BACKGROUND We investigated the characteristics of antineutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (ANCA-GN) and immunoglobulin G4 (IgG4)-related kidney disease (IgG4-RKD) overlap syndrome. METHODS This is a 2-center study with 19 patients. RESULTS Fifteen patients were classified as microscopic polyangiitis (MPA). The initial serum creatinine levels were 320.9 ± 191.4 μmol/l and the BVAS was 19.7 ± 7.4 at diagnosis. Hematuria was absent or slight in 13 (68.4%) cases. Renal histology of these patients revealed concurrent ANCA-GN and IgG4-RKD. Regarding the histological classification of ANCA-GN, 9 (47.4%), 8 (42.1%), 1 (5.3%) and 1 (5.3%) patients were classified as focal, crescentic, mixed and sclerotic ANCA-GN, respectively. MPO-ANCA could be detected in 17/19 (89.5%) patients. IgG subclasses of MPO-ANCA were tested in 10 patients, and all were positive for IgG4-MPO-ANCA. In patients with combined ANCA-GN and IgG4-RKD, the percentage of positive IgG1-MPO-ANCA was significantly lower than the control group of 20 AAV patients without IgG4-RKD (P = 0.002), and the percentage of positive IgG4-MPO-ANCA was higher than the control group, but this difference was not statistically significant (P = 0.14). CONCLUSIONS ANCA-GN and IgG4-RKD overlap syndrome concerned mainly MPO-ANCA positive patients. The IgG subclass analysis of MPO-ANCA showed lower percentage of IgG1 subclass. The association between ANCA-GN and IgG4-RKD is possible and represents a special entity.

中文翻译：

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抗中性粒细胞胞浆抗体（ANCA）相关的肾小球肾炎和IgG4相关的肾脏疾病的重叠。

背景我们研究了抗中性粒细胞胞浆抗体（ANCA）相关的肾小球肾炎（ANCA-GN）和免疫球蛋白G4（IgG4）相关的肾脏疾病（IgG4-RKD）重叠综合征的特征。方法这是一项针对19位患者的2中心研究。结果15例患者被归类为镜下性多血管炎（MPA）。诊断时初始血清肌酐水平为320.9±191.4μmol/ l，BVAS为19.7±7.4。13例（68.4％）无血尿或轻度。这些患者的肾脏组织学检查显示并发ANCA-GN和IgG4-RKD。关于ANCA-GN的组织学分类，分别将9例（47.4％），8例（42.1％），1例（5.3％）和1例（5.3％）分为局灶性，新月体，混合型和硬化性ANCA-GN。在17/19（89.5％）患者中可以检测到MPO-ANCA。在10例患者中测试了MPO-ANCA的IgG亚类，所有IgG4-MPO-ANCA均为阳性。在合并ANCA-GN和IgG4-RKD的患者中，IgG1-MPO-ANCA阳性的百分比显着低于对照组的20例无IgG4-RKD的AAV患者（P = 0.002）和IgG4-MPO阳性的百分比-ANCA高于对照组，但差异无统计学意义（P = 0.14）。结论ANCA-GN和IgG4-RKD重叠综合征主要涉及MPO-ANCA阳性患者。MPO-ANCA的IgG亚类分析显示IgG1亚类的百分比较低。ANCA-GN和IgG4-RKD之间的关联是可能的，并且代表一个特殊的实体。20例无IgG4-RKD的AAV患者中IgG1-MPO-ANCA阳性的百分比显着低于对照组（P = 0.002），而IgG4-MPO-ANCA阳性的百分比高于对照组，但是这一差异差异无统计学意义（P = 0.14）。结论ANCA-GN和IgG4-RKD重叠综合征主要涉及MPO-ANCA阳性患者。MPO-ANCA的IgG亚类分析显示，IgG1亚类的百分比较低。ANCA-GN和IgG4-RKD之间的关联是可能的，并且代表一个特殊的实体。20例无IgG4-RKD的AAV患者中IgG1-MPO-ANCA阳性的百分比显着低于对照组（P = 0.002），而IgG4-MPO-ANCA阳性的百分比高于对照组，但是这一差异差异无统计学意义（P = 0.14）。结论ANCA-GN和IgG4-RKD重叠综合征主要涉及MPO-ANCA阳性患者。MPO-ANCA的IgG亚类分析显示，IgG1亚类的百分比较低。ANCA-GN和IgG4-RKD之间的关联是可能的，并且代表一个特殊的实体。结论ANCA-GN和IgG4-RKD重叠综合征主要涉及MPO-ANCA阳性患者。MPO-ANCA的IgG亚类分析显示，IgG1亚类的百分比较低。ANCA-GN和IgG4-RKD之间的关联是可能的，并且代表一个特殊的实体。结论ANCA-GN和IgG4-RKD重叠综合征主要涉及MPO-ANCA阳性患者。MPO-ANCA的IgG亚类分析显示，IgG1亚类的百分比较低。ANCA-GN和IgG4-RKD之间的关联是可能的，并且代表一个特殊的实体。