Homologous nerve transplantation and immunosuppression in rabbits

Homologous nerve transplantation is a logical method of bridging major nerve defects but its usefulness is negated by immune rejection. The discovery of an effective method of immunosuppression would allow utilisation of this technique. The present study compared the effects of irradiation, dexamethasone, and chloramphenicol in homologous nerve transplantation. Segments of homologous sciatic nerve were implanted into the dorsal subcutaneous (s.c.) tissues of 83 rabbits. In one group the graft was irradiated in vitro before implantation and in other groups the recipient rabbits received either dexamethasone or chloramphenicol systemically for up to 3 weeks after implantation. The transplanted nerve segments were removed at different time intervals and examined for signs of rejection. In conclusion, rejection commenced during the 1st week and peaked during the 3rd week. In the control group without immunosuppressant, all animals exhibited severe rejection. Both pre-implantation irradiation of the grafts at 450 rad dose-level and systemic chloramphenicol at 100 mg/kg/day were found to completely suppress rejection. These methods were considerably more effective than conventional steroids. Thus, the idea of a "nerve bank" is postulated.