Sirolimus-induced pneumonitis after renal transplantation: a single-center experience.

PURPOSE: Sirolimus is a potent immunosuppressive agent used with increasing frequency in kidney transplantation. However, sirolimus can increase the rate of unexplained interstitial pneumonitis. The aim of this study was to evaluate the clinical characteristics of sirolimus-induced pneumonitis and the therapeutic results in renal transplant recipients. PATIENTS AND METHODS: Seventy-two patients received sirolimus, conversion or de novo regimen, at our center between January 2007 and April 2011. Twelve of the 72 patients (16.7%) developed interstitial pneumonitis. The patients were divided into three groups according to the following indications of sirolimus use: de novo, early conversion, and late conversion groups.
RESULTS: The mean duration of follow-up was 11.0 ± 11.5 months. The mean blood level of sirolimus measured by microparticulate enzyme immunoassay was 16.5 ± 7.4 ng/mL at the time of diagnosis. The mean time from the start of sirolimus to pneumonitis onset was 14.7 ± 8.0 months. The clinical presentation included fever, cough, dyspnea, general weakness, and periorbital edema. In most cases, radiological imaging tests revealed bilateral lower-lobe involvement. Bronchoalveolar lavage was performed in three patients and two patients showed lymphocytic alveolitis. Sirolimus was discontinued or reduced for the treatment of pneumonitis. All cases of pneumonitis were resolved within 2 to 4 weeks.
CONCLUSION: Sirolimus blood level should be monitored tightly and early intervention is important when sirolimus-induced pneumonitis is suspected.