The current study aimed to analyze the clinical significance and bio-functional properties of anti-C3b IgG based on a lupus nephritis cohort. We found that the prevalence of anti-C3b IgG in our cohort was 47.8%. Patients with positive anti-C3b IgG had significantly higher SLEDAI, lower circulating C3 and C4 levels. Anti-C3b IgG levels were positively correlated with C3 or C1q deposition in kidneys and several active pathological lesions. The positivity of anti-C3b IgG was an independent risk factor for the composite endpoints in the subgroup of proliferative lupus nephritis patients. In vitro, the purified IgG fractions from positive patients resulted in increased C3a generation through the alternative pathway, and interfered factor H and CR1 binding to C3b. Our findings indicated that anti-C3b IgG associated with local renal injury and long-term outcomes in lupus nephritis patients, possibly through leading to the complement alternative pathway over-activation.

本研究旨在分析基于狼疮性肾炎队列的抗C3b IgG的临床意义和生物功能特性。我们发现在我们的队列中抗C3b IgG的患病率为47.8％。抗C3b IgG阳性的患者的SLEDAI明显较高，循环C3和C4水平较低。抗C3b IgG水平与肾脏和一些活动性病理病变中的C3或C1q沉积呈正相关。抗C3b IgG的阳性是增生性狼疮肾炎患者亚组中复合终点的独立危险因素。在体外，来自阳性患者的纯化IgG馏分通过替代途径导致C3a生成增加，并干扰了H因子和CR1与C3b的结合。