Immunohistochemical study of endothelin-1 (ET-1) in human acute renal allograft rejection.

Immunoperoxidase staining was carried out using monoclonal antibody against endothelin-1 on renal allograft biopsy specimens from thirty one patients with acute renal transplant rejection: Banff 97 score IA (n = 11), score IB (n = 10) and score IIA (n = 10). As a control 10 biopsy specimens of the kidneys removed because of trauma were used. Endothelin-1 immunostaining was investigated in the renal interstitial vasculature and tubular epithelium. In the normal kidney the immunoreactivity of endothelin-1 was demonstrated in vascular endothelial cells and tubular epithelial cells. The intensity of endothelin-1 staining in endothelial cells in renal allograft biopsies from patients with Banff score IA and IB was similar to controls. In biopsies with Banff score IIA a marked decrease in endothelin-1 immunostaining of endothelial cells was seen. Moreover, renal tubular epithelium from patients with acute allograft rejection with Banff score IB and IIA had elevated endothelin-1 immunoreactivity as compared with controls. The results showed altered endothelin-1 immunostaining in renal biopsy specimens in patients with acute transplant rejection. In acute tubulointerstitial rejection Banff IB and acute vascular rejection Banff IIA up-regulation of endothelin-1 on tubular epithelial cells was present, meanwhile in acute vascular rejection diminished immunoreactivity of endothelin-1 on endothelial cells was noted. In conclusion, our study suggests that endothelin-1 play an important role in renal tissue injury in acute tubulointerstitial and vascular allograft rejection.