De Novo Membranous Nephropathy Associated With Antibody-Mediated Rejection in Kidney Transplant Recipients.

Background: Membranous nephropathy (MN) is a rare autoimmune disease that can develop a persistent nephrotic syndrome and end-stage kidney disease, with a recurrence rate of 30% to 40% after kidney transplant.

Methods: Retrospective case series of membranous nephropathy observed in a cohort of kidney transplant recipients with donor-specific anti-human leukocyte antigen antibodies and biopsy-proven antibody-mediated rejection (AMR).

Results: We report 4 cases of membranous nephropathy associated with AMR. MN was diagnosed 10 to 92 months posttransplant, associated with de novo donor-specific antibodies, specific to class I in 2 cases, and class II in another 2. All cases presented typical morphology of membranous nephropathy, with subepithelial deposits with spikes at electron microscopy. Immunostaining for immunoglobulin G4 was negative in all cases, and podocyte-expressed M-type phospholipase A2 receptor was detected in glomerular basement membrane of 3 cases. Biopsy specimens from patients with longer follow-up showed more intense microvascular inflammation and chronic injury markers, possibly because of subclinical immunologic injury. AMR therapy included immunoglobulin 2g/kg in 3 patients, isolated or associated with plasmapheresis. One patient was not treated because of an active disseminated infection. Two patients remain with functioning grafts and under antiproteinuric therapy. Two grafts were lost, 1 because of chronic failure and the other because of death secondary to infection. Despite treatment, donor-specific antibodies remain detectable in a 6-month follow-up.

Conclusions: De novo MN is a rare manifestation associated with AMR in kidney transplant recipients. The occurrence of podocyte-expressed M-type phospholipase A2 receptor in de novo MN suggests antibody-mediated activation, despite the use of maintenance immunosuppression.