Some of the immune system's biggest battles are directed not against harmful intruders but against potentially life-saving organ transplants. New hearts and kidneys in adults have become fairly commonplace, and top surgeons have even attempted the daunting feat of transplanting multiple abdominal organs into infants and toddlers. Today's organ recipients are indebted to a drug called cyclosporine, which has revolutionized transplantation technology in the past decade. Unlike immunological treatments for AIDS and cancer, cyclosporine works by temporarily suppressing the body's natural defenses, thus preventing the rejection of grafted tissue.
The miracle of cyclosporine comes at a steep price. The drug can...
