Comparing transplant glomerulopathy in the absence of C4d deposition and donor-specific antibodies to chronic antibody-mediated rejection

Introduction: Transplant glomerulopathy (TG) is the characteristic lesion of chronic antibody-mediated rejection (AMR). However, in some patients presents with no circulating HLA antibodies or C4d positivity. Aim: Patients with TG accomplishing criteria for chronic AMR were compared to patients with isolated TG. Patients and Methods: We reviewed late (>6 months) graft biopsies performed between 2007 and 2010 (n = 75). Biopsies with C4d-negative TG and no circulating donor-specific antibody were called isolated TG (n = 12), and chronic AMR was defined according to Banff consensus (n = 17). HLA antibodies were evaluated by Luminex technology. Immunohistochemistry was performed to quantify graft infiltrating cells. Results: Patients with isolated TG were older (52 14 vs. 35 14; p = 0.0048), received grafts from older donors (54 16 vs. 41 18; p = 0.0554), and displayed a lower inflammation in the glomerular (g- score: 0.5 0.5 vs. 1.0 0.9; p = 0.0865; CD3 positive cells/glomeruli: 1.5 2.9 vs. 4.4 4.1; p = 0.0147), interstitial (i-score: 1.2 0.9 vs. 1.9 1.0; p = 0.0685; CD45 positive cells/hpf: 18 11 vs. 57 68; p = 0.0132), and peritubular capillary (ptc-score 0.2 0.6 vs. 1.1 0.9; p = 0.0089; CD45 positive cells/hpf: 3.7 3.1 vs. 10.1 7.4; p = 0.0290) compartments. Fifteen grafts were lost and graft survival was significantly lower in patients with chronic AMR (p = 0.0122). Conclusion: Isolated TG is associated with less severe allograft inflammation and with a better outcome than chronic AMR.