Abstract: FR-OR89
Detection and Characterization of NELL1 Autoantibodies in NELL1-Positive Membranous Nephropathy
Session Information
- Pathology and Lab Medicine Advances
October 25, 2024 | Location: Room 2, Convention Center
Abstract Time: 05:40 PM - 05:50 PM
Category: Pathology and Lab Medicine
- 1800 Pathology and Lab Medicine
Authors
- Caza, Tiffany, Arkana Laboratories, Little Rock, Arkansas, United States
- Arivett, Brock A., Meharry Medical College, Nashville, Tennessee, United States
- Hassen, Samar, Arkana Laboratories, Little Rock, Arkansas, United States
- Larsen, Christopher Patrick, Arkana Laboratories, Little Rock, Arkansas, United States
- Borza, Dorin-Bogdan, Meharry Medical College, Nashville, Tennessee, United States
Background
Discovery of novel autoantigens in membranous nephropathy (MN) holds promise for development of serologic tests to monitor disease activity and guide treatment. Neural epidermal growth factor-like 1 (NELL1) is the second most common antigen in MN. Anti-NELL1 antibodies are currently detected within patient sera by western blotting against NELL1 recombinant protein, but no reproducible, high-throughput clinical assay is yet available.
Methods
Serum samples from 29 patients with NELL1 MN, 33 with PLA2R MN, and 25 healthy controls were collected. Samples were not obtained at the time of biopsy and serologic remission cannot be entirely excluded. We developed a quantitative enzyme-linked immunosorbent assay (ELISA) for NELL1 antibodies using a NELL1 recombinant protein as an antigen source and an indirect immunofluorescence assay for detection of anti-NELL1 antibodies using HEK-293 cells stably transfected with a NELL1-FLAG plasmid vector. IgG subclasses were examined within sera and tissue using subclass specific antibodies.
Results
We detected antibodies within patient sera against NELL1 in 16/33 NELL1 samples and 3/61 controls by ELISA with a sensitivity of 55.2% and specificity of 95.1%. Circulating anti-NELL1 antibodies were predominantly IgG1 and IgG4, with IgG1 antibodies present within all positive samples. Sensitivity of the indirect immunofluorescence assay was 71.4% and specificity 98.6%. Western blots were performed in a subset of cases with good concordance of results between all three methods.
Conclusion
Our data provide methods for serologic testing that can be utilized for serologic evaluation of NELL1-associated MN. High specificity was achieved (95.1-98.6%), however sensitivity was low, which could be due to patients being in serologic remission at the time of serum collection. Further work will establish if antibody titers correlate with disease activity and response to immunosuppressive therapy.
Funding
- NIDDK Support