INTRODUCTION: The utility of protocol allograft biopsies (at prespecified intervals regardless of allograft function) remains unclear even in patients with elevated immunological risk such as flow crossmatch positive (XM+) recipients. We reviewed biopsy findings in our living positive crossmatch recipient cohort to identify whether protocol biopsies were useful.

METHODS/RESULTS: We performed 41 XM+ kidney transplants between 9/1/2004 and 11/30/2012. All patients received pre- and post-txp plasmapheresis (PP) with IVIG replacement (100 mg/kg), maintenance therapy with tacrolimus, and mycophenolate. Induction therapy varied with time but included either an IL-2 receptor antagonist or Thymoglobulin® with/without intra-operative rituximab. All patients received IV methylprednisolone with taper to prednisone 20 mg daily by post-operative day 4. Protocol biopsies were performed at 1, 2, 4, 13, 26 and 52 weeks; then annually. The cohort was 43.8 ± 12.1 years old, 67% female, and 60% had received a previous transplant. In our cohort, 86% of recipients experienced an acute rejection of which 34% had AMR, 43% had ACR and 22% had both. The median time to rejection was 10 days. On follow up, 22% experienced allograft failure and 10% died with functioning allografts.

Only in 2 of the 33 patients was the first rejection episodes detected on "for cause" biopsies. Of the 31 rejections diagnosed on protocol biopsy, 20 were within the first two weeks. Time to first rejection was significantly shorter when detected by protocol biopsies (32 ± 81 vs. 419 ± 504 days, p=0.001). The utility of protocol biopsies is in finding patients who would not have been biopsied otherwise; patients with rejection may have a changing or elevated creatinine as indication for a biopsy. Of the 31 rejections episodes detected on protocol biopsy, 11(36.7%) were in patients with both stable renal function and a creatinine <2 mg/dL.

CONCLUSION: In our living XM+, protocol biopsies were useful in detection of 36.7% of rejections prior to evidence of significant renal dysfunction. Since all the subclinical rejections detected were treated with further immunosuppression, protocol biopsies appear to be useful in guiding the management of high immunological risk recipients.

« Back to 2013 American Transplant Congress