Each year more than 19,000 transplants are performed in the United States. An additional 56,000 critically ill people in this country are waiting to receive an organ transplant that could forestall further disability or death from conditions such as heart disease, kidney failure, liver disease, and diabetes. Although advances derived from transplantation research have improved rates of transplant success and patient survival, problems such as complications from immunosuppressive therapy remain to be solved. Since the first successful organ transplant was performed in the United States in 1954, one of the most serious problems facing transplant patients has been the possibility that their own bodies will try to reject or destroy the transplant.
Rejection is part of the body s natural reaction to foreign invaders.
Much like fingerprints, MHAs are unique to an individual. To reduce the risk of rejection, physicians try to find donors whose MHAs are as genetically close to those of the recipient as possible. Nevertheless, most transplants, with the exception of those donated by identical twins, are recognized by the patient s immune system as foreign. Rejected transplants need to be surgically removed, and if the transplant is a life-sustaining organ such as a lung, liver, or heart, a patient may die before a replacement organ is found. In the past few decades, transplantation research has focused on identifying and understanding the mechanisms of transplant rejection so that it can be prevented and survival can be prolonged.