The science of transplantation, now half of a century old, has dramatically increased and improved the life of many individuals, including many children, with end stage diseases. Recent advancements in immunosuppressive agents have substantially decreased rejection of allografts over the past decade and a half in the United States. Hariharan et al., N Engl J Med 342, 605-612 (2000); and First, M. R., Transplant Proc 34:1369-1371 (2002). However, to avoid both episodes of acute rejection and the initiation of chronic rejection following transplantation, immunosuppressive drugs must be administered over the entire life of the organ recipient. Consequences of this long-term administration are profound, including undesirable side effects, increasing the risk of infection, autoimmunity, heart disease, diabetes, and cancer. The chronic administration of these immunosuppressive drugs (especially when give systemically) lead to toxicity and significant side effects, thereby leaving the patient vulnerable to a variety of diseases and systemic organ failure.
The most desirable alternative to this extended state of vulnerability would be to render the patient's immune system to effectively suppress immune activation without systemic immunosuppression. In this case, no further immunosuppressant drug treatment would be necessary. Furthermore, the recipient's immune system would otherwise function normally, being capable of combating pathogens and malignant tumor cells. What is needed in the art are compositions and methods to induce permanent immunological tolerance by stimulating immunosuppressive regulatory cells.