Antibody-Mediated Rejection After Alemtuzumab Induction: Incidence, Risk Factors, and Predictors of Poor Outcome

Background. Antibody-mediated rejection (AMR) is associated with allograft loss. Identification of factors associated with poor outcome has not been extensively studied. Methods. We retrospectively studied 469 patients who received a negative crossmatch renal transplant with alemtuzumab induction. Forty-eight of 469 (10.2%) patients were treated for AMR. Thirty of 48 (62.5%) of the cases fulfilled the Banff criteria for definite AMR, whereas 18 of 48 (37.5%) were categorized as suspicious for AMR(tissue injury with C4d staining or donor-specific antibodies [DSAbs]). Sensitization, high human leukocyte antigen, and -DR mismatch were risk factors for the development of AMR (P=0.0016, 0.001, and 0.012, respectively). Results. Allograft survival was inferior in the AMR group (70.2%) compared with the nonrejector group (97.0%) (P<0.001). Forty-two of 48 (87.5%) of patients with acute AMR had DSAbs. Patients with CII DSAbs at the time of AMR, whether alone or in combination with CI DSAbs had the worst allograft survival (P=0.014). Both the mean cumulative and immunodominant mean fluorescence index were higher in those patients who subsequently lost their grafts (P<0.001). Patients with diffuse C4d staining had inferior allograft survival than those with focal C4d or no staining (P=0.02). There was no significant difference in survival by histological grade but a trend to inferior outcomes in those with vascular involvement (P=0.06). Those patients who met the full Banff criteria had worse survival than those with suspicion for AMR only (P=0.04). Conclusion. This study identifies patients at risk of graft failure from AMR. These patients may benefit from newer therapeutic strategies including the use of eculizumab or bortezomib.