Crespi Ilaria, Vecchio Domizia, Serino Roberto, Saliva Elena, Virgilio Eleonora, Sulas Maria Giovanna, Bellomo Giorgio, Dianzani Umberto, Cantello Roberto, Comi Cristoforo
Laboratory of Clinical Biochemistry, Department of Health Sciences, AOU Maggiore della Carità, University ofPiemonte Orientale, corso Mazzini 18, 28100 Novara, Italy.
Institute of Neurology, Department of Transational Medicine, AOU Maggiore della Carità, University of PiemonteOrientale, corso Mazzini 18, 28100 Novara, Italy.
J Clin Med. 2019 Apr 2;8(4):446. doi: 10.3390/jcm8040446.
The K free light chain (K) index has been suggested as a reliable marker of intrathecal synthesis,despite the 2017 McDonald criteria for multiple sclerosis (MS) suggesting to "interpret with caution positiveimmunoglobulin G (IgG) index when testing for oligoclonal bands (OB) is negative or not performed". Theaim of this study was to compare the performance of K and IgG indexes for MS diagnosis and OB detectionin a cohort of Italian patients. We enrolled 385 patients (127 MS, 258 non-MS) who had cerebrospinal fluid(CSF) analysis, including isoelectric focusing (IEF), to detect OB in the diagnostic work-up. Albumin, IgGand free light chains were measured by nephelometry and used to calculate IgG and K indexes. Althoughthe two markers were highly related (r = 0.75, r2 = 0.55, p < 0.0001), the K index showed greater sensitivity andnegative predictive value (versus the IgG index) for OB detection (97% versus 48% and 97% versus 71%) andMS diagnosis (96% versus 50% and 98% versus 78%). These results support K index (and not IgG index) as afirst-line marker for MS, followed by IEF, according to a sequential testing approach in CSF analysis.
尽管2017年多发性硬化症（MS）的麦克唐纳标准建议“当寡克隆带（OB）检测为阴性或未进行时，对阳性免疫球蛋白G（IgG）指数要谨慎解释”，但游离κ轻链（κ）指数已被认为是鞘内合成的可靠标志物。本研究的目的是比较κ指数和IgG指数在一组意大利患者中用于MS诊断和OB检测的性能。我们纳入了385例患者（127例MS患者，258例非MS患者），这些患者在诊断检查中进行了脑脊液（CSF）分析，包括等电聚焦（IEF）以检测OB。通过散射比浊法测量白蛋白、IgG和游离轻链，并用于计算IgG和κ指数。尽管这两种标志物高度相关（r = 0.75，r² = 0.55，p < 0.0001），但κ指数在OB检测（97%对48%，97%对71%）和MS诊断（96%对50%，98%对78%）方面显示出更高的敏感性和阴性预测值（与IgG指数相比）。根据CSF分析中的序贯检测方法，这些结果支持将κ指数（而非IgG指数）作为MS的一线标志物，其次是IEF。
