| 摘要: | 儘管質譜(MS)技術已經有所進步，但其轉化為臨床實驗室仍面臨著維持穩定性和一 致性的重大挑戰，尤其是當技術人員和儀器設備出現變更時。我們先前以甲狀腺球蛋白 (Tg)作為甲狀腺癌的生物標記，並採用免疫多重反應監測質譜(iMRM MS)檢測作為 模型，建立符合臨床實驗室改進修正案(CLIA)的實驗室。建立在前期工作的基礎上， 本研究旨在評估此臨床實驗室的操作過程，以確保在不同條件下的高度重複性和再現性。
作為新進的實驗人員，我接受了 Tg-iMRM MS 檢測的操作培訓，該檢測最初由華盛頓 大學的 Andrew Hoofnagle 醫師開發，使用基於胜肽的免疫沉澱與 MRM MS 定量檢測甲狀 腺癌患者的 Tg 濃度。初步測試發現不同實驗人員和質譜儀的之間有低再現性。我發現合 成內部標準品(SIS)的分批均一性對檢測表現有顯著影響。通過評估通過品質管理(QC) 的批次數據，發現在每次實驗先監控 SIS 胜肽強度是否落於約 148,500 至 222,800 的區間， 不同批次間 SIS 表現可保持一致性，三個品質管理(QC)樣本顯示了良好的定量結果: 精準度分別為 QC-Low(0.92 ng/mL，CV 10.29%)、QC-Mid(3.12 ng/mL，CV 10.63%) 和 QC-High(9.78 ng/mL，CV 5.35%)，從而減少變異性並增加檢測的可靠性。此外，將 2% DMSO 加入移動相使信號強度增加了 2.43 倍，顯著提升檢測的靈敏度和一致性。
將 Tg-iMRM MS 檢測應用於擁有不同甲狀腺球蛋白自身抗體(TgAb)水平的患者血清 樣本中:包括 69 名低 TgAb 水平(<3 IU/mL)的患者和 8 名中等 TgAb 水平(3 至 16 IU/mL)的患者，這些水平是通過傳統 ECLIA 方法測量而得。對於不含 TgAb 的樣本， ECLIA 和 iMRM-MS 在 Tg 定量結果上達到良好的一致性。而 iMRM-MS 在含有 TgAb 的 樣本中則有著更佳的表現，尤其是能夠在含有顯著 TgAb 水平的樣本中定量低濃度的 Tg。 我們仍需要進一步的實驗來全面評估檢測在不同操作者和儀器設置中的表現。這項持續的 工作將有助於確立 Tg-iMRM MS 檢測在更廣泛應用的潛力，特別是減少存在 TgAb 樣本中 常見的假陰性結果。;Despite advancements in mass spectrometry technology, its translation into clinical laboratories face significant challenges in maintaining robustness and consistency, especially variations in operators and instrumentation. We previously utilized thyroglobulin (Tg) as a biomarker for thyroid cancer and employed an immuno-MRM (iMRM) MS-based assay as a model to establish a Clinical Laboratory Improvement Amendments (CLIA) compliant laboratory. Building on the previous work, this study aims to evaluate the repeatability and reproducibility under varying conditions within this clinical laboratory.
As a new operator, I have gone through the operation training on the Tg-iMRM MS assay, initially developed by Dr. Andrew Hoofnagle’s group at University of Washington that employs peptide-based immunoprecipitation coupled with MRM MS for quantitation of Tg. The initial testing encountered poor reproducibility by different operators and mass spectrometers. I found that the homogeneous aliquots of the synthetic internal standard (SIS) significantly affect the assay performance. Through examining the SIS peptide intensities for the data batch that passed the quality control (QC), systematic monitoring of SIS intensity within the range of around 148,600 to 222,800 at the beginning of each experiment can ensure the signal stability of SIS. With consistent SIS performance across different batches, the three quality control (QC) samples show satisfactory quantification results with accuracy of QC-Low (0.92 ng/mL, CV 10.29%), QC-Mid (3.12 ng/mL, CV 10.63%), and QC-High (9.78 ng/mL, CV 5.35%), thereby minimizing variability to maintain assay reliability. Additionally, incorporating 2% DMSO in the mobile phase resulted in a 2.43-fold increase in signal intensity that improves both the sensitivity and consistency of the assay.
The Tg-iMRM MS assay was applied to the serum samples from patients with different thyroglobulin autoantibody (TgAb) levels measured by traditional ECLIA method: 69 patients with low levels (<3 IU/mL) and 8 patients with mid-levels (3 to 16 IU/mL). Good agreement in ECLIA and iMRM-MS was observed for samples without TgAb. The iMRM-MS shows superior performance in samples in the presence of TgAb, especially in samples with significant levels of TgAb. Further experiments are required to fully assess the assay′s performance across different operators and instrumental setups. This ongoing work will help establish the assay′s potential for broader clinical application, particularly in reducing false-negative results in TgAb prevalent samples. |
