Tracheal allotransplantation in beagle dogs without immunosuppressants

Background. The antigenicity of tracheal grafts is still unclear. We investigated the possibility of performing tracheal allotransplantation without immunosuppressants. Methods. Intrathoracic five-ring tracheal replacements were performed in beagle dogs without immunosuppressants (n = 18). The dogs were divided into 9 pairs, and grafts were exchanged within the pairs. In group 1 (n = 6), the paired dogs were blood relatives, whereas in group 2 (n = 12), the paired dogs were not related. Full-thickness skin transplantation was also performed in both groups. Results. In group 1, 5 animals survived uneventfully for more than 3 months. No stenosis was observed in any of the dogs. In group 2, the grafts were incorporated by the host trachea in 2 dogs. Four animals died of airway obstruction within 3 months. Moderate or slight airway stenosis was observed in 6 dogs. Rejection was confirmed by histologic examination. In both groups, all of the skin allografts were destroyed within 2 weeks. Conclusions. After tracheal allotransplantation, long-term survival was achieved, especially in recipient dogs that were blood relatives of donors. We conclude that it is possible to perform tracheal allotransplantation using histocompatible matched grafts without immunosuppressants.