Early Versus Late Acute Antibody-Mediated Rejection in Renal Transplant Recipients

Background. Over the last decade, the diagnostic precision for acute antibody-mediated rejection (aABMR) in kidney transplant recipients has improved significantly. The phenotypes of early and late aABMR may differ. We assessed the characteristics and outcomes of early versus late aABMR. Methods. Between January 1, 2005 and December 31, 2010, aABMR was diagnosed in 67 grafts in 65 kidney recipients, with a median follow-up of 3.6 years (range, 61 days-7.3 years). Recipients were stratified by early aABMR (<3 months after transplantation; n=40) and late aABMR (93 months after transplantation; n=27). The main outcome was kidney allograft loss. Outcome of aABMR was compared with recipients with acute early (n=276) or late (n=100) non-ABMR during the same period. Results. Recipients with late aABMR had significantly reduced graft survival compared with recipients with early aABMR (P<0.001, log-rank test; 40% vs. 75% at 4 years; hazard ratio, 3.72; 95% confidence interval, 1.65-8.42). Graft survival in late aABMR was also inferior to late non-ABMR acute rejections (P=0.008). At transplantation, more patients were presensitized to human leukocyte antigens (22 [55%] vs. 4 [15%] in the early vs. late aABMR group). The late aABMR group was characterized by younger recipient age (37.9+/-12.9 vs. 50.9+/-11.6 years; P<0.001), increased occurrence of de novo donor-specific antibodies (52% vs. 13%; P=0.001), and nonadherence/suboptimal immuno-suppression (56% vs. 0%; P<0.001). Conclusion. Compared with early aABMR, late aABMR had inferior graft survival and was characterized by young age, frequent nonadherence, or suboptimal immunosuppression and de novo donor-specific antibodies.