Comparison of 2 Anti-PLA2R Immunoassays for the Diagnosis of Primary Membranous Nephropathy

Background: Anti-phospholipase A2 receptor (anti-PLA(2)R) is a promising biomarker for diagnosis, activity evaluation, therapy monitoring, and prognostic estimation of primary membranous neuropathy (pMN). Difference in methodology may be one cause of the discrepancy in anti-PLA(2)R-positive percentages in reported studies. In this study, we evaluated the determination consistency of anti-PLA(2)R using indirect immunofluorescence assay (IIF) and enzyme-linked immunosorbent assay (ELISA). Methods: A total of 113 patients with pMN, 34 with secondary membranous neuropathy (sMN), and 53 healthy control individuals were enrolled. We tested their circulating anti-PLA(2)R, along with other biochemical parameters, using IIF and ELISA. Results: The sensitivity of anti-PLA(2)R for pMN was 70.8% by IIF and 67.3% by ELISA, with no statistically significant difference. The overall qualitative agreement of anti-PLA(2)R was 91.15% (95% confidence interval [Cl], 85.91%-96.39%), and the correlation coefficient was 0.79 for IIF versus ELISA. The overall correlation coefficient of anti-PLA(2)R titers by IIF and concentration by ELISA was 0.85. Through ROC analysis, anti-PLA(2)R as measured by IIF and ELISA showed larger areas under the curve (AUCs) than other biochemical parameters. Conclusion: ELISA shows similar performance to IIF, with the advantages of quantitative results and suitability for high throughput.