The induction of donor-specific unresponsiveness constitutes the most desirable means of
securing long-term graft survival, as it would spare the recipient from the deleterious effects
of global immunosuppression. Based on recent insights into the factors controlling both
intrathymic and extrathymic clonal deletion or inactivation of T cells, this objective can
potentially be accomplished by the direct inoculation of the thymus with alloantigen to
modulate T cell development at both the thymic and post-thymic level