Organ Transplant Rejections May Not Be Permanent

Live Science | Charles Q. Choi

Organ transplants can save lives, but patients sometimes reject their new organs. Now, experiments in mice surprisingly reveal that there may one day be ways to ensure that patients who previously rejected transplants will be able to accept future ones.

Organ rejection happens when the immune system sees a transplanted organ as foreign and attacks it. This response depends on a kind of immune cell known as T cells.

Doctors try to avoid transplant rejection by finding donors whose organs are molecularly compatible to those of patients, and by giving patients drugs that suppress their immune system by targeting T cells. But it's only very rarely that patients can stop using immune-suppressant drugs and tolerate the transplant.

Moreover, some patients reject their new organs — or "grafts," as they are also called — after months or even years of tolerating their transplants. This may be because a new infection makes a person's immune systems sensitive to the presence of foreign tissue, researchers say. The assumption was that in these cases, any subsequent transplants would also be quickly rejected, and that loss of tolerance is permanent because of the alert state of the immune system. Continue reading