狼疮肾炎患者血清抗中性粒细胞胞浆抗体和靶抗原的研究

Antineutrophil cytoplasmic autoantibodies and their target antigens in Chinese patients with lupus nephritis

目的研究系统性红斑狼疮（ＳＬＥ）病人抗中性粒细胞胞浆抗体（ＡＮＣＡ）的阳性率及其特异性靶抗原。方法对９５例有肾活检资料的狼疮肾炎病人血清系统地应用间接免疫荧光法（ＩＦ）及抗原特异性ＥＬＩＳＡ法检测了ＡＮＣＡ。ＥＬＩＳＡ法应用的抗原为高度纯化的六种已知ＡＮＣＡ靶抗原：蛋白酶３（ＰＲ３）、髓过氧化物酶（ＭＰＯ）、杀菌／通透性增高蛋白（ＢＰＩ）、人白细胞弹力蛋白酶（ＨＬＥ）、组蛋白酶Ｇ（ＣＧ）和乳铁蛋白（ＬＦ），并比较肾活检的病理活动指标是否与ＡＮＣＡ相关。结果（１）无一例血清识别ＰＲ３、ＭＰＯ；仅１例识别ＢＰＩ；６２．１％（５９／９５）的ＳＬＥ病人血清识别ＣＧ，部分血清滴度可达１／３２００；少数血清识别ＬＦ（８／９５，８．４％）。（２）应用ＩＦ法，仅２２％为单纯ＡＮＣＡ阳性。（３）对抗ＣＧ抗体而言，肾脏病理有活动指标者的阳性率为７３．８％（４８／６５），而无活动病变者则为３６．７％（１１／３０），二者差异有极显著意义（χ２＝１２０５６，Ｐ＜０．０００１）；而抗ＬＦ抗体则与病变活动无相关。结论（１）多数狼疮肾炎患者血清中存在ＡＮＣＡ，ＣＧ为其主要靶抗原且抗ＣＧ抗体与肾脏病理活动相关，并进一步提示应重视抗胞浆抗体?

Objective To investigate the prevalence of ANCA and their target antigens in Chinese patients with lupus nephritis (LN) and to find the association between ANCA and active renal pathological lesions. Methods 95 serum samples were collected from 95 renal biopsy proven LN patients and indirect immunofluorescence (IIF) using ethanol fixed leukocytes as substrate and ELISA using six highly purified known ANCA antigens as solid phase ligands were performed. The specific ANCA antigens included proteinase 3 (PR3), myeloperoxidase (MPO), bactericidal/permeability increasing protein (BPI), human leukocyte elastase (HLE), cathepsin G (CG) and lactoferrin (LF). The prevalence of ANCA in patients with (n=65) and without (n=30) active renal pathological lesions were also compared to find whether ANCA were correlated with renal disease activities. Results (1) None of the sera recognized PR3 or MPO, only one serum recognized BPI. A striking finding was that 59/95 (62.1%) of the sera recognized CG and the titers of some sera could reach 1/3 200, 8/95 (8.4%) recognized LF. (2) By with IIF method, only 22% was ANCA positive. (3) the percentage of anti-CG positive samples in patients with active renal pathological lesions was significantly higher than that in patients without active lesions (73.8% vs 36.7%, P <0.0001), whereas, anti-LF antibodies had no correlation with active renal lesions. Conclusion Majority of the LN patients had ANCA and their target antigens was CG, and anti CG antibodies might be correlated with renal pathological activities. It is not reliable to detect ANCA with IIF method for ANA positive sera.