IMMUNOPATHOLOGICAL PATTERNS IN LONG-TERM RENAL ALLOGRAFTS

Abstract

Forty-eight consecutive core needle biopsies obtained 12-158 months after transplantation from 48 human renal allografts were analyzed. A conventional histological investigation and an immunohistochemical analysis of various markers of the immune system were performed, as well as cytological analyses of simultaneously obtained fine-needle aspiration biopsies. Findings were compared in grafts with excellent or reduced function and in patients who were immunosuppressed with azathioprine or cyclosporine. All the patients with excellent renal graft function (serum creatinine level less than or equal to 120 mumol/L) showed a normal picture with respect to both FNAB pattern and immunohistology, irrespective of the type of immunosuppression. Thus, the presence of inflammatory cell infiltration in a long-term renal graft suggests a pathological process of potential clinical significance. Biopsies from CsA-treated patients with reduced renal graft function (serum creatinine greater than 120 mumol/L) showing either a normal picture or focal interstitial fibrosis on histological examination were also usually normal with respect to both FNAB cytology and the immunohistological pattern. Five of 36 biopsies with reduced function showed an immunohistochemical pattern with signs of immune activation indistinguishable from those seen in early acute rejection. In cases with histological signs of chronic rejection, the immunopathological pattern varied, which suggests that different pathogenetic mechanisms were involved.