Usefulness of follow-up biopsies at one year after ABO-incompatible kidney transplantation.

Background: Due to the shortage of deceased donor kidneys, we have expanded the indications for living-donor kidney transplantation (LKT) including ABO-incompatible (ABO-i) donors in Japan. In this study, the utility of protocol biopsies was discussed in ABO-i LKT.
Methods: Protocol biopsies have been performed on kidney graft 1 hour, 3 weeks, and 1 year after LKT in our institution. The relationship between biopsies and clinical courses was considered retrospectively in 38 cases of ABO-i LKT. The immunosuppressive regimen consisted of anti-CD20 antibody, mycophenolate mofetil, prednisolone, calcineurin inhibitor (cyclosporine or tacrolimus), and anti-CD25 antibody. Anti-ABO blood type antibody removal by plasmapheresis was performed before LKT up to 32 times. The post-transplantation regimen consisted of mycophenolate mofetil or mizoribine as an antimetabolite.
Results: Episode biopsies have been performed in 6 cases within 3 weeks post-transplantation. Each pathological diagnosis was as follows: antibody-mediated rejection (AMR; 5 cases) and calcineurin inhibitor (CNI) nephrotoxicity (1 case). Subclinical chronic active AMR was found at 1 year post-transplantation follow-up biopsies in 4 of the 6 cases. Episode biopsies have been done in the other 6 cases from 1 month to 1 year post-transplantation. Each pathological diagnosis was as follows: acute T-cell-mediated rejection (TMR; 1 case), vesicoureteral reflux (VUR; 3 cases), CNI nephrotoxicity (2 cases), and VUR + CNI nephrotoxicity (1 case). AMR was also not found at 1 year post-transplantation follow-up biopsies in them. In all cases episode biopsies were performed based on pathological diagnosis and had no graft dysfunction after that.
Conclusions: Pathological study revealed that acute AMR was found early (ie, within 3 weeks) following transplantation. Although appropriate treatment made AMR go into remission once, chronic active AMR was often found at 1-year follow-up biopsies.
(Copyright © 2014 Elsevier Inc. All rights reserved.)