Clin Chem Lab Med. 2013 Dec;51(12):2303-10. doi: 10.1515/cclm-2013-0361.
We compared a novel assay for free light chain (FLC) quantitation based on monoclonal antibodies (N-Latex, Siemens, Germany) to the established polyclonal antibody-based assay (Freelite™, The Binding Site, UK) in AL amyloidosis.
Sixty-two diagnostic samples were analysed on a BNII nephelometer, 32 of which also had a post-treatment sample.
In the diagnostic samples: for AL of κ type, the median involved FLC (iFLC) was significantly lower by the N-Latex assay (289 vs. 667 mg/L, p=0.0002) whereas for λ AL the values were similar (148 vs. 161 mg/L, p=0.84). Measurable disease, defined as a difference between involved and uninvolved FLC (dFLC) >50 mg/L was present in 82% by the N-Latex assay compared to 89% by the Freelite™ assay. For diagnostic sensitivity, the FLC ratio was normal in 21% (95% CI 12%-33%) and 15% (95% CI 7%-26%) of patients by the N-Latex and Freelite™ assays, respectively. The combination of serum and urine immunofixation electrophoresis with either FLC assay allowed identification of the amyloidogenic clone in 98% producing comparable sensitivity. For the monitoring samples the median reduction in dFLC was 68% for the N-Latex assay and 77% for the Freelite™ assay (p=0.04). This led to some differences in assigning response categories. Partial response as assigned by both assays predicted overall survival (N-Latex p=0.0015, Freelite™ p=0.022).
There are differences between FLC as measured by the N-Latex and Freelite™ assays, but overall the two assays have similar diagnostic sensitivity. Disease response calculated by both assays predicts survival but more clinical validation is required.
我们比较了一种新型的游离轻链（FLC）定量检测方法（基于单克隆抗体的 N-Latex，德国西门子公司）与基于多克隆抗体的传统方法（FreeliteTM，英国 The Binding Site 公司）在 AL 淀粉样变性中的应用。
我们在 BNII 散射比浊仪上分析了 62 例诊断样本，其中 32 例样本有治疗后样本。
在诊断样本中：对于κ型 AL，N-Latex 检测法检测到的受累游离轻链（iFLC）中位数显著低于 FreeliteTM 检测法（289 比 667mg/L，p=0.0002），而对于 λ 型 AL，两种方法检测到的游离轻链值相似（148 比 161mg/L，p=0.84）。根据 N-Latex 检测法，有 82%的患者可检测到受累游离轻链和未受累游离轻链之间的差异（dFLC）>50mg/L，而根据 FreeliteTM 检测法，这一比例为 89%。对于诊断的灵敏度，N-Latex 检测法和 FreeliteTM 检测法分别有 21%（95%CI 12%-33%）和 15%（95%CI 7%-26%）的患者血清游离轻链比值正常。血清和尿液免疫固定电泳联合任何一种游离轻链检测方法均可识别出产生淀粉样变性的克隆，具有相似的灵敏度。对于监测样本，N-Latex 检测法和 FreeliteTM 检测法检测到的 dFLC 中位数降低分别为 68%和 77%（p=0.04）。这导致了两种检测方法在确定反应类别时存在差异。两种检测方法均将部分缓解作为预测总生存率的指标（N-Latex p=0.0015，FreeliteTM p=0.022）。
N-Latex 检测法和 FreeliteTM 检测法检测到的游离轻链存在差异，但总的来说，两种检测方法具有相似的诊断灵敏度。两种检测方法计算出的疾病反应均能预测生存率，但还需要更多的临床验证。
