抗双链DNA抗体IgG的亲合力及亚类在狼疮性肾炎疾病中的分布情况及作用初探

Preliminary analysis of distribution and effect on IgG avidity and subclass of anti double-stranded DNA antibody in lupus nephritis

目的探讨抗双链DNA（dsDNA）抗体IgG的亲合力及亚类在狼疮性肾炎（LN）疾病患者中的分布情况以及与肾脏受累之间的关系。方法病例对照研究。选择2012年2月至2014年5月于北京大学第一医院就诊，初次诊断为LN的148例患者进行研究，其中91例为肾脏内科住院患者，行肾脏活检穿刺术。用酶联免疫吸附法检测受试者血清IgG型抗dsDNA抗体亲合力及亚类。以。肾脏活检结果作为LN肾脏受累分级的依据。记录受试者。肾脏病理分级、肾脏病理活动性指数（AI）、慢性指数（CI）、系统性红斑狼疮疾病活动度评分（SLEDAI）评分以及其他各项实验室检查包括外周血白细胞计数、尿红细胞计数、尿蛋白定量、血肌酐、血清c3等系统性红斑狼疮（SLE）疾病活动度的指标，与受试者抗dsDNAIgG抗体亲合力、亚类等进行Spearman相关性分析。结果LN患者的抗dsDNA抗体亲合力指数中位数水平为33．7（19．2～51．1）。针对抗dsDNA抗体酶联免疫吸附法阳性患者，间接免疫荧光法阳性组的亲合力指数要显著高于间接免疫荧光法阴性组（H=15．13，P=0．0001）。抗dsDNA抗体以IgG3亚类为主（24例，26．4％），其次为4种亚类同时阳性（10例，11．0％）。将抗dsDNA抗体亲合力及亚类与各项肾脏受累指标及其他实验室指标做相关分析，抗dsDNA抗体亲合力与所有指标均不相关，IgG3亚类与肾脏活动性指数AI呈明显负相关（R=-0．42，P=0．03）。结论抗dsDNA抗体IgG的亲合力与LN肾脏受累不相关，IgG3亚类是LN患者的主要亚类，与肾脏的活动性指数明显相关，有可能作为LN肾脏受累的间接证据应用于临床。

Objective The aim of this study was to estimate the distribution and effect of anti dsDNA antibody on avidity and IgG subclass in lupus nephritis （LN）. Methods Case control study. A total of 148 patients first diagnosed as LN was enrolled from February 2012 to May 2014. 91 patients in renal department received renal biopsy. The avidity as well as IgG subclass of anti dsDNA antibody in serum were detected by ELISA. Renal involvements were classified according to the pathological results. The disease activity, including white blood cell count, urinary red blood cell count, urinary protein, serum ereatinine, C3, SLEDAI score, and pathology activity index （AI）, chronicity index （CI） was recorded. The relationship between activity and avidity as well as IgG subclass was assessed by Spearman correlation. Results Avidity index of anti-dsDNA IgG antibody in LN patients was 33.7 （ 19. 2 - 51.1 ）. It was higher in IIF positive group than in IIF negative group （ H = 15.13, P = 0. 0001 ）. Anti-dsDNA IgG3 （24 cases, 26. 4% ） was the predominant subclass, followed by all of four subclasses positive （ 10 cases, 11.0% ）. Anti-dsDNA antibody avidity was not associated with any indicator. IgG3 subclass was correlated with AI negatively （ R = -0. 42, P = 0. 03 ）. Conclusions IgG avidity of anti-dsDNA antibody was not related with renal involvement. IgG3 is the nmin subclass of LN patients and associated with pathology AI. IgG3 can be used as an indirect indicator of renal involvement in LN.