Induction of operational tolerance to discordant dopaminergic porcine xenografts.
BACKGROUND: Porcine embryonic neural tissue transplanted intracerebrally could potentially relieve the symptoms of Parkinson's disease if the immune response toward the graft could be overcome. However, conventional immunosuppressive treatments have proven inefficient in preventing rejection. An alternative is blocking the costimulatory signals for lymphocyte activation. Treatment with cytotoxic T