Histological and Extended Clinical Outcomes After ABO-Incompatible Renal Transplantation Without Splenectomy or Rituximab

Background. Excellent shod-term results have been reported in ABO-incompatible (ABO) renal transplant recipients managed solely with antibody removal and conventional immunosuppression. However, long-term clinical outcomes with this regimen and predictive information from protocol biopsies are lacking. Methods. We compared outcome data in ABOi and ABC-compatible (AB0c) recipients receiving this regimen approximately 4 years posttransplant, and histology from biopsies approximately 12 months posttransplant. Results. Patient and graft survivals among 54 ABOi recipients were 98.1% and 90.7%, respectively, at 4 years. Graft function was similar between ABOi (creatinine, 140.3 mu mol/L) and ABOc recipients (creatinine, 140.2 mu moVL) (P = 0.99), with no significant change over the study period in either group (Delta creatinine, 0.83 vs 6.6 mu mol/L) (P = 0.59). There was no transplant glomerulopathy in biopsies from either group. Interstitial fibrosis (IF) and tubular atrophy (TA) was present in 7 (28%) of 25 ABCi compared with 7 (20.6%) of 34 ABOc (P = 0.52). Progression of IF/TA from implantation was noted in 6 (24%) of 25 ABOi and 6 (17.6%) of 34 ABCc, respectively. C4d staining without antibody-mediated rejection was present in 13 (52%) 25 early posttransplant biopsies from ABOi recipients by immunohistochemistry, but in only 4 (16%) of 25 at 12 months. Conclusions. ABC-incompatible renal transplant performed with antibody removal and conventional immunosuppression continues to provide excellent patient and graft survival, and stable renal function over 4 years. Coupled with absent transplant glomerulopathy and low rates of progressive IF/TA on earlier biopsies, this suggests that ABCi with conventional immunosuppression and antibody removal, without rituximab or splenectomy, can achieve long-term outcomes comparable to ABC-compatible transplantation.