Laboratory of Molecular Immunopathology and Department of Medical Pathology, Federal University of Paraná, Curitiba, Brazil.
Hum Immunol. 2013 Aug;74(8):907-10. doi: 10.1016/j.humimm.2013.04.030. Epub 2013 Apr 29.
BACKGROUND/AIMS: Lupus nephritis (LN) is one of the most serious manifestations of SLE occurring in 66-90% of these patients. The complement system is part of the innate immunity and modulator of inflammation and the adaptative immune response. Mannan-binding lectin (MBL) and Ficolin-2 (FCN-2) are important members of the lectin pathway of complement activation. Despite the significant participation of complement in the pathogenesis of the LN, there are few reports demonstrating "in situ" deposition of complement components in renal biopsy specimens in this disorder. The present study investigated the deposition of complement components in kidney specimens of LN patients.
Renal biopsies of 11 patients with SLE and LN were evaluated for immunofluorescence staining for IgG, IgA, IgM, C3, and C1q. Additionally, MBL, FCN-2 and C5b-9 were researched using monoclonal antibodies.
All the biopsies were positive for IgG, C3, and C1q, eight were positive IgM and five had IgA deposition in glomerular tissue. The terminal complex of complement C5b9 was positive in all cases, MBL in nine (82%) cases; seven (63.6%) of them presenting concomitantly FCN-2 deposition. Patients presenting MBL deposition had higher mean of urinary proteins (9.0 g/day) than patients with negative MBL deposition (mean of 2.3g/day).
In this study, we demonstrated in situ the participation of complement in the renal injury, including MBL and FCN-2 of the lectin pathway; also the strong role of C5b-9 in the pathogenesis of LN.
背景/目的：狼疮肾炎（LN）是系统性红斑狼疮（SLE）最严重的表现之一，发生在 66-90%的患者中。补体系统是先天免疫的一部分，调节炎症和适应性免疫反应。甘露聚糖结合凝集素（MBL）和纤维胶凝素-2（FCN-2）是补体激活凝集素途径的重要成员。尽管补体在 LN 的发病机制中具有重要作用，但很少有报道证明在该疾病的肾活检标本中存在补体成分的“原位”沉积。本研究调查了 LN 患者肾组织标本中补体成分的沉积情况。
对 11 例 SLE 合并 LN 患者的肾活检标本进行免疫荧光染色，检测 IgG、IgA、IgM、C3 和 C1q。此外，还使用单克隆抗体研究了 MBL、FCN-2 和 C5b-9。
所有活检标本均为 IgG、C3 和 C1q 阳性，8 例 IgM 阳性，5 例 IgA 阳性。所有病例均有补体末端复合物 C5b9 阳性，9 例（82%）有 MBL 阳性，7 例（63.6%）同时有 FCN-2 阳性。有 MBL 沉积的患者尿蛋白平均值（9.0g/天）高于无 MBL 沉积的患者（平均值 2.3g/天）。
本研究在 LN 患者的肾损伤中证明了补体的参与，包括凝集素途径的 MBL 和 FCN-2；还证明了 C5b-9 在 LN 发病机制中的重要作用。
