重症肌无力相关抗体的临床意义

Clinical significance of myasthenia gravis-related autoantibodies

目的探讨重症肌无力(MG)相关抗体与 MG 的临床关系。方法采用酶联免疫吸附法(ELISA)检测74例 MG 患者血清乙酰胆碱受体抗体(AChR-ab)、肌联蛋白抗体(Titin-ab)和利阿诺碱受体抗体(RyR-ab)水平。结果 AChR-ab、Titin-ab 和 RyR-ab 在所有 MG 患者中阳性率分别为77.0%(57/74)、39.2%(29/74)和32.4%(24/74),3种抗体总阳性率为93.2%(69/74)。在 MG 合并胸腺瘤的21例患者中阳性率分别为76.2%(16/21)、71.4%(15/21)和52.4%(11/21),3种抗体总阳性率为95.6%(20/21)。与早发患者相比,晚发患者中 Titin-ab 和 RyR-ab 水平明显升高[早发患者:23.1%(12/52)和25.0%(13/52),晚发患者:77.3%(17/22)和50.0%(11/22),P<0.01]。按改良 Osserman 分型症状较重者 Titin-ab(X^2=16.094,P=0.001)和 RyR-ab(X^2=11.226,P=0.011)阳性率亦高,Titin-ab 和 RyR-ab 有明显相关性(r=0.380,P=0.001)。结论 Titin-ab 和 RyR-ab 检测有助于 MG 合并胸腺瘤的诊断,与影像学检查结合可以提高 MG 合并胸腺瘤诊断的特异性和敏感性;Titin-ab 和 RyR-ab 的水平还可作为随诊和评估 MG 患者预后的指标。这两种抗体的产生过程及其作用机制有待进一步研究。

Objective To investigate the clinical significance of myasthenia gravis （MG） associated autoantibodies. Methods Titin, ryanodine receptor （RyR）and acetylcholine receptor （AChR） antibodies were examined in the sera of 74 myasthenia gravies patients by ELISA. Results AChR, Titin, RyR antibodies were detected in 77.0% （ 57/74 ）, 39. 2% （ 29/74 ） and 32. 4% （ 24/74 ） of the MG patients, respectively. For thymoma MG, AChR, Titin and RyR antibodies were detected in 76. 2% （ 16/21 ）, 71.4% （ 15/21 ） and 52. 4% （ 11/21 ） respectively. For late onset MG, Titin and RyR antibodies were detected in 77.3% （17/22） and 50. 0% （11/22） respectively. With respect to the modified Osserman classification, the positve rate for Titin and RyR antibodies is much higher in more severe patients （x^2 = 16. 094, P = 0. 001 ; x^2 = 11. 226, P = 0. 011 ） . Titin antibodies was significantly related with RyR antibodies （r = 0. 380, P = 0. 001 ）. Conclusions Titin and RyR antibodies show high sensitivity for thymoma MG, and the combination of serological and radiological testing can increase both sensitivity and specificity in diagnosis of thymoma MG. The levels of the two antibodies may serve as important prognosis markers in MG. The induction of the immune response against Titin and RyR and the possible pathogenic effects of the two antibodies will be further studied.