Protocol Biopsies in Kidney Transplant Recipients: Histologic Findings as Prognostic Markers for Graft Function and Outcome

The aim of the present study was to identify subclinical and borderline rejections as well as histological markers of chronic allograft nephropathy (CAN) among protocol biopsies performed at 1 and 6 months after living related kidney transplantation to assess their possible implications for graft function. Twenty paired allograft biopsies performed at 1 and 6 months were reviewed according to the Banff scoring scheme. The mean ages of donors and recipients were 59.6 ± 13.8 and 34.4 ± 8.7 years, respectively. Among all biopsies only 10% (4/40) showed no histopathological lesions. At the first month borderline rejection was shown in 35% and subclinical rejection in 10% of patients. At 6 months the proportion of findings was even higher, namely, 40% and 30%, respectively. When divided according to donor age, donors above 55 years showed a mean CAN score of 2.33 ± 1.56 which increased to 5.0 ± 2.26 on the 6 month biopsy (214.3%). Unexpectedly, the proportion of these changes in the younger donor group also increased by 173.3%, which might have been explained by the greater number of borderline and subclinical rejections in the younger donor group at the 1 month biopsy. In conclusion, 1 month biopsy may be valuable to determine borderline and subclinical rejection and to prognosticate the outcome of renal allograft function. Our findings suggest a greater susceptibility of histological deterioration among the older donor population. However, the presence of an untreated rejection in the younger donor pool leads to a rapid impairment of the graft function accelerating the process of chronic allograft nephropathy.