Abstract: SA-PO691
Immunostaining for Galactose-Deficient IgA1 in Routine Kidney Biopsies
Session Information
- Pathology and Lab Medicine: Clinical
November 09, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Pathology and Lab Medicine
- 1602 Pathology and Lab Medicine: Clinical
Authors
- Becker, Jan U., University Hospital Cologne, Köln, NW, Germany
- Hoppe, Bernd, University Hospital Bonn, Bonn, Germany
- Mueller, Roman-Ulrich, Dept. 2 of Internal Medicine, University of Cologne, Koeln, Germany
- Hoyer, Peter, University Hospital Essen, Essen, Germany
Background
Recently, an antibody against galactose-deficient IgA1 (gdIgA1) became commercially available. Very little is known about the specific staining patterns of this KM55 antibody in routine diagnostics. Here we report the staining pattern in routine native and transplant biopsies with various forms of IgA-codominant glomerulonephritis and controls.
Methods
We established a protocol for formalin-fixated paraffin embedded (FFPE) tissue with protease antigen retrieval (Fast Enzyme, Zytomed Systems, Germany). Primary antibody KM55 was incubated overnight at 1:5 dilution and visualized with a standard peroxidase system and reported as 0, 1+, 2+, 3+ on 58 consecutive renal biopsies with IgA-codominant glomerular staining (50 native, 8 transplant) and controls (7 IgM glomerulopathy, 3 infectious associated glomerulonephritis) together with immunostaining for IgA1 and IgA2.
Results
26/43 (60%) primary IgA-GN (pIgA-GN), 7/9 (78%) Henoch-Schönlein Purpura (HSP) and 2/4 (50%) cirrhotic IgA-GN (cirrhIgA-GN), 0/1 (0%) staphylococcus-associated GN (staphGN), 0/1 (0%) monoclonal IgA-GN were positive for gdIgA1. IgA1 was dominant over IgA2 in 40/43 pIgA-GN, 7/9 (78%) HSP, 4/4 (100%) cirrhIgA-GN, 1/1 (100%) staphGN; IgA2 over IgA1 in 1/43 (2%) pIgA-GN, 0/9 (0%) HSP and 0/4 (0%) cirrhIgA-GN. gdIgA1 was negative in all controls. Repeat biopsies in transplants showed consistent staining.
Conclusion
We report an immunohistochemical staining method for gdIgA on FFPE kidney biopsies. Together with serum tests for gdIgA1 and anti-gdIgA1 autoantibodies, this ancillary staining method could be useful for a pathogenesis-driven classification of glomerular diseases with IgA-codominant deposits.
3+ mesangial staining (brown) for gdIgA1 in a FFPE biopsy which was classified as primary IgA-GN. Immunoperoxidase, original magnification x400.