基于细胞的IgG特异性检测法可检测血清阴性重症肌无力患者中潜在致病性抗肌肉特异性激酶抗体。
IgG-specific cell-based assay detects potentially pathogenic MuSK-Abs in seronegative MG.
作者信息
Huda Saif, Waters Patrick, Woodhall Mark, Leite Maria Isabel, Jacobson Leslie, De Rosa Anna, Maestri Michelangelo, Ricciardi Roberta, Heckmann Jeannine M, Maniaol Angelina, Evoli Amelia, Cossins Judy, Hilton-Jones David, Vincent Angela
机构信息
Nuffield Department of Clinical Neurosciences (S.H., P.W., M.W., M.I.L., L.J., J.C., D.H.-J., A.V.), University of Oxford, UK; Department of Clinical and Experimental Medicine (A.D.R., M.M., R.R.), Neurology Unit, Pisa, Italy; Division of Neurology (J.M.H.), University of Cape Town, South Africa; Oslo University Hospital (A.M.), Norway; and Department of Neuroscience (A.E.), Catholic University, Rome, Italy.
出版信息
Neurol Neuroimmunol Neuroinflamm. 2017 Jun 5;4(4):e357. doi: 10.1212/NXI.0000000000000357. eCollection 2017 Jul.
OBJECTIVE
To increase the detection of MuSK-Abs using a CBA and test their pathogenicity.
METHODS
Sera from 69 MuSK-RIA-positive patients with myasthenia gravis (MG) (Definite MuSK-MG), 169 patients negative for MuSK-RIA and AChR-RIA (seronegative MG, SNMG), 35 healthy individuals (healthy controls, HCs), and 16 NMDA receptor-Ab-positive (NMDAR-Ab) disease controls were tested for binding to MuSK on a CBA using different secondary antibodies.
RESULTS
Initially, in addition to 18% of SNMG sera, 11% of HC and 19% of NMDAR-Ab sera showed positive binding to MuSK-transfected cells; this low specificity was due to anti-IgG(H+L) detection of IgM bound nonspecifically to MuSK. Using an IgG Fc gamma-specific secondary antibody, MuSK-Abs were detected by CBA in 68/69 (99%) of Definite MuSK-MG, 0/35 HCs, 0/16 NMDAR-Ab, and 14/169 (8%) of SNMG sera, providing increased sensitivity with high specificity. The RIA-negative, CBA-positive MuSK-IgG sera, but not IgM-MuSK-binding sera, reduced agrin-induced AChR clustering in C2C12 myotubes, qualitatively similar to RIA-positive MuSK-Abs.
CONCLUSIONS
An IgG-specific MuSK-CBA can reliably detect IgG MuSK-Abs and increase sensitivity. In the MuSK-CBA, IgG specificity is essential. The positive sera demonstrated pathogenic potential in the in vitro AChR-clustering assay, although less effective than Definite MuSK-MG sera, and the patients had less severe clinical disease. Use of IgG-specific secondary antibodies may improve the results of other antibody tests.
CLASSIFICATION OF EVIDENCE
This study provides Class III evidence that an IgG-specific MuSK-CBA identifies patients with MG.
目的
采用CBA法提高MuSK抗体（MuSK-Abs）的检测率并检测其致病性。
方法
使用不同的二抗，通过CBA法检测69例MuSK放射免疫分析（RIA）阳性的重症肌无力（MG）患者（确诊的MuSK-MG）、169例MuSK-RIA和乙酰胆碱受体RIA（AChR-RIA）均阴性的患者（血清阴性MG，SNMG）、35名健康个体（健康对照，HCs）以及16例N-甲基-D-天冬氨酸受体抗体（NMDAR-Ab）阳性的疾病对照血清与MuSK的结合情况。
结果
最初，除18%的SNMG血清外，11%的HC血清和19%的NMDAR-Ab血清显示与MuSK转染细胞有阳性结合；这种低特异性是由于抗IgG（H+L）检测到非特异性结合MuSK的IgM。使用IgG Fcγ特异性二抗，通过CBA法在68/69（99%）的确诊MuSK-MG、0/35 HCs、0/16 NMDAR-Ab以及14/169（8%）的SNMG血清中检测到MuSK-Abs，提高了敏感性且特异性高。RIA阴性、CBA阳性的MuSK-IgG血清，而非IgM-MuSK结合血清，可减少聚集蛋白诱导的C2C12肌管中AChR聚集，在质量上与RIA阳性的MuSK-Abs相似。
结论
IgG特异性MuSK-CBA能可靠地检测IgG MuSK-Abs并提高敏感性。在MuSK-CBA中，IgG特异性至关重要。阳性血清在体外AChR聚集试验中显示出致病潜力，尽管不如确诊的MuSK-MG血清有效，且患者临床疾病较轻。使用IgG特异性二抗可能会改善其他抗体检测的结果。
证据分类
本研究提供了III类证据，即IgG特异性MuSK-CBA可识别MG患者。
Zotero 插件