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Abstract: PO1470

Epitope Spreading and Immune Complex Rearrangement in Membranous Nephropathy

Session Information

Category: Glomerular Diseases

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Sogbein, Olusola, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States
  • Afrouzian, Marjan, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States
  • Kochar, Tina, The University of Texas Medical Branch at Galveston, Galveston, Texas, United States
Introduction

We present a rare case of ANA and anti-dsDNA negative, anti-GBM positive lupus nephritis (LN) patient with two biopsies demonstrating LN Class III+V with possible immune complex (IC) rearrangement and/or epitope spreading (ES).

Case Description

A 62-year-old white male who presented with a year-long history of purpuric rash and hematuria. His hospital admission laboratory data is detailed in Table 1. The first renal biopsy showed crescents in 2/4 glomeruli with mild (+) granular and segmentally linear deposits by immunofluorescence (IF). The patient received cyclophosphamide, corticosteroids and one session of therapeutic plasma exchange due to rapidly worsening renal function and an initial presumptive diagnosis of anti-GBM disease. The second biopsy demonstrated no crescents but features of combined class III + V LN with IF findings suggestive of a full-house pattern with a change in the deposits from segmentally linear to pure granular. He began therapy with mycophenolate mofetil and prednisone resulting in a decrease in his UPCR from 2.3 to 0.3 mg/mg (complete remission) over the next four months and significant improvement in renal function.

Discussion

A link has been reported between anti-GBM histopathology and membranous nephropathy. Evidence suggests IC rearrangement and/or ES as possible explanations. ES refers to the molecular conformational changes of secondary, non-dominant epitopes leading to propagation of autoimmunity. Circulating anti-GBM antibodies may continually stimulate the upregulation and alteration of anti-GBM epitopes leading to the development of granular deposits and membranous nephropathy. We believe our case suggests this possible pathogenic mechanism. More research is needed to improve understanding of the sequential change observed on immunofluorescence microscopy.

Laboratory Data
Laboratory TestResultUnitsReference Interval
White Blood Count8.3x10 3 /mL4.0-10.5
Hemoglobin12.8g/dL14.0-18.0
Platelets342x10 3 /mL140-415
Creatinine2.35mg/dL0.7-1.3
Complement - C339mg/dL88-201
Complement - C42mg/dL15-45
Anti-Neutrophil Antibody (ANA)1:20 Titer < 1:40 (negative)
Double Stranded DNA Antibody (dsDNA Ab)3.0IU/mL<30.0
Anti-Glomerular Basement Membrane (anti-GBM)63AU/mL0-19
Urine Protein-to-Creatinine Ratio (UPCR)2.3mg/mg<0.2