Cyclosporin-A deposits in renal allografts.

Deposits of cyclosporin A (CyA), demonstrable by fine-needle aspiration biopsy and indirect immunofluorescence, are invariably seen in the transplant parenchymal cells in cases of CyA nephrotoxicity. Deposition of CyA is accompanied by concomitant changes in parenchymal-cell morphology but not by any significant inflammation. The degree of clinical nephrotoxicity is directly correlated with the amount of CyA in the graft but has no correlation with the dose of the drug and only a marginal correlation with the concentration of CyA in the recipient plasma. After reduction of dose, the deposits rapidly disappear from the transplant, with concomitant improvement of transplant function. It is concluded that demonstration of CyA in cytological specimens of a renal transplant is at present the best method of assessing CyA nephrotoxicity and of distinguishing nephrotoxicity from rejection.