Clinical and pathological assessment of acute vascular rejection in the transplant kidney

Acute vascular rejection (AVR) in kidney transplantation is the most important factor influencing graft prognosis. We focus on patients whose grafts were lost because of AVR, and assessed their clinical characteristics and histological findings of biopsied renal grafts. Biopsied specimens exhibited AVR in 43 patients who underwent kidney transplantation in the Kidney Center of Tokyo Women's Medical University from 1995 to 1999. In the follow-up from 1 to 5 yr (median: 2.5 yr) we classified these patients into three groups: favourable prognosis group (FPG), relatively poor prognosis group (RPPG) and poor prognosis group (PPG). Light microscopic study for histological grading of acute rejection according to the Banff scheme and detection of the C4d complement deposition on peritubular capillaries by the immunofluorescence method were performed. Based on the results, the donors of RPPG and PPG were significantly older than those of FPG, and all factors of acute rejection according to the Banff scheme were not statistically significantly different among the three groups. However, an acute tubular injury mimicking acute tubular necrosis (ATN) was observed in the biopsy specimens from PPG. In conclusion, an older donor is a risk factor of poor prognosis of the graft with AVR, and acute tubular injury mimicking ATN is one of the important features that enables the prediction of graft failure originating from AVR in kidney transplantation.