Tzartos John S, Vakrakou Aigli G, Karagiorgou Katerina, Zouvelou Vasiliki, Chroni Elisabeth, Damato Valentina, Beretta Francesca, Salakou Stavroula, Sfyroera Eirini, Veltsista Dimitra, Voumvourakis Konstantinos, Giannopoulos Sotirios, Tsivgoulis Georgios, Tzartos Socrates
Second Department of Neurology ''Attikon'' University Hospital, School of Medicine, National and Kapodistrian University of Athens (NKUA), Athens, Greece.
First Department of Neurology, School of Medicine, Aeginition Hospital, National and Kapodistrian University of Athens, Athens, Greece.
Front Immunol. 2025 May 28;16:1459423. doi: 10.3389/fimmu.2025.1459423. eCollection 2025.
We investigated whether the acetylcholine receptor (AChR) cluster cell-based assay (CBA) is effective in detecting AChR antibodies in sera from myasthenia gravis (MG) patients with low antibody concentrations, as determined by radioimmunoprecipitation assay (RIPA).
In this retrospective diagnostic cohort study, 193 RIPA-positive sera from MG patients were analyzed. Following initial assessment using the gold-standard RIPA, samples were tested with a commercially available fixed CBA (F-CBA) and an in-house live CBA (L-CBA) to detect clustered AChR antibodies. Patients were classified into three groups based on RIPA levels to evaluate the sensitivity of each CBA. A subset of the cohort was blindly retested in a second laboratory to confirm results.
The sensitivity of L-CBA and F-CBA in detecting 36 sera with low AChR-antibody levels (1.0-2.8 nM) was relatively high for L-CBA (83.33%, 95% CI: 71.16%, 95.51%) and low for F-CBA (45.71%, 95% CI: 29.21% to 62.22%). Both CBAs were 100% sensitive for sera with AChR-RIPA values > 3 nM. Antibodies of RIPA+/CBA- sera could be immunoadsorbed on AChR-transfected cells equally well as those from RIPA+/CBA+ sera, indicating that CBA negativity was due to low antibody concentrations.
Overall, while AChR L-CBA demonstrates good sensitivity for detecting low concentrations of AChR antibodies, F-CBA performs less reliably in such cases. Since clustered AChR-CBAs can also identify antibodies that are not detectable by RIPA, we recommend that both RIPA and CBA be used together in the routine diagnosis of MG whenever possible. When available, L-CBA should be preferred over F-CBA due to its higher sensitivity.
我们研究了基于乙酰胆碱受体（AChR）簇细胞的检测方法（CBA）在检测重症肌无力（MG）患者血清中低抗体浓度的AChR抗体方面是否有效，该浓度由放射免疫沉淀法（RIPA）测定。
在这项回顾性诊断队列研究中，分析了193份MG患者的RIPA阳性血清。在使用金标准RIPA进行初步评估后，用市售的固定CBA（F-CBA）和内部活细胞CBA（L-CBA）检测样本，以检测聚集的AChR抗体。根据RIPA水平将患者分为三组，以评估每种CBA的敏感性。该队列的一个子集在第二个实验室进行盲法重新检测以确认结果。
L-CBA和F-CBA检测36份低AChR抗体水平（1.0 - 2.8 nM）血清的敏感性，L-CBA相对较高（83.33%，95%可信区间：71.16%，95.51%），F-CBA较低（45.71%，95%可信区间：29.21%至62.22%）。两种CBA对AChR-RIPA值>3 nM的血清敏感性均为100%。RIPA+/CBA-血清中的抗体与RIPA+/CBA+血清中的抗体一样能很好地免疫吸附在AChR转染细胞上，表明CBA阴性是由于抗体浓度低。
总体而言，虽然AChR L-CBA在检测低浓度AChR抗体方面显示出良好的敏感性，但F-CBA在这种情况下表现不太可靠。由于聚集的AChR-CBAs还可以识别RIPA无法检测到的抗体，我们建议在MG的常规诊断中尽可能同时使用RIPA和CBA。如果有L-CBA，因其敏感性较高，应优先于F-CBA使用。
