Neurology Unit, Azienda Ospedaliero-Universitaria of Modena, Modena.
Department of Biomedical, Metabolic and Neurosciences, University of Modena and Reggio Emilia, Modena.
Eur J Neurol. 2020 Mar;27(3):461-467. doi: 10.1111/ene.14121. Epub 2019 Dec 2.
Cerebrospinal fluid (CSF) kappa free light chains (FLCs) may be a more sensitive marker of intrathecal immunoglobulin (Ig)G synthesis compared with oligoclonal bands (OCBs). Our aim was to retrospectively determine the additional value of the kappa and lambda index (CSF FLC/serum FLC)/(CSF albumin/serum albumin) in predicting a multiple sclerosis (MS) diagnosis in a group of OCB-negative patients with suspected MS.
The CSF and serum kappa and lambda FLCs were tested using the Freelite kit (serum) and Freelite Mx (CSF) assay (The Binding Site Group, Bimingham, UK) in 391 OCB-negative patients with suspected/possible MS and in 54 OCB-positive patients with MS.
The CSF kappa FLC levels were below the detection limit (0.27 mg/L) in 61% of patients. Using quantitative data, we found the best kappa index cut-off value for the prediction of MS to be 5.8. A kappa index ≥5.8 was present in 25% of OCB-negative MS (23/92) and in 98% of OCB-positive patients with MS. Using a qualitative approach and a kappa index cut-off of 5.9, based on literature data, we likewise found that 24% of OCB-negative patients with MS had a kappa index ≥5.9, compared with 5.4% of OCB-negative patients without MS (P < 0.001). No reliable data could be obtained for the lambda index; lambda FLCs were below the detection limit (0.68 mg/L) in 90% of CSF samples.
The kappa index could contribute to the identification of OCB-negative patients with a high probability of an MS diagnosis. Using more sensitive techniques might even improve the diagnostic performance of the kappa index and better define the role of the lambda index.
与寡克隆带（OCB）相比，脑脊液（CSF）κ游离轻链（FLC）可能是更敏感的鞘内免疫球蛋白（Ig）G 合成标志物。我们的目的是回顾性确定κ和λ指数（CSF FLC/血清 FLC）/（CSF 白蛋白/血清白蛋白）在预测一组 OCB 阴性疑似 MS 患者中的 MS 诊断中的附加价值。
使用 Freelite 试剂盒（血清）和 Freelite Mx（CSF）测定法（英国 Bimingham 的 The Binding Site Group）检测 391 例 OCB 阴性疑似/可能 MS 患者和 54 例 OCB 阳性 MS 患者的 CSF 和血清κ和λ FLC。
61%的患者 CSF κ FLC 水平低于检测下限（0.27mg/L）。使用定量数据，我们发现预测 MS 的最佳 κ 指数截断值为 5.8。25%的 OCB 阴性 MS（23/92）和 98%的 OCB 阳性 MS 患者的 κ 指数≥5.8。使用基于文献数据的定性方法和 κ 指数截断值 5.9，我们同样发现 24%的 OCB 阴性 MS 患者的 κ 指数≥5.9，而 5.4%的 OCB 阴性非 MS 患者的 κ 指数≥5.9（P<0.001）。无法获得可靠的λ指数数据；90%的 CSF 样本中 λ FLC 低于检测下限（0.68mg/L）。
κ 指数有助于确定 OCB 阴性 MS 诊断可能性高的患者。使用更敏感的技术甚至可以提高 κ 指数的诊断性能，并更好地定义 λ 指数的作用。
