Renal Phospholipase A2 Receptor in Hepatitis B Virus-Associated Membranous Nephropathy

Objective: This study examined the expression of renal phospholipase A2 receptor (PLA2R) in idiopathic and secondary membranous nephropathy (MN). Methods: Patients with biopsy-proven MN and non-MN were enrolled. Renal PLA2R was examined using an anti-PLA2R antibody (anti-PLA2R-Ab), and circulating PLA2R-Ab was detected by indirect immunofluorescence. Results: Renal PLA2R was detected along the capillary loop in 84% patients with idiopathic MN but not in those with any other primary glomerulonephritis. Only 1 of 38 patients with class V lupus nephritis showed renal PLA2R positive. In hepatitis B virus-associated MN (HBV-MN), 64% showed renal PLA2R positive, and PLA2R overlapped with HBsAg along the capillary loop. In addition, renal PLA2R positivity was closely associated with serum PLA2R-Ab. Renal PLA2R positive was present in all the patients with serum PLA2R-Ab positive and in 53% of patients with serum PLA2R-Ab negative. However, in patients with renal PLA2R negative, serum PLA2R-Ab was all negative. Conclusion: Renal biopsy PLA2R positivity was common in idiopathic MN and HBV-MN but rare in lupus-associated MN, and it was closely associated with serum PLA2R-Ab production. Further studies examining the association between PLA2R and HBV-MN may shed light on the mechanism of idiopathic MN or HBV-MN.