Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
Clin Biochem. 2022 Sep;107:7-12. doi: 10.1016/j.clinbiochem.2022.05.011. Epub 2022 Jun 1.
Quantification of monoclonal protein (M-protein) by serum protein electrophoresis (SPE) is indispensable for diagnosing and monitoring monoclonal gammopathies. However, quantification of small and beta migrating M-proteins is challenging because of overlapping non-immunoglobulin and/or polyclonal immunoglobulin protein fractions. We compared a new integration method based on immunosubtraction (IS-CE) using capillary zone electrophoresis (CZE) against the routine method, which includes a combination of perpendicular drop (0.4%), corrected perpendicular drop (1%) and tangent skimming (98.5%).
DESIGN & METHODS: The proposed method of M-protein quantification involves calculating the difference in area under the curve between the SPE and a class-specific IS-CE trace. We analyzed the difference in estimated M-protein concentrations obtained with the new method and routine integration methods using 913 samples. For IgA M-proteins at < 10 g/L, the estimated M-protein concentrations were compared with the total IgA concentration.
The median M-protein concentration of 913 consecutive samples was 6.2 g/L (IQR 2.1-14.3 g/L). The median and median % difference between the two integration methods was 0.68 g/L (IQR 0.01-1.55 g/L) and 10.9% (IQR 0.18-38.7%), showing a larger estimated M-protein concentration with the new method. More than 25% difference was observed in 38% of the samples and was associated with lower total protein concentration, lower M-protein concentration, IgA and IgM heavy chain isotypes, and beta- or beta-gamma migration. When 161 samples with IgA M-protein < 10 g/L were compared against total IgA concentration, the median bias of the new method was smaller compared to that of the existing method (-0.95 g/L vs. -1.3 g/L, P < 0.0001).
The use of IS based integration using CZE and IS-CE is promising especially for small and beta migrating M-proteins.
通过血清蛋白电泳（SPE）定量单克隆蛋白（M 蛋白）对于诊断和监测单克隆丙种球蛋白病是不可或缺的。然而，由于重叠的非免疫球蛋白和/或多克隆免疫球蛋白蛋白部分，定量小的和β迁移的 M 蛋白具有挑战性。我们比较了一种新的基于免疫吸附（IS）的整合方法，该方法使用毛细管区带电泳（CZE），与包括垂直滴（0.4%）、校正垂直滴（1%）和切线刮削（98.5%）相结合的常规方法进行对比。
M 蛋白定量的新方法涉及计算 SPE 下的曲线下面积与特定类别免疫吸附 CZE 痕迹之间的差异。我们使用 913 个样本分析了新方法和常规积分方法获得的估计 M 蛋白浓度的差异。对于 <10g/L 的 IgA M 蛋白，将估计的 M 蛋白浓度与总 IgA 浓度进行比较。
913 例连续样本的中位数 M 蛋白浓度为 6.2g/L（IQR 2.1-14.3g/L）。两种积分方法的中位数和中位数差异分别为 0.68g/L（IQR 0.01-1.55g/L）和 10.9%（IQR 0.18-38.7%），表明新方法的估计 M 蛋白浓度更大。在 38%的样本中观察到超过 25%的差异，与总蛋白浓度较低、M 蛋白浓度较低、IgA 和 IgM 重链同种型以及β或β-γ迁移有关。当将 161 例 IgA M 蛋白<10g/L 的样本与总 IgA 浓度进行比较时，新方法的中位偏差小于现有方法（-0.95g/L 与-1.3g/L，P<0.0001）。
使用 CZE 和 IS-CE 的基于 IS 的整合是有前途的，特别是对于小的和β迁移的 M 蛋白。
