Galactose-deficient immunoglobulin A1 (Gd-IgA1) was recently identified as a critical effector molecule in the pathogenesis of IgA nephropathy (IgAN). Gd-IgA1 is produced by the mucosal immune system. IgAN is thought to develop because of the deposition of a circulating immune-complex containing Gd-IgA1 in the kidney. Multicentric Castleman's disease (MCD) is a rare non-neoplastic lymphoproliferative disorder. As an etiology model, hypercytokinemia, including increased levels of interleukin-6, is the primary pathogenesis of many MCD cases. Here, we present two cases of mesangial proliferative glomerulonephritis with MCD. According to renal biopsy findings, one was diagnosed with non-IgAN and the other with IgAN. Surprisingly, in both cases, Gd-IgA1 was produced by plasma cells in the lymph nodes, suggesting that Gd-IgA1 production alone does not cause IgAN; rather, it may be produced without induction by mucosal immunity. Our findings demonstrate the diversity of the development of IgAN and help to reconsider the onset mechanism of IgAN.

中文翻译：

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肾小球系膜增生性肾小球肾炎合并多中心Castleman病的病例报告：免疫球蛋白A肾病发病机制的探讨。

半乳糖缺陷型免疫球蛋白A1（Gd-IgA1）最近被确定为IgA肾病（IgAN）发病机理中的关键效应分子。Gd-IgA1由粘膜免疫系统产生。人们认为IgAN的发展是由于肾脏中含有Gd-IgA1的循环免疫复合物的沉积。多中心Castleman病（MCD）是一种罕见的非肿瘤性淋巴增生性疾病。作为病因学模型，高细胞血症，包括白介素6水平升高，是许多MCD病例的主要发病机制。在这里，我们介绍了两例伴有MCD的系膜增生性肾小球肾炎。根据肾脏活检结果，其中一名被诊断为非IgAN，另一名被诊断为IgAN。令人惊讶的是，在两种情况下，Gd-IgA1都是由淋巴结内的浆细胞产生的，提示单独生产Gd-IgA1不会引起IgAN；而是可以不经粘膜免疫诱导而产生。我们的发现证明了IgAN的发展多样性，并有助于重新考虑IgAN的发病机制。