Clinical Chemistry Service, Department of Laboratory Medicine, Memorial Sloan Kettering Cancer Center, New York, NY.
J Appl Lab Med. 2021 Nov 1;6(6):1551-1560. doi: 10.1093/jalm/jfab067.
Serum immunofixation (IF) is a common laboratory test used to diagnose and monitor patients with monoclonal gammopathies. Similarly, immunotyping (IT) by capillary electrophoresis can confirm the presence of a monoclonal protein (M-protein) and determine its isotype. The goal of this study was to compare the ability of IT and IF to detect M-proteins.
IT and IF results for 1000 waste clinical serum samples were obtained. All results were interpreted blindly by reviewers who were experienced in each technique. Results were compared by band. Results were also compared to patient history to determine if the original clone was present. We determined the sensitivity of IT and IF alone and in combination with additional tests. Finally, we evaluated the impact of reviewer training on the sensitivity of IT.
IT and IF were concordant in 721/773 (93%) samples with a history of an intact M-protein and in 143/172 (83%) samples with a history of a free light chain (FLC) M-protein. IF was significantly more sensitive than IT for the detection of FLC M-proteins (P < 0.0001). However, IF was not more sensitive than IT for detection of intact M-proteins (P = 0.1272) or when each test was combined with the FLC ratio or urine immunofixation (P = 0.2812 and P = 0.6171, respectively). Finally, after training, inexperienced reviewers improved their IT sensitivity by 19%.
IT provides equivalent results to IF for the detection of monoclonal proteins. Training and experience are critical to the accurate interpretation of IT.
血清免疫固定电泳（IF）是一种常用于诊断和监测单克隆丙种球蛋白病患者的常用实验室检测。同样，毛细管电泳免疫分型（IT）可确认单克隆蛋白（M 蛋白）的存在并确定其型别。本研究旨在比较 IT 和 IF 检测 M 蛋白的能力。
获得了 1000 例临床废血清样本的 IT 和 IF 结果。由经验丰富的每位技术的审阅者对所有结果进行盲法解读。通过带进行比较。还将结果与患者病史进行比较，以确定是否存在原始克隆。我们确定了 IT 和 IF 单独以及与其他测试联合使用的灵敏度。最后，我们评估了审阅者培训对 IT 灵敏度的影响。
在有完整 M 蛋白病史的 721/773 例（93%）样本和有游离轻链（FLC）M 蛋白病史的 143/172 例（83%）样本中，IT 和 IF 结果一致。对于 FLC M 蛋白的检测，IF 明显比 IT 更敏感（P < 0.0001）。然而，对于完整 M 蛋白的检测，IF 并不比 IT 更敏感（P = 0.1272），或者当每种测试与 FLC 比值或尿液免疫固定电泳结合使用时（P = 0.2812 和 P = 0.6171）。最后，经过培训，无经验的审阅者将他们的 IT 灵敏度提高了 19%。
IT 对检测单克隆蛋白提供与 IF 相当的结果。培训和经验对 IT 的准确解读至关重要。
