Anti-phospholipase A2 Receptor Antibody in Differentiation and Prognostication of Membranous Nephropathy

Anti-M-type phospholipase A₂ receptor (anti-PLA₂R) antibody is believed to be associated with primary membranous nephropathy (pMN) and absent in secondary MN (sMN). There are few data regarding utility of anti-PLA₂R antibody as a prognosticator. Our study aimed to compare the incidence of positive serum anti-PLA₂R antibody titer in pMN versus sMN and correlation with clinical outcome. From August 2015 to July 2019, patients with biopsy-proven MN were evaluated for serum anti-PLA₂R antibody titers by the enzyme-linked immunosorbent assay. The subset of cases was repeated to monitor the clinical response in terms of 24 h proteinuria. A total of 169 patients, 65 pMN and 104 sMN were studied. Anti-PLA₂R antibody was found in 41 (63.08%) pMN with mean titer, 232.62 RU/mL, and 40 (38.46%) sMN with mean titer 253.59 RU/mL. Out of positive antiPLA₂R antibody titer in pMN cases, 15 were retested twice to 5 times with mean titers of 78.95, 36.27, 13.9, and 15.45 RU/mL, respectively. Out of positive anti-PLA₂R antibody in sMN cases, 11 were retested twice to five times with mean titers of 104.42, 122.49, 12.33, and 17.2 RU/mL, respectively. All patients with decreasing anti-PLA₂R antibody titer in both groups had clinical remission, with a decrease in mean 24 h proteinuria from 7.11 g to 3.36 g in pMN and 5.97 g to 3.41 g in sMN. Ten pMN and 11 sMN patients without remission showed persistent positive anti- PLA₂R antibody titer. Anti-PLA₂R antibody titer may be elevated in pMN/sMN. It can also be used as a noninvasive prognostic marker for MN.