Yarandi Niloufarsadat, Alexander Mariam P, Nasr Samih H, Leung Nelson
Department of Internal Medicine, Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN.
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN.
Kidney Med. 2022 Jun 28;4(8):100514. doi: 10.1016/j.xkme.2022.100514. eCollection 2022 Aug.
Heavy/light chain (HLC) antibodies can be used to quantify intact HLC pairs. In immunofluorescence studies, they allow differentiation of monoclonal versus polyclonal immunoglobulin deposits in kidney diseases that occur in the setting of monoclonal gammopathy. Here, we present a case of a patient with acute kidney injury with first kidney biopsy suggestive of acute interstitial nephritis with a polymorphous infiltrate of plasma cells. Routine immunofluorescence did not show a monotypic plasma cell infiltrate. Serum protein electrophoresis and immunofixation revealed monoclonal immunoglobulin A (IgA) lambda. She improved with steroid therapy, but kidney function worsened after steroids were stopped. She underwent a second kidney biopsy, which showed plasma cell-rich interstitial infiltrate with a population of IgA lambda-restricted plasma cells on routine immunofluorescence. In light of this finding, Hevylite HLC antibody was used to reassess the first biopsy, which confirmed the presence of a population of plasma cells with IgA lambda restriction. Because of the presence of monotypic plasma cells, anti-CD38 monoclonal antibody (daratumumab) was initiated.
重链/轻链（HLC）抗体可用于定量完整的HLC对。在免疫荧光研究中，它们有助于区分在单克隆丙种球蛋白病背景下发生的肾脏疾病中的单克隆与多克隆免疫球蛋白沉积物。在此，我们报告一例急性肾损伤患者，首次肾脏活检提示急性间质性肾炎伴浆细胞多形性浸润。常规免疫荧光未显示单型浆细胞浸润。血清蛋白电泳和免疫固定显示单克隆免疫球蛋白A（IgA）λ。她接受类固醇治疗后病情改善，但停用类固醇后肾功能恶化。她接受了第二次肾脏活检，常规免疫荧光显示富含浆细胞的间质浸润，其中一群浆细胞受IgA λ限制。鉴于这一发现，使用Hevylite HLC抗体重新评估首次活检，证实存在一群受IgA λ限制的浆细胞。由于存在单型浆细胞，开始使用抗CD38单克隆抗体（达雷妥尤单抗）。
