Effects of cyclosporin, FK506, and rapamycin on graft-vessel disease.

Graft-vessel disease (GVD) limits the long-term survival of heart-transplant patients, and this effect has not been altered by use of cyclosporin for immunosuppression. We compared the effects of the immunosuppressants cyclosporin, FK506, and rapamycin on GVD in a rat-heart transplantation model. Allografted hearts from rats treated with 1 mg/kg FK506 for 50 days showed the same degree of myocardial rejection but a significantly worse (p less than 0.05) grade of GVD compared with grafted hearts from rats treated with 1.5 mg/kg cyclosporin for the same time. 2 mg/kg FK506 for 50 days prevented cellular rejection but GVD was as severe as that found with 1 mg/kg FK506. Moderate GVD was present in two of five allografted hearts after treatment with 4 mg/kg FK506. 1.5 mg/kg rapamycin for 50 days was an effective inhibitor of rejection and GVD. Based on our results in rats, the possibility that GVD may occur in human heart-transplant recipients treated with FK506 cannot be excluded.