Fine-needle aspiration cytology monitoring of elective conversion from cyclosporin to azathioprine and prednisolone.

The elective conversion of renal allograft recipients from cyclosporin (CsA) to azathioprine and prednisolone has the advantage that the long-term risk of CsA nephrotoxicity is reduced, but it may precipitate a rejection episode. We have monitored this period by fine-needle aspiration cytology (FNAC) in 24 patients undergoing conversion of immunosuppression 6 months after transplantation. As expected the serum creatinine and alkaline phosphatase were significantly reduced and the mean creatinine clearance was significantly increased after conversion. FNAC exhibited increased mononuclear cellular infiltration in 13 of the 24 patients. In nine patients there was a transient infiltration of lymphocytes and monocytes without changes in the normal parameters of renal function. In four others 'blast' cell infiltration was evident in association with rejection episodes. All four responded to pulsed doses of methylprednisolone. However, two other patients had late rejection episodes (2 and 6 months after conversion) which were steroid resistant and required reintroduction of CsA. No grafts were lost (median follow-up 9 months). This study has shown that although overt rejection occurred in only 16.6% of patients, cellular infiltration was present in over 50% during conversion of immunosuppression. FNAC failed to identify clearly the patients at risk of rejection during conversion of therapy.