ObjectiveTo determine what kappa free light chain (KFLC) metric has the highest capacity to separate healthy patients from patients with MS, we evaluated the sensitivity, specificity, and the overall diagnostic accuracy of 4 different KFLC metrics. To assess the usefulness of KFLC in the diagnostics of MS, we compared the different KFLC metrics with oligoclonal bands (OCBs), the current gold standard biochemical method to demonstrate intrathecal antibody production.MethodsCSF and plasma were collected from patients with confirmed or suspected MS, other neurological diseases, as well as symptomatic and healthy controls between May 2017 and May 2018 (n = 335) at the Department of Neurology, Karolinska University Hospital, as part of routine diagnostic workup. KFLC analysis and isoelectric focusing for the detection of oligoclonal bands (OCB) were determined and correlated with diagnosis. Receiver operating characteristic (ROC) curve analysis was used to determine accuracy.ResultsOCBs yielded a sensitivity of 87% and a specificity of 100%. All KFLC metrics showed a high sensitivity (89%–95%) and specificity (95%–100%). Using the optimal cutoff according to the Youden Index resulted for the KFLC intrathecal fraction in a cutoff of −0.41 with a sensitivity of 95% and a specificity of 97% and for CSF KFLC/CSF albumin with a cutoff of 1.93 × 10−3 with a sensitivity of 94% and specificity of 100%.ConclusionAll evaluated KFLC metrics have excellent accuracy, and both KFLC intrathecal fraction and CSF KFLC/CSF albumin are at least as good as OCB in separating patients with MS from a control group.Classification of evidenceThis study provides Class III evidence that CSF KFLC accurately distinguishes patients with MS from healthy controls.

INTRODUCTION:There is an urgent need for novel blood biomarkers for the detection of Alzheimer's disease (AD). We previously showed that levels of the bisecting N-acetylglucosamine glycan epitope was elevated in cerebrospinal fluid in AD.However, its diagnostic value in blood is unknown. METHODS:We analyzed blood levels of bisecting N-acetylglucosamine and total tau in a retrospective cohort of 233 individuals. Progression to AD was compared between the groups using Cox regression. The predictive value of the biomarkers was determined by logistic regression. RESULTS:Bisecting N-acetylglucosamine correlated with tau levels (p < 0.0001). Individuals with an intermediate tau/bisecting N-acetylglucosamine ratio had elevated AD risk (hazard ratio = 2.06, 95% confidence interval [CI]: 1.18-3.6). Moreover, a combined model including tau/bisecting N-acetylglucosamine ratio, apolipoprotein E (APOE) ε4 status, and Mini-Mental State Examination score predicted future AD (area under the curve = 0.81, 95% CI: 0.68-0.93).

Idiopathic normal pressure hydrocephalus (iNPH) is the most common form of hydrocephalus in the adult population, and is often treated with cerebrospinal fluid (CSF) drainage using a ventriculoperitoneal (VP) shunt. Symptoms of iNPH include gait impairment, cognitive decline, and urinary incontinence. The pathophysiology behind the symptoms of iNPH is still unknown, and no reliable biomarkers have been established to date. The aim of this study was to investigate the possible use of the oxysterols as biomarkers in this disease. CSF levels of the oxysterols 24S- and 27-hydroxycholesterol, as well as the major metabolite of 27-hydroxycholesterol, 7 alpha hydroxy-3-oxo-4-cholestenoic acid (7HOCA), were measured in iNPH-patients before and after treatment with a VP-shunt. Corresponding measurements were also performed in healthy controls. VP-shunt treatment significantly increased the levels of 7HOCA and 24S-hydroxycholesterol in CSF (p = 0.014 and p = 0.037, respectively). The results are discussed in relation to the beneficial effects of VP-shunt treatment. Furthermore, the possibility that CSF drainage may reduce an inhibitory effect of transiently increased pressure on the metabolic capacity of neuronal cells in the brain is discussed. This capacity includes the elimination of cholesterol by the 24S-hydroxylase mechanisms.