Fig. 6.

TRI-MP imparts donor-specific tolerance to rat hindlimb allograft recipients. (A and B) To test for donor antigen–specific tolerance in vivo, TRI-MP–treated animals with long-term surviving grafts were challenged with full-thickness nonvascularized skin grafts from BN and WF donors. TRI-MP–treated animals accepted BN grafts (as evidenced by wound healing and hair growth), but failed to accept WF grafts (as evidenced by extensive graft necrosis resulting in an eschar). Histological evaluation of the BN skin graft reveals an intact epidermal layer with normal tissue architecture. (Scale bar, 100 μm.) (C) CD4⁺ CD25^hi Tregs isolated from TRI-MP–treated animals (n = 4–5, POD > 300) were cocultured with CD4⁺ CD25^– Tconvs purified from naïve LEW rats and then stimulated with either donor BN or third-party WF splenocytes. Tregs isolated from TRI-MP–treated animals were more effective at suppressing BN-induced proliferation than WF-induced proliferation. Significant difference is indicated by **P < 0.01.