Department of Neurology, Erasmus MC University Medical Center, 3015 GD Rotterdam, The Netherlands.
Department of Clinical Chemistry, Erasmus MC University Medical Center, 3015 GD Rotterdam, The Netherlands.
J Proteome Res. 2020 Jul 2;19(7):2845-2853. doi: 10.1021/acs.jproteome.9b00705. Epub 2020 Jan 14.
Serum protein electrophoresis (SPE) and immunofixation electrophoresis (IFE) are standard tools for multiple myeloma (MM) routine diagnostics. M-protein is a biomarker for MM that can be quantified with SPE and characterized with IFE. We have investigated combining SPE/IFE with targeted mass spectrometry (MS) to detect and quantify the M-protein. SPE-MS assay offers the possibility to detect M-protein with higher sensitivity than SPE/IFE, which could lead to better analysis of minimal residual disease in clinical laboratories. In addition, analysis of archived SPE gels could be used for retrospective MM studies. We have investigated two different approaches of measuring M-protein and therapeutic monoclonal antibodies (t-mAbs) from SPE/IFE gels. After extracting proteotypic peptides from the gel, they can be quantified using stable isotope labeled (SIL) peptides and measured by Orbitrap mass spectrometry. Alternatively, extracted peptides can be labeled with tandem mass tags (TMT). Both approaches are not hampered by the presence of t-mAbs. Using SIL peptides, limit of detection of the M-protein is approximately 100-fold better than with routine SPE/IFE. Using TMT labeling, M-protein can be compared in different samples from the same patient. We have successfully measured M-protein proteotypic peptides extracted from the SPE/IFE gels utilizing SIL peptides and TMT.
血清蛋白电泳（SPE）和免疫固定电泳（IFE）是多发性骨髓瘤（MM）常规诊断的标准工具。M 蛋白是 MM 的生物标志物，可通过 SPE 进行定量，并通过 IFE 进行特征分析。我们研究了将 SPE/IFE 与靶向质谱（MS）相结合，以检测和定量 M 蛋白。SPE-MS 检测方法比 SPE/IFE 具有更高的检测 M 蛋白的灵敏度，这可能会导致临床实验室中对微小残留病的分析更好。此外，还可以对存档的 SPE 凝胶进行分析，以用于回顾性 MM 研究。我们研究了从 SPE/IFE 凝胶中测量 M 蛋白和治疗性单克隆抗体（t-mAb）的两种不同方法。从凝胶中提取特征肽后，可使用稳定同位素标记（SIL）肽进行定量，并通过 Orbitrap 质谱法进行测量。或者，可以用串联质量标签（TMT）标记提取的肽。这两种方法都不受 t-mAb 的存在的影响。使用 SIL 肽，M 蛋白的检测限比常规 SPE/IFE 好约 100 倍。使用 TMT 标记，可以比较同一患者不同样本中的 M 蛋白。我们已经成功地使用 SIL 肽和 TMT 测量了从 SPE/IFE 凝胶中提取的 M 蛋白特征肽。
