Ultrastructural renal findings in allografted kidneys of patients treated with ciclosporin A.

22 renal biopsies of 22 patients with 6-month-old transplants have been examined at the light- and electron-microscopic level to demonstrate the toxic effects induced by ciclosporin A (CS). These patients presented stable renal function and were exempt from acute rejection symptoms or nephrotoxicity. Interstitial fibrosis, tubular atrophy and interstitial lymphocytic infiltration were the lesions most often observed by light microscopy. In a single case an arteriolar lesion suggestive of arteriolopathy due to Cs was seen. Ultrastructural observations of renal tubular cells showed a tendency of rough and smooth endoplasmic reticulum to microdilate and microvacuolize. In 4 out of 22 cases there were mitochondrial alterations with giant mitochondria. In only 1 case, clusters of cilia were seen. Clinical histological correlations show that interstitial fibrosis is directly proportional to CS blood level. CS higher blood levels suggest a higher risk of nephrotoxicity.