The effect of conversion from cyclosporin to azathioprine on renin-containing cells in renal allograft biopsies.

Renal biopsies were examined from 17 renal transplant recipients before and after conversion from cyclosporin to azathioprine, and in 17 patients who remained on cyclosporin. All patients had stable renal function. We used an immunoperoxidase technique with an antiserum to human renin to identify renin-containing cells. We demonstrated hyperplasia of renin-containing cells in patients treated with cyclosporin. Numbers of renin-containing cells decreased after conversion to azathioprine. We suggest that local activation of the intrarenal renin-angiotensin system could mediate the effects of cyclosporin on renal haemodynamics. This could play a role in the pathogenesis of cyclosporin nephrotoxicity and cyclosporin hypertension.