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Abstract: FR-PO812

A Novel ELISA Allows Exact PLA2R1 Domain-Specific Autoantibody Quantification in Sera from Patients with Membranous Nephropathy

Session Information

Category: Glomerular Diseases

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Reinhard, Linda, University Hospital Hamburg Eppendorf, Hamburg, Germany
  • Zahner, Gunther, University Hospital Hamburg Eppendorf, Hamburg, Germany
  • Menzel, Stephan, University Hospital Hamburg Eppendorf, Hamburg, Germany
  • Koch-nolte, Friedrich, University Hospital Hamburg Eppendorf, Hamburg, Germany
  • Stahl, Rolf A., University Hospital Hamburg Eppendorf, Hamburg, Germany
  • Hoxha, Elion, University Hospital Hamburg Eppendorf, Hamburg, Germany
Background

Phospholipase A2 Receptor 1 (PLA2R1) is the major antigen, which is recognized by autoantibodies in about 80% of patients with membranous nephropathy (MN). Total PLA2R1-antibody (PLA2R1-ab) levels are closely associated with disease prognosis and treatment response. The aim of the study was to investigate the clinical relevance of PLA2R1 domain-specific antibody levels in patients with PLA2R1-associated MN.

Methods

Individual CysR, CTLD1, CTLD7 and CTLD8 domains of the PLA2R1 were fused N-terminal to the rabbit Fc unit. The purified fusion proteins were used to establish novel PLA2R1 domain-specific ELISA. A prospective cohort of 149 untreated patients with newly-diagnosed PLA2R1-associated MN as well as a control cohort of 50 individuals (10 FSGS, 10 minimal change disease, 10 MPGN, 11 IgA nephropathy, 9 healthy donors) was analyzed. Results were validated using Western blot techniques.

Results

The ELISAs of the N-terminally located CysR and CTLD1 domains were highly sensitive and specific for the detection of domain-specific antibodies, as shown by the validation experiments using Western blot techniques. The CysR domain was recognized by 145 (97.3%) out of 149 MN patients, and the CysR-specific antibody level was highly correlated with the total PLA2R1-ab level (Spearmans rho = 0.949, p<0.001). In addition, CTLD1-ab were detected in 78 (52.3%) patients of the cohort. Again, a close correlation with the total PLA2R1-ab level was observed (Spearmans rho = 0.641, p<0.001). In contrast, the ELISA of the C-terminally located CTLD7 and CTLD8 domains exhibited a lower level of sensitivity compared to the Western blot technique. Precisely, all 149 MN patients of the cohort recognized the C-terminal CTLD7-8 domain in Western blot, while only 57 (38.2%) and 15 (10.1%) patients were tested positive in the CTLD7- and CTLD8-specific ELISA, respectively. A week correlation was observed between the CTLD7-ab level and the PLA2R1-ab level (Spearmans rho = 0.398, p=0.002). After adjustment for the total PLA2R1-ab levels, PLA2R1 domain-specific antibody levels could not predict the clinical outcome of patients in our cohort.

Conclusion

The total PLA2R1-ab levels, but not the PLA2R1 domain-specific antibody level, are predictive for the clinical outcome of patients with MN.

Funding

  • Government Support - Non-U.S.