Distribution of donor-specific antibodies in the cortex and the medulla of renal transplants with chronic allograft nephropathy

Background: Emerging data suggest that donor-specific HLA antibodies should be more frequently found onto the transplant itself than in the bloodstream. It is now possible to detect such antibodies in kidney transplant needle biopsy samples by flow cytometry. In order to know if the detection of antibodies into such blind biopsy samples depends of the site of the biopsy, we have studied the distribution of antibodies in both the cortex and medulla of 12 transplants removed after graft loss due to chronic allograft nephropathy, and in 10 controls. Methods: Donor-specific HLA antibodies were extracted from the cortex and the medulla of each removed transplant by an acid elution and characterized by Luminex(R) assays. Results: They were found in 58.3% of transplants with chronic allograft nephropathy and never in other kidney samples. The same antibodies were found in the bloodstream at the time of transplantectomy in only 16.6% of the recipients. The distribution between the cortex and medulla was concordant in 75% of cases. However, we observed 2 discrepancies: one in favor of the cortex and one in favor of the medulla. A majority (5/7) transplants with CAN and intra-graft donor-specific antibodies had also Cod deposits along peritubular capillaries. Conclusion: Testing for donor-specific HLA antibodies in kidney transplant needle biopsies can be of value provided the biopsy includes both the cortex and the medulla. (C) 2007 Elsevier B.V. All rights reserved.