Abstract:

Objective To investigate the performance of 4 methods [enzyme-linked immunosorbent assay （ELISA），indirect immunofluorescence assay（IFA），flow luminescence immunoassay（FLIA）and chemiluminescence immunoassay（CLIA）] in determining anti-phospholipase A2 receptor（PLA2R）antibodies in the diagnosis of primary membranous nephropathy（PMN）. Methods A total of 103 patients with PMN（PMN group），177 patients without PMN（non-PMN group）and 40 healthy subjects（healthy control group）were enrolled from Shanghai General Hospital from September 2023 to June 2024. The clinical data were collected，and serum anti-PLA2R antibodies were determined using the 4 methods. The optimal cut-off value for determining anti-PLA2R antibodies in diagnosing PMN was obtained using receiver operating characteristic（ROC）curve，and the cut-off value was verified using the serum samples of healthy control group. Results The sensitivities of IFA，CLIA，FLIA and ELISA for determining serum anti-PLA2R antibodies were 84.47%，82.52%，78.64% and 63.11%，respectively. The specificities were 100%. The areas under curves（AUC）for determining serum anti-PLA2R antibodies in diagnosing PMN by ELISA，FLIA and CLIA were 0.988 2，0.988 7 and 0.970 7，respectively. The cut-off values were set at 2.730 RU·mL^-1， 7.015 U·mL^-1 and 3.705 U·mL^-1，respectively，which could improve the sensitivity without significantly reducing the specificity. The cut-off value of IFA was 1∶10，and its diagnostic efficacy for PMN was the highest. Conclusions Among the 4 methods，IFA has the highest sensitivity，followed by CLIA and FLIA，and ELISA has the lowest. When the cut-off values of ELISA，FLIA and CLIA are set at 2.730 RU·mL^-1，7.015 U·mL^-1 and 3.705 U·mL^-1，respectively，the diagnostic sensitivity of PMN could be improved without significantly reducing specificity.

Key words: Anti-phospholipase A2 receptor antibody, Indirect immunofluorescence assay, Flow luminescence immunoassay, Chemiluminescence immunoassay, Primary membranous nephropathy