Anti-phospholipase A2 receptor antibodies in membranous nephropathy and clinical correlation

Abstract

Circulating autoantibody to M-type phospholipase A2 receptor (PLA2R) is known as an important pathogenic antibody of idiopathic membranous nephropathy (MN) in adults. However, there has been a discrepancy on relationship between anti-PLA2R and clinical disease activity. Previous studies had several flaws including insufficient study subjects and different time-points and methods for anti-PLA2R measurement. In order to overcome the limitations, I measured anti-PLA2R with western blotting using serum samples obtained at the time of kidney biopsy from relatively large number of MN patients. Anti-PLA2Rs were detected in 69 (69.0%) idiopathic MN patients at initial diagnosis. However, the prevalence of the autoantibodies in patients who entered remission after treatment was lower (15.8%) compared with patients in an initial diagnostic phase. There was a significant correlation between anti-PLA2R reactivity and clinical disease activity. Proteinuria and hypoalbuminemia were more severe in patients with anti-PLA2R than those without the autoantibodies (2.95 g/g vs. 6.85 g/g, P=0.003, 3.1 g/dL vs. 2.5 g/dL, P=0.004). Furthermore, these clinical severities were increased proportionally as anti-PLA2R levels increased (P=0.015 and P for trend<0.001 for proteinuria and hypoalbuminemia, respectively). However, neither presence of anti-PLA2R nor anti-PLA2R levels showed a significant correlation with clinical outcomes including remission rate and time to remission. In conclusion, anti-PLA2R is pathognomonic for idiopathic MN in Korean ethnic group as well, and reflects a clinical disease activity. However, both the presence of anti-PLA2R and the levels of anti-PLA2R cannot predict the clinical outcomes in current clinical practice.