摘要目的:基于二氧四氢喋啶合酶（LS）多聚纳米抗体，建立一种检测血清中可溶性细胞程序性死亡-配体1（PD-L1）蛋白的方法。方法:采用竞争ELISA筛选识别PD-L1不同表位的纳米抗体作为配对抗体，建立双纳米抗体夹心ELISA检测方法（Nbs-ELISA）。为了进一步提高敏感性，将纳米抗体与LS进行融合，获得多聚形式的纳米抗体作为sPD-L1蛋白的捕获分子，建立基于LS的多聚纳米抗体ELISA检测方法（LSNbs-ELISA）。结果:与Nbs-ELISA方法相比，LSNbs-ELISA方法对sPD-L1的检测敏感性提高了约11倍，Nbs-ELISA对血清中sPD-L1的检出限为2.87 ng/ml，而LSNbs-ELISA对PD-L1的检出限为0.255 ng/ml。2种检测方法对sPD-L1的检测均具有很高的特异性，与掺入血液中的PD-1、CD27、CD70、CD137和CD147蛋白均不结合。结论:建立的基于LS多聚纳米抗体检测血清中PD-L1的检测方法有较高的敏感性和特异性，对肺癌患者血清中可溶性PD-L1的检测具有潜在的临床应用价值。

abstractsObjective:To established a method for the detection of soluble programmed death ligand 1 (PD-L1) protein in serum based on the poly nanoantibody of lumazine synthase(LS).Methods:A dual nanobody-based sandwich ELISA was established with a competitive ELISA to screen nanobodies recognizing different epitopes of PD-L1 as paired antibodies. To improve sensitivity, PD-L1 nanobody P3C8 and lumazine synthase(LS) were fused, and nanobodies were obtained in polymeric forms as sPD-L1 protein captures, so as to develop an LS-displayed polymeric nanobody-based sandwich ELISA (LSNbs-ELISA) method to detect sPD-L1.Results:Compared with the Nbs-ELISA method, the LSNbs-ELISA method is approximately 11-fold more sensitive for sPD-L1 detection. The limit of detections (LODs) of Nbs-ELISA and LSNbs-ELISA for sPD-L1 in serum were 2.87 ng/ml and 0.255 ng/ml, respectively. Both assays were highly specific for the detection of sPD-L1 and did not react with structure-related proteins PD-1, CD27, CD70, CD137, and CD147 when spiked into the human serum.Conclusions:The Nbs-ELISA and LSNbs-ELISA assays both have high sensitivity and specificity for detecting sPD-L1 in serum and could have potential clinical applications.