SUCCESSFUL NERVE REGENERATION AND PERSISTENCE OF DONOR CELLS AFTER A LIMITED COURSE OF IMMUNOSUPPRESSION IN RAT PERIPHERAL-NERVE ALLOGRAFTS

Background. The origin of Schwann cells and effect of a Limited course of immunosuppression using cyclosporine (CsA) were examined in rat pe ripheral nerve allotransplants. Methods. Phenotypes of Schwann cells i n groups without, with continuing, and with Limited (12 weeks) CsA tre atment were examined immunohistochemically in allogeneically and synge neically transplanted animals from 4 to 36 weeks after transplantation . Results. In the group receiving no CsA, little nerve regeneration wa s obtained; donor Schwann cells were rejected and replaced by recipien t cells. In continuing and limited-course CsA groups, successful nerve regeneration was achieved at postoperative meek 36, as was also obser ved in the syngeneic group. Schwann cells in the continuing CsA group remained donor-derived. In the limited-course CsA group, graft rejecti on and loss of function occurred after the withdrawal of CsA, and dono r Schwann cells were replaced by recipient cells in the part of the gr aft where rejection had been complete. However, many donor Schwann cel ls remained at week 36, when the rejection response subsided, Conclusi on. Possible clinical use of a limited course of immunosuppression was supported by this demonstration of long term persistence of donor Sch wann cells.