Experimental Study of Blood Typing in Immunosuppressant-free Tracheal Transplantation in Dogs

BACKGROUND: A previous report has noted that tracheal allotransplantation is possible using allografts without immunosuppressants. In the present study, we investigated whether blood typing is necessary in immunosuppressant-free tracheal allotransplantation in dogs. METHODS: In group 1, the blood types of paired dogs were mismatched (n=6, three pairs), while the blood types of paired dogs were matched in group 2 (n=6, three pairs). In paired dogs, an intrathoracic 5-ring tracheal segment was exchanged. No immunosuppressants were used. RESULTS: All animals survived for more than 8 weeks. In each group, different degrees of airway stenosis were observed in four dogs. However, no stenosis was observed in the other two dogs. Histologically, no vascular rejection was detected. Ciliated columnar epithelium covered the inner surface of the implanted graft in the long-term survival cases. CONCLUSIONS: In immunosuppressant-free tracheal allotransplantation, no hyperacute rejection occurred in any recipient dog whose blood type was mismatched with the donor. Blood typing was not the key factor to successful immunosuppressant-free tracheal allotransplantation. Immunosuppressant-free tracheal allotransplantation may be possible using mismatched blood type tracheal grafts.