抗肾小球基底膜病患者血清自身抗体的异质性及其临床病例的相关性分析

目曲:研究抗肾小球基底膜(glomemlar basement membrane,GBM)病患者血清自身抗体的异质性及其临床病理的相关性.方珐:选取北京大学第一医院肾内科1991年1月至2009年5月收治的有完整临床及肾活检资料的108例抗GBM病患者为研究对象.收集就诊时的血清或血浆置换液用于孵育正常人肾组织冰冻切片行间接免疫荧光检查.隐匿性抗原表位的暴露采用6 mol/L尿素对组织切片进行预处理.天然抗原表位的检测则以未经处理的组织切片作为底物.抗体滴度的检测由1:2至1:512.根据间接免疫荧光的结果决定抗体是否识别不同抗原表位,并进一步分析识别不同抗原表位与临床表现的相关性.结果:108例患者血清或血浆置换液均识别隐匿性抗原表位(尿素处理后肾组织),问接荧光显示抗体沿GBM呈线条样沉积,其中56/108例(A组)也识别天然暴露的抗原表位(非处理肾组织),其余52/108例(B组)则不识别天然暴露的抗原表位.虽然A组血清可识别天然露的抗原表位,但是该组血清识别隐匿性表位的平均滴度明显高于B组(P＜0.01);A组患者合并抗中性粒细雕胞浆抗体(anti-neutrophil cytoplasmic antibodies,ANCA)的比例则明显低于B组(P＜0.01).两组患者就诊时的其他临床指标(包括血肌酐水平)和肾病理指标差异则无统计学意义.结论:所有患者血清抗GBM抗体识别GBM上隐匿的抗原表位,但近一半患者的抗体同时识别天然暴露的抗原表位.识别天然暴露抗原表位者其血清识别隐匿性抗原的滴度更高,血清ANCA阳性的几率显著减少.

The heterogeneity of anti-GBM autoantibodies in sera from patients with anti-GBM disease and its clinical correlation

Objective:To investigate the heterogeneity of epitopes recognized by anti-GBM autoantibodies in sera from a large cohort of Chinese patients with anti-GBM disease and its clinical significance.Methods: The present study included 108 patients with anti-GBM disease who were diagnosed in our hospital, between Jan 1991 and May 2009, with complete clinical and renal pathological data. Sera or plasma exchange of the patients were used to incubate with cryostat section of normal human renal tissue for indirect immunofluorescence (IIF) assay. The cryostat sections of normal renal tissue were pre-treated by 6 mol/L urea to unmask cryptic epitopes, and untreated cryostat sections were used to detect natural exposed epitopes. The sera were diluted from 1:2 to 1:512 to determine titers of anti-GBM autoantibodies Patients with anti-GBM autoantibodies against cryptic or exposed epitopes were further stratified;their clinical and pathological associations were analyzed. Results: Sera from all the 108 patients could recognize cryptic epitopes on normal renal tissue ( urea treated section). IIF showed IgG linear staining along GBM. However, sera from 56/108 patients (group A) could also recognize exposed epitopes on normal renal tissue (untreated section) ; sera from the rest 52/108 patients (group B) could not recognize exposed epitopes. In urea treated condition, the average titer of anti-GBM autoantibodies from sera of patients in group A was significantly higher than that in group B (P＜0.01) , ANCA-positive patients in group A were significant less than that in group B (P＜0.01) . There was no significant difference between the two groups in regard to other clinical data (including serum creatinine) and renal histopathologic data. Conclusion: Anti-GBM autoantibodies from some patients with anti-GBM disease could recognize natural exposed epitopes, however, their anti-GBM titer for cryptic epitopes was higher than that of those recognizing cryptic epitopes only and the prevalence of serum ANCA was significantly less.