THE FATE OF SCHWANN-CELLS IN PERIPHERAL-NERVE ALLOGRAFTS

The phenotype of Schwann cells, whether of host or donor origin, in ne rve allografts has been a source of debate. The origin of Schwann cell s in peripheral nerve allografts under conditions of no, temporary or continuous immunosuppression was assessed by immunohistochemistry. We hypothesized that host-derived Schwann cells would replace rejected fo reign donor Schwann cells after withdrawal of immunosuppression. A mur ine model of nerve transplantation to normal (wildtype) hosts from don or Shiverer mice, a mutant whose Schwann cells are deficient in myelin basic protein, was used and antibody reactivity against myelin basic protein was employed to ascertain the identity of Schwann cells in the nerve allograft. Without immunosuppression, donor Shiverer Schwann ce lls were rejected and the nerve graft morphology was restored by host- derived Schwann cells. With continuous immunosuppression, donor Shiver er Schwann cells persisted in the graft segment, associated with a chr onic rejection phenomenon. The latter allowed migration of host-derive d Schwann cells, over time, into the graft segment in approximately ha lf the cases. After withdrawal of finite (6 weeks) immunosuppression, a rejection response eliminated donor Schwann cells. Replacement by ho st Schwann cells ensued as was hypothesized.