Clinical and pathological analyses of chronic vascular rejection after kidney transplantation.

AIM: We discuss the clinicopathological analysis of cases of chronic vascular rejection (CVR) cases after renal transplantation and clarify the mechanisms underlying the development and prognostic significance of CVR.

PATIENTS: CVR was diagnosed in 46 renal allograft biopsy specimens (BS) obtained from 34 renal transplant patients being followed up at the Department of Urology, Tokyo Women's Medical University, between January 2009 and December 2013.

RESULTS: CVR was diagnosed at a median of 47.4 months post-transplant. Among the 36 patients, 23 had a history of acute rejection. Among the 46 BS showing evidence of CVR, the CVR was mild (cv1 in Banff's classification) in 23, moderate (cv2) in 17, and severe (cv3) in 6. Of the 40 samples obtained at the time of the biopsy and assayed with plastic beads coated with HLA antigen, 31 (78%) showed circulating ant-HLA alloantibody, and 15 (38%) showed donor-specific antibodies. We then classified the 46 BS showing evidence of CVR by their overall histopathological features, as follows; cv alone was seen in 16 (35%) BS, cv + antibody-mediated rejection (AMR) in 26 (56%), and cv + T-cell-mediated rejection in 9 (19%). Loss of the renal allograft occurred during the observation period in nine of the patients (26%). Of the remaining patients with functioning grafts, deterioration of the renal allograft function after the biopsies occurred in 11 patients (32%).

CONCLUSION: The results of our study suggest that AMR may underlie CVR in many cases, while T cell-mediated rejection may play an important role in some cases.