Background The EXENT® system is an automated platform designed to quantify monoclonal immunoglobulins in serum. EXENT® combines immunoprecipitation and MALDI-TOF mass spectrometry for the detection of monoclonal immunoglobulins at levels lower than traditional gel based methods. This study was designed to demonstrate if EXENT® prepared samples that were negative could be reflexed to a more sensitive method based on capillary flow Liquid Chromatography- Mass Spectrometry (LC-MS) without any modifications to the EXENT® prepared sample. Methods Patient samples containing a monoclonal immunoglobulin (ranging from 20 to 40 g/L) were diluted into pooled polyclonal serum and the samples were prepared and analyzed by EXENT®. Samples that were negative by EXENT® were reflexed by directly loading EXENT® eluates onto the LC-MS instrument. The abundance of the monoclonal immunoglobulin was defined by the signal-to-noise (S/N) of the light chain peak observed after deconvolution. Results Baseline samples were diluted down to two levels, 0.100 g/L and 0.001 g/L. LC-MS detected the same light chain from the monoclonal immunoglobulin as the EXENT® system in all reflexed samples that were negative by EXENT®. Conclusions LC-MS can detect monoclonal immunoglobulins that can no longer be detected using the EXENT® system by tracking the unique molecular mass of the monoclonal light chain. Reflexing samples to LC-MS did not require additional sample handling resulting in a faster time-to-result than current NGS, NGF, and clonotypic peptide approaches. Furthermore, monitoring the intact monoclonal light chain circumvents enzymatic cleavage to create a unique clonotypic peptide, alleviating a situation where no unique peptide can be generated as has been shown previously by Bergen et al. As a consequence, this reflex-methodology results in a consistent way of measuring the presence of malignant B-cells with high sensitivity.

中文翻译：

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B-169 结合 EXENT 系统和 LC-MS 检测低水平的单克隆免疫球蛋白


背景 EXENT® 系统是一个自动化平台，旨在量化血清中的单克隆免疫球蛋白。 EXENT® 结合了免疫沉淀和 MALDI-TOF 质谱法，用于检测水平低于传统凝胶方法的单克隆免疫球蛋白。本研究旨在证明 EXENT® 制备的阴性样品是否可以反映到基于毛细管流动液相色谱-质谱 (LC-MS) 的更灵敏的方法，而无需对 EXENT® 制备的样品进行任何修改。方法 将含有单克隆免疫球蛋白（范围为 20 至 40 g/L）的患者样本稀释到混合多克隆血清中，并通过 EXENT® 制备和分析样本。通过将 EXENT® 洗脱液直接加载到 LC-MS 仪器上，对 EXENT® 呈阴性的样品进行反射。单克隆免疫球蛋白的丰度由去卷积后观察到的轻链峰的信噪比 (S/N) 定义。结果 基线样品被稀释至两个水平：0.100 g/L 和 0.001 g/L。 LC-MS 在 EXENT® 阴性的所有反射样品中检测到与 EXENT® 系统相同的单克隆免疫球蛋白轻链。结论 LC-MS 可以通过追踪单克隆轻链的独特分子质量来检测使用 EXENT® 系统无法再检测到的单克隆免疫球蛋白。将样品反射至 LC-MS 不需要额外的样品处理，从而比当前的 NGS、NGF 和克隆型肽方法更快地获得结果。此外，监测完整的单克隆轻链可以避免酶促裂解，从而产生独特的克隆型肽，从而缓解无法生成独特肽的情况，正如 Bergen 等人之前所证明的那样。 因此，这种反射方法能够以一致的方式以高灵敏度测量恶性 B 细胞的存在。