*Purpose: Membranous nephropathy (MN) in transplanted kidney is categorized as de novo or recurrent disease. This immune complex glomerulopathy presents with varying levels of proteinuria, and antibodies against phospholipase A2 receptor (PLA2R) have been detected. The long-term outcomes of renal allografts with MN have not been well-defined. Previous studies suggest that post-transplant MN may be associated with alloimmune response. We examined the natural progression of all renal transplants at our center with biopsy-proven MN to identify risk factors for developing this disease and to explore a possible link with acute antibody mediated rejection (AMR).

*Methods: We retrospectively analyzed renal transplant biopsies with MN done at our center from 2014 to 2020. Patients with systemic lupus erythematosus (SLE) were excluded from this study. Data including age, sex, race, type of transplant, etiology of ESRD, cPRA, induction agent, maintenance regimen, serum creatinine, eGFR, urine protein-to-creatinine ratio, DSA, and biopsy results were collected. If a patient had more than 1 biopsy, the patient was added to the PLA2R positive or AMR group if at least 1 biopsy suggested PLA2R positivity or acute AMR.

*Results: 52 biopsies with post-transplant MN from 31 patients were included in this study. AMR was observed in 33% of the patients with de novo disease (n=15), 45% in recurrent disease (n=11), and 50% in patients with unknown cause of initial ESRD (n=4) (Table 1). PLA2R stains were positive in 40% of patients with de novo disease, 82% of recurrent group, and 60% of patients with unknown cause of ESRD. 44% of the patients with PLA2R positivity had concomitant acute AMR (n=18), while 31% of the PLA2R negative patients had AMR (n=13).

*Conclusions: PLA2R positivity was statistically higher in recurrent disease than in de novo disease (p=0.018) suggesting more frequent secondary MN in the de novo group. Although not statistically significant, a trend for more frequent AMR was observed in the recurrent group (p=0.084). However, PLA2R status did not show a correlation with AMR. In addition, our results do not provide support for the hypothesized link between de novo MN and AMR.

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