Department of Rheumatology and Immunology, Peking University People's Hospital, Beijing 100044, China.
Chin Med J (Engl). 2011 Aug;124(16):2490-5.
Antibodies against type 3 muscarinic acetylcholine receptor (M3R) are involved in the pathogenesis of Sjögren's syndrome (SS), but the clinical value of them in SS patients has been controversial. The aims of this study were to: (1) establish an improved enzyme-linked immunosorbent assay (ELISA) to detect IgA antibodies against M3R; (2) evaluate the value of IgA antibodies against the second extracellular loop of M3R205-220 (c2M3RP) in diagnosis of SS.
To increase the ELISA sensitivity, c2M3RP was coupled to bovine serum albumin (BSA) by the glutaraldehyde method and a 96-well microplate was treated by ultraviolet rays before coated. Concentrations of anti-c2M3RP, anti-SSA, and anti-SSB were measured in the sera of 240 individuals: 91 patients with primary SS and 149 controls (16 secondary SS, 27 systemic lupus erythematosus, 40 rheumatoid arthritis and 66 healthy controls). Diagnostic properties of anti-c2M3RP were determined by receiver-operating characteristic curve analysis.
The prevalence of serum IgA anti-c2M3RP antibodies in patients with pSS (46%, 42/91) was significantly higher than that in patients with systemic lupus erythematosus (19%, 5/27), in rheumatoid arthritis (15%, 6/40) and in healthy controls (5%, 3/66). However, there was no significant difference between the two SS groups (P = 0.727). The diagnostic performance of IgA anti-M3RP antibodies was similar to anti-SSA assay, but had 22% higher sensitivity than anti-SSB. By analyzing of IgA anti-c2M3RP antibodies, combination of anti-SSA and anti-SSB resulted in increased sensitivity, whereas their specificity was not significantly changed.
The improved anti-c2M3RP ELISA is a novel, sensitive, and specific serological test for the diagnosis of SS. The combined application of anti-c2M3RP, anti-SSA and anti-SSB tests can improve the laboratory diagnosis of SS. The IgA anti-c2M3RP antibodies may serve as a novel diagnostic marker for SS.
针对 3 型毒蕈碱乙酰胆碱受体（M3R）的抗体与干燥综合征（SS）的发病机制有关，但它们在 SS 患者中的临床价值一直存在争议。本研究旨在：（1）建立一种改良的酶联免疫吸附试验（ELISA）检测针对 M3R 的 IgA 抗体；（2）评估针对 M3R 第二细胞外环 205-220 位（c2M3RP）的 IgA 抗体在 SS 诊断中的价值。
为提高 ELISA 的灵敏度，采用戊二醛法将 c2M3RP 与牛血清白蛋白（BSA）偶联，并用紫外线处理 96 孔微孔板。在 240 名个体的血清中测量了抗 c2M3RP、抗 SSA 和抗 SSB 的浓度：91 名原发性 SS 患者和 149 名对照者（16 名继发性 SS、27 名系统性红斑狼疮、40 名类风湿关节炎和 66 名健康对照者）。通过接收者操作特征曲线分析确定抗 c2M3RP 的诊断特性。
pSS 患者血清 IgA 抗 c2M3RP 抗体的阳性率（46%，42/91）明显高于系统性红斑狼疮患者（19%，5/27）、类风湿关节炎患者（15%，6/40）和健康对照组（5%，3/66）。然而，两组 SS 患者之间无显著差异（P = 0.727）。IgA 抗 M3RP 抗体的诊断性能与抗 SSA 检测相似，但敏感性高 22%。通过分析 IgA 抗 c2M3RP 抗体，联合抗 SSA 和抗 SSB 可提高敏感性，而特异性无显著变化。
改良的 c2M3RP ELISA 是一种新型、敏感、特异的 SS 血清学检测方法。联合应用抗 c2M3RP、抗 SSA 和抗 SSB 检测可提高 SS 的实验室诊断。IgA 抗 c2M3RP 抗体可作为 SS 的一种新的诊断标志物。
