Is cyclosporine's nephrotoxicity related to its immunosuppressive effectiveness?

A fatal early acute rejection occurred in a heart allograft recipient immunosuppressed with Cyclosporine. This failure to prevent rejection in spite of satisfactory plasma levels of Cyclosporine was associated with total absence of renal impairment. The latter has always been present in our experience. The absence of immune and nephrotoxic effects raises the question of a biological defect in this patient, possibly a lack of specific receptors for Cyclosporine.