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Abstract: PO1940

Anti-Brush Border Antibody Disease with Nephrotic Syndrome: A Clinicopathologic Analysis of Five Cases

Session Information

Category: Pathology and Lab Medicine

  • 1600 Pathology and Lab Medicine

Authors

  • Zhu, Xiaoye, Huashan Hospital Fudan University, Shanghai, Shanghai, China
  • Liu, Shaojun, Huashan Hospital Fudan University, Shanghai, Shanghai, China
  • Xue, Jun, Huashan Hospital Fudan University, Shanghai, Shanghai, China
  • Hao, Chuan-Ming, Huashan Hospital Fudan University, Shanghai, Shanghai, China
Background

Anti-brush border antibody(ABBA)disease is a recently described etiology of acute kidney injury and progressive renal tubular injury that mainly affects the older patients. ABBA is characterized by the presence of circulating autoantibodies to the proximal tubular brush border protein LRP2(megalin)and IgG immune complex deposits along the basement membrane of proximal tubules. In the present study, we report 5 cases of ABBA that all presented as nephrotic proteinuria.

Methods

We retrospectively screened for ABBA disease through our renal biopsy cohort from January 2018 to May 2021.The anti-brush border antibody disease was diagnosed based on the presence of ABBA in the serum, showing positive ABBA on a kidney section by indirect immunofluorescence with patient’s serum, and kidney histology. Histology of the biopsies and clinical data were analyzed.

Results

Five cases with ABBA disease were identified, out of 0.1% total biopsies. Mean age was 41 years (29-54) with a M:F ratio of 1:4. At biopsy, all had nephrotic syndrome with proteinuria (12.1 g/24h, 3.8-27 g/24h). Only one patient presented with acute kidney injury. Serologies, including ANA, dsDNA, ANCA, anti-GBM were negative. C3 and C4 levels were normal. Neither acute tubular injury nor intensive Interstitial inflammation were found in all these biopsies. Proximal tubular brush border and glomerular basement membranes stained positive for IgG in all cases, and 3 cases also have positive deposits in some segments of TBM. Staining for IgG subclass showed that IgG1 was positive, while IgG2, IgG3 and IgG4 were not detected. Interestingly, we found light chain monotype of lambda in two patients. Electron microscopy showed diffuse podocyte foot process effacement in all cases. All patients received prednisone plus cyclophosphamide therapy and achieved complete recovery after 2 months (range: 1-3) (Table 1).

Conclusion

We report 5 cases of anti-ABBA disease with nephrotic syndrome recovered after treatment with prednisone and cyclophosphamide. The mechanism of podocyte injury in anti-ABBA disease requires additional studies.