As compared with the early immunosuppressive drugs (azathioprine, steroids, antilymphocyte serum) some newer agents have the following specific advantages:

C. Tacrolimus (FK506) has properties similar to those of cyclosporine but is especially valuable for rescue of grafts that are failing on cyclosporine therapy.

DISCUSSION: Cyclosporine interferes with production of cytokines and lacks the bone marrow toxicity of azathioprine. Unfortunately its chief toxicity is renal. Although OKT3 is more available, more uniform, and more specific than antilymphocyte serum, some of its side effects are even greater, such as fever, chills, nausea, vomiting, diarrhea, and pulmonary edema. Tacrolimus has been used most extensively for liver grafts. It has been found especially valuable in reversing rejection of failing grafts.