There is a great lack of efficient treatments for membranoproliferative glomerulonephritis (MPGN) and recently emerged complement therapies have been proposed to be useful. We report a patient with a complement-mediated MPGN having recurrencies in kidney allografts and an unsuccessful treatment with complement inhibitor, eculizumab (anti-C5 monoclonal antibody). Nephritic factor (C3Nef), an autoantibody against C3bBb, in the patient serum activated C3 but not C5 showing that major damage was mediated by C3 activation with clearly less involvement of C5 explaining unresponsiveness to eculizumab. Analyzing C3Nef-mediated C3 and C5 activation separately could help in choosing the right patients for eculizumab therapy.

膜增生性肾小球肾炎（MPGN）的有效治疗方法非常缺乏，并且最近提出的补体疗法被认为是有用的。我们报道了一名患有补体介导的MPGN的患者，该患者在同种异体肾移植中复发，并且使用补体抑制剂依库丽单抗（抗C5单克隆抗体）治疗失败。肾病因子（C3Nef）是一种抗C3bBb的自身抗体，在患者血清中激活了C3，但未激活C5，表明主要损害是由C3激活介导的，而C5的参与明显较少，说明对依库丽单抗无反应。分别分析C3Nef介导的C3和C5激活可能有助于选择合适的患者进行依库丽单抗治疗。