Potential of costimulation-based therapies for composite tissue allotransplantation.

Clinical success has not been routinely achieved for composite tissue allotransplantation (CTA). Although most of the technical details of CTA have been overcome, the immunological aspects of these procedures have proved complex. Many traumatic conditions requiring CTA contraindicate acute global immunosuppression. Moreover, the risk of long-term immunosuppression is difficult to reconcile with non-life-threatening defects that can be adequately palliated. Recently, several successful immunomodulating strategies have been introduced for solid organ transplantation. They include therapies that alter costimulatory signals at engraftment. One approach, using treatment with a monoclonal antibody directed against CD154, has shown promise in rodent and nonhuman primate models and is discussed as a potential strategy for CTAs.