ARUP Laboratories, Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, United States of America.
NMS Laboratories, Willow Grove, PA, United States of America.
J Immunol Methods. 2019 Jul;470:33-39. doi: 10.1016/j.jim.2019.04.008. Epub 2019 Apr 26.
TNF antagonists such as infliximab are effective for the treatment of several inflammatory and autoimmune diseases. Recent clinical studies have advocated the importance of measuring trough infliximab levels to guide treatment decisions. We have developed a novel assay for measuring serum free infliximab levels using inductively coupled plasma-mass spectrometry (ICP-MS). The method involves the incubation of patient serum in wells coated with recombinant TNF, followed by detection with lanthanide-labeled monoclonal anti-human IgG1 and ICP-MS analysis. Full method validation was performed and results for clinical samples tested with the new method were compared with those obtained from a capture ELISA and a cell-based assay. Validation of the ICP-MS assay revealed a lower limit of detection of 0.4 μg/mL in serum. The linear range of quantitation was 1-50 μg/mL. The within-run and between-run precision had a coefficient of variation (CV) of <10%, and the accuracy of the assay had a CV of <15%. In serum samples, the ICP-MS method was devoid of analytical interferences by high levels of hemoglobin, bilirubin and triglycerides. Serum sample results from 123 drug-naïve donors revealed a test cutoff at 0.5 μg/mL. Test results from clinical samples obtained by the ICP-MS method showed strong correlation with both the ELISA and cell-based assay. The ICP-MS methodology presented in this study is a robust method for measuring TNF antagonist serum levels, which makes it well suited for therapeutic drug monitoring in the clinical laboratory.
TNF 拮抗剂，如英夫利昔单抗，对多种炎症性和自身免疫性疾病的治疗有效。最近的临床研究强调了测量 TNF 拮抗剂（如英夫利昔单抗）谷浓度来指导治疗决策的重要性。我们开发了一种使用电感耦合等离子体质谱法（ICP-MS）测量血清游离英夫利昔单抗浓度的新方法。该方法涉及将患者血清与包被重组 TNF 的孔孵育，然后用镧系标记的单克隆抗人 IgG1 检测，并用 ICP-MS 分析。对该方法进行了全面验证，并将新方法检测的临床样本结果与捕获 ELISA 和基于细胞的测定法进行了比较。ICP-MS 测定法的验证结果显示，血清中的检测下限为 0.4μg/mL。定量线性范围为 1-50μg/mL。批内和批间精密度的变异系数（CV）<10%，测定法的准确性 CV<15%。在血清样本中，该 ICP-MS 方法不受血红蛋白、胆红素和甘油三酯等高水平的分析干扰。123 名未经药物治疗的供体血清样本的结果显示，检测截断值为 0.5μg/mL。通过 ICP-MS 方法获得的临床样本的检测结果与 ELISA 和基于细胞的测定法均具有很强的相关性。本研究中提出的 ICP-MS 方法是一种测量 TNF 拮抗剂血清水平的可靠方法，非常适合临床实验室的治疗药物监测。
