Selected topics on FK 506, with special references to rescue of extrahepatic whole organ grafts, transplantation of "forbidden organs," side effects, mechanisms, and practical pharmacokinetics.

FK 506 is a superior immunosuppressive agent that should improve the grafting of organs that already are part of our every day transplant practices, as well as those which are presently impractical. Immune intervention for serious autoimmune diseases also should be a more attractive option with this drug. Lessons are still being learned about dosage and what determines safe dose schedules. At a basic level, the study of FK 506 and its comparison to CyA may have shed light on mechanisms and characteristics of the whole class of so-called macrolide immunosuppresants and their cytosolic binding sites.