Histological outcome of acute cellular rejection in kidney transplantationafter treatment with methylprednisolone

Background Several studies comparing the response of acute cellular rejecti on (ACR) episodes to different corticosteroid regimens have been conducted. However, in mast of them, the histological evaluation of the infiltrate an d its correlation with clinical response was not studied. The clinical and histological outcomes of 37 episodes of ACR treated with methylprednisolone (MP) were studied, with the aim to determine how long the infiltrate takes to be cleared after therapy. Methods. A total of 37 patients with biopsy-proven ACR were treated with 8 or 16 mg of MP/kg/day. Allograft biopsies were repeated at 5 and 10 days af ter the end of corticotherapy, Clinical and histological outcomes were comp ared. Results. Six patients were excluded; 15 (48.4%) patients responded to thera py; the mean serum creatinine of these patients reached normal levels in th e 2 weeks that followed treatment. Nine patients (60%) of this group had si gns of ACR on biopsies done 5 days after corticotherapy, and four (26.7%) m aintained them on the 10th day. Among 16 patients with no clinical response , none reached normal serum creatinine levels; 15 (93.7%) had signs of reje ction 5 days aft-er treatment and maintained them on the 10th day. Histolog ical signs of ACR disappeared in 73.3% of patients with clinical response 1 0 days after therapy, but in only 6.3% of patients with no response (P = 0. 001), Conclusions. Biopsies performed 5 days after treatment show a high incidenc e of features of ACR; such features take on average 10 days to disappear in nearly 75% of cases with successful therapy with MP.