Background. The major limitation preventing expansion of laryngeal transplantation as a therapeutic modality is the necessity of lifelong immunosuppression. In this report, we describe an immunomodulatory strategy for tolerance induction in laryngeal allotransplantation that permits escape from chronic immunosuppression. Materials and Methods. Larynges were transplanted from Lewis-Brown-Norway (RT11/n, F1) donors to Lewis (RT1 1) recipients. Recipients received 7 days of treatment with tacrolimus and mouse anti-rat αβ T-cell-receptor (TCR) monoclonal antibodies. Histology, mixed lymphocyte reaction (MLR), skin grafting, and flow cytometry assessed functional tolerance, efficacy of immunodepletion, and donor-specific chimerism. Results. All 10 recipients survived until sacrifice at 100 days. Histology suggested functional allograft tolerance. Skin grafting, MLR, and flow cytometry revealed that tolerance is neither donor-specific nor related to systemic immunocompromise. Conclusions. In this rat laryngeal-transplantation model, functional tolerance was induced under combined tacrolimus and αβ TCR protocol. Mechanisms responsible for this tolerance induction require future elucidation.
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