Analytical Biochemistry, Department of Pharmacy, University of Groningen , Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
Anal Chem. 2017 Jun 6;89(11):6188-6195. doi: 10.1021/acs.analchem.7b01125. Epub 2017 May 10.
Analytical methods based on mass spectrometry (MS) have been successfully applied in biomarker discovery studies, while the role of MS in translating biomarker candidates to clinical diagnostics is less pronounced. MALDImmunoassays-methods that combine immunoaffinity enrichment with matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometric detection-are attractive analytical approaches for large-scale sample analysis by virtue of their ease of operation and high-throughput capabilities. Despite this fact, MALDImmunoassays are not widely used in clinical diagnostics, which is mainly due to the limited availability of internal standards that can adequately correct for variability in sample preparation and the MALDI process itself. Here we present a novel MALDImmunoassay for quantification of insulin-like growth factor 1 (IGF1) in human plasma. Reliable IGF1 quantification in the range of 10-1000 ng/mL was achieved by employing N-IGF1 as internal standard, which proved to be an essential feature of the IGF1 MALDImmunoassay. The method was validated according to U.S. Food and Drug Administration (FDA) guidelines, which included demonstrating the effectiveness of IGF1/IGF binding protein (IGF1/IGFBP) complex dissociation using sodium dodecyl sulfate (SDS). Furthermore, the MALDImmunoassay compared well with the IDS-iSYS IGF1 immunoassay with high correlation (R = 0.99), although substantially lower levels were reported by the MALDImmunoassay. The method was tested on >1000 samples from a cohort of renal transplant recipients to assess its performance in a clinical setting. On the basis of this study, we identified readouts to monitor the quality of the measurements. Our work shows that MALDI-TOF mass spectrometry is suitable for quantitative biomarker analysis provided that an appropriate internal standard is used and that readouts are monitored to assess the quality of the measurements.
基于质谱 (MS) 的分析方法已成功应用于生物标志物发现研究，而 MS 在将生物标志物候选物转化为临床诊断中的作用则不那么明显。MALDI 免疫测定-将免疫亲和富集与基质辅助激光解吸电离飞行时间 (MALDI-TOF) 质谱检测相结合的方法-由于其操作简单和高通量的特点，是用于大规模样品分析的有吸引力的分析方法。尽管如此，MALDI 免疫测定并未广泛用于临床诊断，这主要是由于缺乏内部标准，这些标准无法充分纠正样品制备和 MALDI 过程本身的变异性。在这里，我们提出了一种新的 MALDI 免疫测定法，用于定量测定人血浆中的胰岛素样生长因子 1 (IGF1)。通过使用 N-IGF1 作为内标，可靠地实现了 10-1000ng/mL 范围内的 IGF1 定量，这被证明是 IGF1 MALDI 免疫测定的一个重要特征。该方法根据美国食品和药物管理局 (FDA) 的指南进行了验证，其中包括证明使用十二烷基硫酸钠 (SDS) 有效解离 IGF1/IGF 结合蛋白 (IGF1/IGFBP) 复合物。此外，该 MALDI 免疫测定法与 IDS-iSYS IGF1 免疫测定法高度相关 (R=0.99)，尽管 MALDI 免疫测定法报告的水平要低得多。该方法在来自肾移植受者队列的 >1000 个样本上进行了测试，以评估其在临床环境中的性能。基于这项研究，我们确定了用于监测测量质量的读数。我们的工作表明，MALDI-TOF 质谱法适用于定量生物标志物分析，前提是使用适当的内标，并监测读数以评估测量质量。
