Clinicopathological analysis of transplant glomerulopathy cases

Transplant glomerulopathy (TG) is involved in the criteria of chronic active antibody-mediated rejection (c-AMR) in Banff 07 classification. In this report, we discuss the clinico-pathological analysis of TG cases after renal transplantation, and analysis of whether all TG cases are applied to c-AMR.

Transplant glomerulopathy, defined by double contours of glomerular basement membranes, was diagnosed in 13 patients from 13 renal transplant patients followed-up in our institute between January 2007 and April 2008. We retrospectively reviewed these 13 patients.

Among 13 cases of TG, three cases were mild (cg1 in Banff classification), four were moderate (cg2), and six were severe (cg3). Transplant glomerulitis and interstitial inflammation were present in all 13 biopsies, and peritubular capillaritis was present in 12 of 13 biopsies, interstitial fibrosis/tubular atrophy in 13, and the thickening of the peritubular capillary (PTC) basement membrane in 11. PTC C4d deposition was presented in six cases, three out of six cases had diffuse C4d deposits in PTC, and the remainder had focal deposits. By assaying with plastic beads coated with human leukocyte antigen (HLA) in 12 cases, the circulating anti-HLA alloantibody was detected in all 12 patients of which only 3 of 12 were donor-specific antibodies (DSA). In our cases, there was no patient who fully met criteria for c-AMR in Banff classification, which included TG, C4d deposition in PTC, and existence of DSA, but seven patients were diagnosed suspicious for c-AMR. Seven cases (54%) had proteinuria at the time of the biopsies and the severity of proteinuria was associated with the severity of TG. Deterioration of renal allografts' function after biopsies was seen in seven (54%), and two of them lost their graft.

We suggest that histopathological changes of TG accompanied by transplant glomerulitis, peritubular capillaritis, the thickening of the peritubular capillaries basement membrane, and circulating anti-HLA antibodies may indicate c-AMR, even if C4d deposition in PTC is negative. The severity of TG may be associated with proteinuria, reduced graft function, and reduced graft survival.