Ultrasensitive Quantitation of Anti-Phospholipase A2 Receptor Antibody as A Diagnostic and Prognostic Indicator of Idiopathic Membranous Nephropathy

Abstract

Anti-phospholipase A2 receptor antibody (PLA2R-Ab) is useful for affirming the diagnosis of idiopathic membranous nephropathy (IMN). Time-resolved fluoroimmunoassay (TRFIA) is highly sensitive and quantitative for measuring serum PLA2R-Ab immunoglobulin (IgG). We measured PLA2R-Ab levels with TRFIA in sera from 172 patients with IMN (n = 69), secondary MN (n = 9), and those with other glomerulonephritis (n = 94) at the time of renal biopsy compared to healthy controls (n = 286). Serum anti-PLA2R-IgG levels in healthy volunteers ranged from 0.09–0.91 mg/L. We set the cutoff value of the anti-PLA2R-IgG titer at 0.91 mg/L, with a sensitivity of 84.06% for diagnosing IMN. Increasing the cut-off value to 2.025 mg/L altered the sensitivity for diagnosing IMN to 71.01%, but with 100% specificity. IMN patients had significantly higher serum anti-PLA2R-IgG levels compared to those with secondary MN. PLA2R-Ab titers negatively correlated with estimated glomerular filtration rate (eGFR). Patinets with high titers had significantly lower serum albumin and eGFR, higher proteinuria and serum creatinine levels, accompanied by a lower complete remission rate. High titers of PLA2R-Ab were associated with poor prognosis of patients with IMN. TRFIA-based quantification of anti-PLA2R-IgG can be a reliable approach for the diagnosis and prognostication of patients with IMN.

Development of a Standardized Chemiluminescence Immunoassay for the Detection of Autoantibodies Against Human M-Type Phospholipase A2 Receptor in Primary Membranous Nephropathy

“…The anti-PLA2R-positive rates detected by ChLIA (83.9%), ELISA (73.5%), and RC-IFA (83.2%) were equal to or higher than the prevalence data determined among non-preselected patients with pMN by different methods, such as Western blot (53.0%-81.7%), 10,11 RC-IFA (48.0-82.3%), 12,13 ELISA (50.0-71.8%), 14,15 addressable laser bead immunoassay (51.5-66.9%), 16,17 luciferase immunoprecipitation systems assay (53.3%), 18 and time-resolved fluoroimmunoassay (71.0-89.7%). 19,20 These variations may be due to differences in assay techniques (e.g., epitope exposure, cutoff values, detected Ig subclass) and cohort characteristics (e.g., ethnicity, immunosuppressive treatment). Recently, Burbelo et al 18 reported a quantitative PLA2R-NanoLuc luciferase immunoprecipitation system assay that provides high diagnostic performance (receiver operating characteristics area under the curve ¼ 1.0) and is, just like the novel ChLIA, more sensitive in detecting anti-PLA2R seropositivity than the ELISA.…”

Primary Membranous Glomerulonephritis: The Role of Serum and Urine Biomarkers in Patient Management

“…This is a highly specific antigen-antibody binding reaction by measuring light-emission from labels conjugated from protein [71,72]. This assay has high sensitivity, used in the quantitative measurement of serum PLA 2 R-Ab immunoglobulin (IgG4) [73].…”

The clinicopathological features of patients with membranous nephropathy

“…31 In general, anti-PLA2R antibodies is considered as a useful biomarker for early diagnosis and prognosis in patients with MN. 32 In this study, we compared the baseline characteristics of MN patients according to their anti-PLA2R antibodies test results. The results demonstrated that MN cases who were positive for anti-PLA2R antibodies had significantly decreased TP, ALB, TB, DB, IgG; and upregulated CH, CK, LDL, D2.…”