The evolution of untreated borderline and subclinical rejections at first month kidney allograft biopsy in comparison with histological changes at 6 months protocol biopsies.

Our study sought to identify the possible implications of histological findings of borderline and subclinical rejections as well as histological markers of chronic allograft nephropathy (CAN) in protocol biopsies at 1 and 6 months after living-related kidney transplantation. Twenty-eight paired allograft biopsies were blindly reviewed using Banff '97 criteria, among which only 10.7% (6/56) showed no histopathological lesions. BR was found in 9/28 (32.1%) and 6/28 (21.4%), and SR in 3/28 (10.7%) and 10/28 (35.7%) of the patients, in the 1 and 6 month biopsies, respectively. The mean CAN score (sum of histological markers for chronicity) increased significantly at 6 months biopsy, 1.57 +/- 1.36 vs. 4.36 +/- 2.32 (p < 0.01). When compared according to chronicity index (CI < 5 >), the high CI group had a mean CAN score of 2.36 +/- 1.15 at 1 month, which increased to 5.14 +/- 1.99 at 6 months biopsy (188.9%). The proportion of these changes in low CI group were also increased from 0.79 +/- 1.12 to 3.57 +/- 2.38 (451.9%). In conclusion, a protocol 1 month biopsy may uncover a high prevalence of BR or SR in stable allografts. The presence of an untreated BR or SR in biopsies with low chronicity index showed greater susceptibility to histological deterioration on the 6 month biopsy, associated with rapid impairment of graft function and chronic allograft nephropathy.