Peritubular capillary changes and C4d deposits are associated with transplant glomerulopathy but not IgA nephropathy

We examined our renal transplant population for glomerular diseases demonstrated on biopsy between January 1993 and April 2002, focusing on transplant glomerulopathy (TGP). Of 1156 patients followed in our clinics during this period, glomerular disease was diagnosed in 132 cases (11.4%). Glomerulonephritis was diagnosed in 86 transplants (7.4%), with IgA nephropathy (IgAN) being the commonest diagnosis [32 cases (2.8%)]. Thirty-one cases (2.7%) of biopsy-proven TGP were analyzed for associated factors compared with 27 cases (2.3%) of recurrent IgAN. Transplant glomerulopathy was less frequent with mycophenolate mofetil (MMF) and/or tacrolimus, whereas recurrent IgAN showed no such tendency (P= 0.02). Peritubular capillary (PTC) C4d deposition was observed in six of 24 cases (25%) with TGP but none with recurrent IgAN (P= 0.02). Peritubular capillary basement membrane (BM) multilayering was significantly greater in TGP (4.92 +/- 2.94) than in recurrent IgAN (1.86 +/- 1.04) (P < 0.001). The graft survival of TGP was worse than recurrent IgAN (P= 0.05). The association of TGP with BM multilayering and C4d deposits in PTC suggests a generalized disorder of the graft microcirculation and its BM, owing to antibody-mediated rejection in at least some cases. Transplant glomerulopathy has a serious prognosis but is less frequent in patients on newer immunosuppression, unlike recurrent IgAN.