biomarker of treatment response and disease stability in MS.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1111\/ene.70602","type":"journal-article","created":{"date-parts":[[2026,4,17]],"date-time":"2026-04-17T13:43:03Z","timestamp":1776433383000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Kappa Free Light Chains Reflect Treatment Response and Progression Independent of Focal Inflammation in Multiple Sclerosis"],"prefix":"10.1111","volume":"33","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-5078-9690","authenticated-orcid":false,"given":"Igal","family":"Rosenstein","sequence":"first","affiliation":[{"name":"Department of Clinical Neuroscience Institute of Neuroscience and Physiology at Sahlgrenska Academy, University of Gothenburg  Gothenburg Sweden"},{"name":"Region V\u00e4stra G\u00f6taland Sahlgrenska University Hospital, Department of Neurology  Gothenburg Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Markus","family":"Axelsson","sequence":"additional","affiliation":[{"name":"Department of Clinical Neuroscience Institute of Neuroscience and Physiology at Sahlgrenska Academy, University of Gothenburg  Gothenburg Sweden"},{"name":"Region V\u00e4stra G\u00f6taland Sahlgrenska University Hospital, Department of Neurology  Gothenburg Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7151-201X","authenticated-orcid":false,"given":"Magnus","family":"Johnsson","sequence":"additional","affiliation":[{"name":"Department of Clinical Neuroscience Institute of Neuroscience and Physiology at Sahlgrenska Academy, University of Gothenburg  Gothenburg Sweden"},{"name":"Region V\u00e4stra G\u00f6taland Sahlgrenska University Hospital, Department of Neurology  Gothenburg Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2477-0088","authenticated-orcid":false,"given":"Clas","family":"Malmestr\u00f6m","sequence":"additional","affiliation":[{"name":"Department of Clinical Neuroscience Institute of Neuroscience and Physiology at Sahlgrenska Academy, University of Gothenburg  Gothenburg Sweden"},{"name":"Region V\u00e4stra G\u00f6taland Sahlgrenska University Hospital, Department of Neurology  Gothenburg 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