Prolonged limb allograft survival with short-term treatment with FK-506 in rats.

The effect of the new immunosuppressive agent FK-506 on rat limb allograft was investigated across the BN-to-F344 histocompatibility barrier. A 14-day course of FK-treatment at doses of 1 mg/kg per day or more, begun on the day of operation, significantly increased the period of graft survival. Additional studies demonstrated that single treatment with FK only on the day of operation prolonged the graft survival in a dose-dependent manner. These results stress the profound immunosuppressive effect of FK and suggest the possible future application of composite tissue allograft in humans.