To the Editor: Proteinuria may develop in renal-transplant recipients who have converted from treatment with calcineurin inhibitors to treatment with sirolimus¹; the mechanism of this occurrence is unknown. We hypothesized that the antiangiogenic properties of sirolimus might be responsible. We determined the plasma concentrations and renal expression of vascular endothelial growth factor (VEGF) in a specimen from a renal-allograft biopsy performed to evaluate post-transplantation proteinuria during sirolimus conversion in a patient with Kaposi's syndrome.

A 68-year-old man with alcoholic cirrhosis and end-stage renal disease due to IgA nephropathy underwent cadaveric liver and renal transplantation in May 1996. Eight years . . .