Cyclosporine is a member of a family of drugs that possess immunosuppressive activity. These chemicals are very useful in helping the body to overcome it's natural tendency to reject transplanted organs. The term transplant was first used by John Hunter in 1778 when describing his experiments with ovarian and testicular grafts between unrelated animals. Transplantation had a rather rough beginning that was laced with failures until the first part of this century when Carrel and Guthrie pioneered reliable methods for joining blood vessels. The first recorded kidney transplant in man was carried out in 1933 by a Russian surgeon (Voronoy). It is unlikely that the kidney ever functioned as it had been harvested some 6 hours after the donor's death and the recipient died within 48 hours. Since then, organ, bone, and tissue transplants have become commonplace. Successful transplantation often requires the assistance of immunosuppressive agents that act to decrease the chances of immune rejection of the donated organ. The photomicrograph above illustrates crystallites of the immunosuppressive drug Cyclosporine. This drug is a natural metabolite of a soil fungus and is isolated from culture broths. It is currently one of the most useful drugs of its type.