Department of Cardiovascular and Internal Medicine, Division of Rheumatology, Kanazawa University Graduates School of Medicine, Kanazawa, Japan.
Department of Internal Medicine, Division of Rheumatology, Kanazawa University Hospital, Kanazawa, Japan.
Mod Rheumatol. 2021 Jan;31(1):241-248. doi: 10.1080/14397595.2019.1709942. Epub 2020 Jan 13.
This study investigated the clinical features of IgG4-RKD patients with hypocomplementemia compared with those without it, so as to clarify the factors related to hypocomplementemia.
In this single-center retrospective study, we analyzed the clinical features of 25 patients with IgG4-RKD according to the presence/absence of hypocomplementemia. Additionally, we validated the results of a single-center study in a separate large multicenter cohort of 328 patients with IgG4-RD, and searched for factors related to hypocomplementemia.
Serum IgG levels ( < .001), non-IgG4 IgG levels, calculated as the total IgG minus IgG4 ( < .001), serum IgG1 levels ( = .017), and the number of involved organs ( = .018) were significantly higher in the hypocomplementemia group. At relapse of renal lesions in four patients, all had serum IgG4 re-elevation, with the three with hypocomplementemia presenting worsening of hypocomplementemia and re-elevation of non-IgG4 IgG levels. In a validation cohort of 328 patients with IgG4-RD, multivariate logistic regression analysis indicated elevation of non-IgG4 IgG levels to be an independent factor related to hypocomplementemia in the patients with IgG4-RKD.
The present study suggests that hypocomplementemia is associated with elevation of IgG subclasses other than IgG4 including IgG1 in IgG4-RKD.
本研究旨在比较 IgG4-RKD 患者伴低补体血症与不伴低补体血症的临床特征，以阐明与低补体血症相关的因素。
在这项单中心回顾性研究中，我们根据 IgG4-RKD 患者是否存在低补体血症，分析了 25 例患者的临床特征。此外，我们还在 IgG4-RD 的另一项独立大型多中心队列 328 例患者中验证了单中心研究的结果，并寻找与低补体血症相关的因素。
低补体血症组血清 IgG 水平（ < .001）、非 IgG4 IgG 水平（计算方法为总 IgG 减去 IgG4， < .001）、血清 IgG1 水平（ = .017）和受累器官数（ = .018）显著升高。在四名患者的肾脏病变复发时，所有患者的血清 IgG4 均再次升高，其中 3 名低补体血症患者的低补体血症恶化且非 IgG4 IgG 水平再次升高。在 IgG4-RD 的 328 例验证队列中，多变量逻辑回归分析表明，非 IgG4 IgG 水平升高是 IgG4-RKD 患者低补体血症的独立相关因素。
本研究提示 IgG4-RKD 患者的低补体血症与 IgG4 以外的 IgG 亚类升高有关，包括 IgG1。
