Loss of host axons in nerve allografts after abolishing immunological tolerance in rats

Because host axons regenerate through long nerve allografts and become ensheathed by allogeneic cells in tolerant rats, we determined what would happen to these axons if tolerance were abolished. This was achieved by inoculating lymphoid cells from specifically sensitized isogenic donors into tolerant hosts. As a consequence of the immunological reaction which ensued, the host axons in the graft degenerated, indicating that permanent immunosuppression is required to maintain these fibers.