What is immune tolerance?

Immune tolerance has long been considered to be the “Holy Grail” of organ transplantation. It refers to the ability to train a recipient’s immune system to naturally recognize the donated organ as “self”. Normally, a transplant recipient’s immune system sees a donated organ as foreign and will attack it. To avoid organ rejection, anti-rejection drugs are used to suppress the transplant recipient’s immune system. These drugs must be taken for life and have significant risks and complications. Inducing immune tolerance in a transplant recipient eliminates the need to chronically suppress their immune system to prevent rejection of the donated organ, and avoids the many undesirable side effects associated with these drugs.