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Abstract: TH-PO1003

Optimization of the Cutoff Value for a Commercial Anti-PLA2R ELISA to Diagnose PLA2R-Associated Membranous Nephropathy in Japanese Patients

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Akiyama, Shin'ichi, Nagoya University Graduate School of Medicine, Nagoya, Japan
  • Hachiya, Asaka, Nagoya University, Nagoya, Japan
  • Maruyama, Shoichi, Nagoya University Graduate School of Medicine, Nagoya, Japan
Background

Anti-PLA2R antibodies (aPLA2R-Ab) is a potentially useful diagnostic and therapeutic biomarkers for PLA2R-associated primary membranous nephropathy (PLA2R-pMN). aPLA2R-Ab titer is easily quantified by a commercial ELISA kit. However, we observed more false-negative results in our experiments in Japan, when considering the manufacturer’s cutoff value (14 RU/ml) for ELISA than with western blot (WB) analysis and a commercial IIFT-CBA, indicating that the manufacture’s cutoff value is too high for the diagnosis of aPLA2R-Ab in Japanese PLA2R-pMN patients. Hence, it is important to optimize the cutoff value for ELISA in each region. This study aimed to investigate the optimal index cutoff value of the commercial aPLA2R-Ab ELISA kit for Japanese patients with PLA2R-pMN.

Methods

The aPLA2R-AB in serum samples from 117 patients with biopsy-proven primary membranous nephropathy (MN) were measured by WB and commercial ELISA (EUROIMMUN AG). WB analysis was performed under non-reducing condition and with diluted sera at x1/101. The ELISA was used in accordance with the manufacturer’s instructions. Primary MN patients were divided into an aPLA2R-Ab-positive group and a -negative group per the results of WB. Receiver operating characteristic (ROC) curves were plotted to generate the cutoff value for screening aPLA2R-Ab positive patients diagnosed via WB analysis from among all patients with pMN. Furthermore, to confirm the absence of changes in specificity, disease control sera from 30 each patients with secondary MN and other glomerulonephritis were measured by the ELISA.

Results

WB revealed that of 117 patients with pMN, 59 were aPLA2R-Ab-positive; 58, -negative. ROC curve analysis revealed a cutoff value of 5 RU/ml with a sensitivity and specificity of 50% and 93%, respectively. With a cutoff value of 5 RU/ml, none of the aPLA2R-Ab-positive serum samples were screened from disease control groups. The index cutoff value decreased from 14 to 5 RU/ml, thereby improving the sensitivity of the aPLA2R-Ab ELISA from 39% to 48%.

Conclusion

The optimal cutoff value of the aPLA2R-Ab ELISA for Japanese patients with PLA2R-pMN is 5 RU/ml. The cutoff value, thus optimized, of the ELISA enhanced the interpretation and confidence levels in the screening of PLA2R-pMN and eliminated the need for confirmation via WB analysis.

Funding

  • Government Support - Non-U.S.