Dalmas Paul, Bobot Mickael, Jourde-Chiche Noémie, Bruno Julie, Burtey Stéphane, Daniel Laurent, El-Sissy Carine, Fremeaux-Bacchi Véronique, Jorquera Antonio, Javaugue Vincent, Schleinitz Nicolas, Ebbo Mikael
Aix-Marseille Univ, APHM, hôpital de la Timone, Internal Medicine Department, Marseille, France.
C2VN, INSERM, INRAE, Aix-Marseille Université, Marseille, France.
Kidney Med. 2025 May 3;7(7):101019. doi: 10.1016/j.xkme.2025.101019. eCollection 2025 Jul.
C3 glomerulonephritis (C3GN) is characterized by glomerular aggression mediated by deregulation of the alternative complement pathway. C3GN can be inherited or consequent to acquired autoantibodies, notably against factor H. We report the case of a patient with systemic active IgG4-related disease who presented for acute kidney injury with glomerular proteinuria and hypocomplementemia related to C3GN associated with IgG4-related interstitial nephritis on kidney biopsy. Factor H was low, and antifactor H IgG autoantibody was detected. Detection of other acquired or genetic complement alternative pathway disorders returned negative. After initial failure of oral corticoids and intravenous rituximab, the patient was successfully treated by intravenous cyclophosphamide followed by maintenance therapy with rituximab. Antifactor H autoantibody isotypes were IgG1 and IgG3, mainly as all antifactor H in positive controls but also IgG4, which is unusual. This suggests a link in this case between the oligoclonal expansion of plasma cells in IgG4-related disease and the production of antifactor H antibodies, especially of IgG4 isotype.
C3肾小球肾炎（C3GN）的特征是由替代补体途径失调介导的肾小球侵袭。C3GN可以是遗传性的，也可以是由获得性自身抗体引起的，尤其是针对H因子的自身抗体。我们报告了一例系统性活动性IgG4相关疾病患者，该患者因急性肾损伤就诊，伴有肾小球蛋白尿和低补体血症，肾活检显示与IgG4相关间质性肾炎相关的C3GN。H因子水平低，并检测到抗H因子IgG自身抗体。其他获得性或遗传性补体替代途径疾病的检测结果均为阴性。在口服皮质类固醇和静脉注射利妥昔单抗初始治疗失败后，患者通过静脉注射环磷酰胺成功治疗，随后用利妥昔单抗维持治疗。抗H因子自身抗体的同种型为IgG1和IgG3，主要与阳性对照中的所有抗H因子相同，但也有IgG4，这是不寻常的。这表明在该病例中，IgG4相关疾病中浆细胞的寡克隆扩增与抗H因子抗体的产生之间存在联系，尤其是IgG4同种型。
