Anti-PLA(2)R Antibodies in Chinese Patients with Membranous Nephropathy

BACKGROUND: This study used 2 standardized methods to evaluate anti-PLA(2)R antibody in sera of Chinese patients with primary membranous nephropathy (PMN) and to determine whether immunological reactivity reflected by antibody titer correlates with kidney function parameters. MATERIAL/METHODS: Overall, 82 subjects with biopsy-proven primary membranous nephropathy (PMN), 22 cases with secondary membranous nephropathy (SMN), 40 non-MN patients with established glomerulonephritis, and 20 healthy volunteers were recruited from the Division of Nephrology, Nanfang Hospital, China. Anti-PLA(2)R antibody in the serum of each patient was evaluated by both recombinant cell-based indirect immunofluorescence assay (RC-IFA) and enzyme-linked immunosorbent assay (ELISA). Kidney function was assessed by proteinuria for 24 hours, serum albumin, blood urea nitrogen (BUN), serum creatine, and serum cystatin C. We assessed the correlation between anti-PLA(2)R antibody levels and clinical parameters in the PMN patients. RESULTS: Fifty-three patients with PMN (64.6%) were positive for anti-PLA(2)R antibody. The level of antibody determined by RC-IFA ranged from 1: 10 to 1: 1000 and 0 to 1423 RU/ml by ELISA. The 2 anti-PLA(2)R test systems correlated very well with each other and reached an agreement of 95.7% for PMN patients. The level of antibody detected by ELISA in patients with PMN was also significantly correlated with proteinuria and nephritic-range proteinuria (>3.5 g/day). CONCLUSIONS: Anti-PLA(2)R antibody is sensitive and extremely specific for diagnosis of Chinese patients with primary membranous nephropathy. Concentration of autoantibody against PLA(2)R may be an ideal marker for monitoring the activity of immunological disease.