Palladini Giovanni, Jaccard Arnaud, Milani Paolo, Lavergne David, Foli Andrea, Bender Sebastien, Lavatelli Francesca, Bosoni Tiziana, Valentini Veronica, Pirolini Laura, Ferraro Giovanni, Basset Marco, Russo Francesca, Nuvolone Mario, Albertini Riccardo, Cogne Michel, Merlini Giampaolo
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Clin Chem Lab Med. 2017 Oct 26;55(11):1734-1743. doi: 10.1515/cclm-2016-1024.
The measurement of circulating free light chain (FLC) is essential in the diagnosis, prognostic stratification and evaluation of response to therapy in light chain (AL) amyloidosis. For more than 10 years, this has been done with an immunonephelometric assay based on polyclonal antibodies (Freelite), and cutoffs for staging and response assessment have been validated with this method. Recently, a new assay based on monoclonal antibodies (N latex FLC) has been marketed in Europe.
We evaluated and compared the clinical performance of the two assays in 426 patients with newly diagnosed AL amyloidosis.
We found suboptimal agreement between the two methods, with differences between values obtained with the Freelite and N latex FLC assays increasing with the concentration of clonal FLC. The diagnostic sensitivity of the Freelite (82%) and N latex FLC (84%) assays was similar, and both improved to 98% in combination with serum and urine immunofixation. The concentration of FLC measured with both methods had prognostic significance. Less pronounced decreases in FLC best predicted improved survival with the N latex FLC assay (33% vs. 50%), and there was poor concordance (84%) in discrimination of responders.
The two assays have similar diagnostic and prognostic performance. However, they are not interchangeable, and follow-up should be done with either one. New response criteria are needed for the N latex FLC assay.
循环游离轻链（FLC）的检测对于轻链型（AL）淀粉样变性的诊断、预后分层及治疗反应评估至关重要。十多年来，一直采用基于多克隆抗体的免疫比浊法（Freelite）进行此项检测，且分期及反应评估的临界值已通过该方法得到验证。最近，一种基于单克隆抗体的新检测方法（N乳胶FLC）已在欧洲上市。
我们评估并比较了这两种检测方法在426例新诊断的AL淀粉样变性患者中的临床性能。
我们发现这两种方法的一致性欠佳，Freelite和N乳胶FLC检测所获值之间的差异随克隆性FLC浓度的增加而增大。Freelite检测（82%）和N乳胶FLC检测（84%）的诊断敏感性相似，二者与血清及尿免疫固定电泳联合应用时诊断敏感性均提高至98%。两种方法测得的FLC浓度均具有预后意义。FLC下降不太明显时，N乳胶FLC检测对生存改善的预测效果更佳（33%对50%），且在区分反应者方面一致性较差（84%）。
这两种检测方法具有相似的诊断和预后性能。然而，它们不可互换，应使用其中一种进行随访。N乳胶FLC检测需要新的反应标准。
