Tolerogenic Protocol for Intestinal Transplantation

Abstract

Transplantation is standard therapy for many patients suffering from kidney, liver, or heart failure. In contrast, transplantation of the intestine remains a high-risk procedure, which is performed in a minority of patients with short bowel syndrome. The difficulty is the strong alloimmune response caused by intestinal grafts and the complications of the profound immunosuppression. We tested a new clinical immunomodulatory protocol using donor-specific blood transfusion, a strategy that was popular before the introduction of cyclosporine and was recently shown to promote development of regulatory cells. Low-dose steroids and low-dose tacrolimus were administered based on previous observations that tolerance requires an intact immune system, that overimmunosuppression is counterproductive, and that high doses of calcineurin inhibitors block development of regulatory cells whereas low doses promote it. Finally, inflammation within the intestinal graft was minimized to reduce the additional stimulants that the innate immunity of the transplanted intestine exert on the adaptive immune response. Under this protocol, freedom from rejection was achieved in four consecutive intestinal transplant recipients using extremely low immunosuppression.