酶联免疫吸附测定法检测抗髓过氧化物酶IgG亚型分布及其临床意义

目的：观察抗髓过氧化物酶（MPO）IgG各亚型（IgG1、IgG2、IgG3、IgG4)在小血管炎患者的分布及其与临床病情的关系,以探讨IgG亚型是否能更准确地反映病情变化。方法：选取30例抗MPO抗体阳性的原发性小血管炎患者,对其活动期和缓解期血清采用抗原特异性ELISA法分别测定活动期抗MPO IgG各亚型的阳性率及缓解期的转阴率,并与抗中性粒细胞胞质抗体（ANCA）总IgG的变化进行对比。结果：临床活动期抗MPO－ANCA IgG的4种亚型均为阳性,以IgG4最高;而缓解期以IgG1和IgG3下降为著,其中IgG3的转阴率最高,且显著高于总IgG。结论：IgG3的变化与病情活动密切相关,在一定程度上可以代替总IgG监测病情的发展。IgG4在疾病的活动期与缓解期都显著增高,可能与反复的抗原刺激和慢性的免疫反应有关。

The relationship between subclassification of anti-myeloperoxidase IgG by enzyme-linked immuno-sorbent assay analysis and vasculitis activity

OBJECTIVE: Antineutrophil cytoplasmic antibody (ANCA) is an important serological diagnostic tool for certain vasculitides, such as Wegener's granulomatosis and microscopic polyangiitis. Several studies suggested that ANCA titers correlated with disease activity. However, in some patients, ANCA still remained positive when patients were in clinical remission. The major isotype of ANCA is IgG, which has four subclasses. This study is to investigate the relationship between anti-MPO IgG subclasses and vasculitis activity. METHODS: Serum samples, taken from 30 anti-myeloperoxidase (MPO) antibody positive patients both in active phase and in remission, were analysed by ELISA for their anti-MPO IgG subclass distribution and the change of anti-MPO IgG subclasses was compared with the change of anti-MPO IgG antibodies. RESULTS: All four anti-MPO IgG subclasses were positive in active phase, IgG(4) being the highest. In remission, the level of anti-MPO IgG(1) and IgG(3) subclasses decreased the most and the percentage of negative change of IgG(3) was the highest, even more significant than that of the total IgG. CONCLUSION: anti-MPO IgG(3) antibody is more closely related with clinical disease activity than the total IgG. Higher ratio of IgG(4) may suggest that chronic repeated antigen stimuli may play a role in the production of ANCA.