From the Department of Pathology and Laboratory Medicine, University of California Davis School of Medicine, Sacramento (Dr Cheng); and the Department of Pathology and Translational Pathobiology, Louisiana State University Health Sciences Center, Shreveport (Drs Gu, Turbat-Herrera, and Herrera).
Arch Pathol Lab Med. 2019 Oct;143(10):1212-1224. doi: 10.5858/arpa.2018-0032-OA. Epub 2019 May 7.
CONTEXT.—: Light chain-associated acute tubulointerstitial nephritis (LC-ATIN) is a variant of light chain proximal tubulopathy (LCPT). It is characterized by interstitial inflammation with tubulitis and deposition of monoclonal light chains in the tubulointerstitium. LC-ATIN is a rather poorly recognized pattern of LCPT and not much is known about this entity.
OBJECTIVE.—: To determine the clinicopathologic features of patients with LC-ATIN and investigate the proximal tubular injury and mechanism of interstitial inflammation in LC-ATIN.
DESIGN.—: A total of 38 cases of LC-ATIN were identified from the archives of 5043 renal biopsy specimens. In all cases, routine light microscopic examination, immunofluorescence, and electron microscopic examination were performed. In selected cases, immunofluorescent staining of dendritic cells and immunohistochemical staining for 4 tubular injury markers-KIM-1, p53, bcl-2, and Ki-67-were performed.
RESULTS.—: A characteristic finding in LC-ATIN cases was immunofluorescence staining of monoclonal light chains along tubular basement membranes in linear fashion and inside proximal tubular cells with a granular pattern. No monoclonal light chains were present in glomerular or vascular compartments confirmed with immunofluorescence, electron microscopy, and ultrastructural gold labeling. Ten of 15 LC-ATIN cases (67%) were concurrently positive for the 4 tubular injury markers. Dendritic cells were identified within the tubulointerstitium in the renal biopsy specimens, interacting with surrounding tubules with light-chain deposits and inflammatory cells.
CONCLUSIONS.—: Significant proximal tubular injury occurs associated with LC-ATIN, and the monoclonal light chains accumulated in proximal tubular cells contribute to the injury. Dendritic cells are involved in the pathogenesis of interstitial inflammation in LC-ATIN.
轻链相关性急性肾小管间质性肾炎（LC-ATIN）是轻链近端肾小管病变（LCPT）的一种变体。其特征为间质炎症伴有肾小管炎和单克隆轻链在肾小管间质中的沉积。LC-ATIN 是 LCPT 中一种相对不太被认识的形式，对于这种疾病知之甚少。
确定 LC-ATIN 患者的临床病理特征，并研究 LC-ATIN 中近端肾小管损伤和间质炎症的机制。
从 5043 例肾活检标本的档案中确定了 38 例 LC-ATIN 病例。所有病例均进行了常规光镜检查、免疫荧光检查和电镜检查。在选定的病例中，进行了树突状细胞的免疫荧光染色和 4 种管状损伤标志物-KIM-1、p53、bcl-2 和 Ki-67-的免疫组织化学染色。
LC-ATIN 病例的一个特征性发现是免疫荧光染色显示单克隆轻链沿肾小管基底膜呈线性排列，在近端肾小管细胞内呈颗粒状。免疫荧光、电子显微镜和超微结构金标记均证实肾小球或血管间隙内无单克隆轻链。15 例 LC-ATIN 病例中有 10 例（67%）同时对 4 种管状损伤标志物呈阳性。在肾活检标本中鉴定出肾小管间质内的树突状细胞，与周围带有轻链沉积和炎症细胞的肾小管相互作用。
LC-ATIN 存在明显的近端肾小管损伤，蓄积在近端肾小管细胞内的单克隆轻链导致损伤。树突状细胞参与 LC-ATIN 间质炎症的发病机制。
