Long-term residence of a graft is an insufficient stimulus for the induction of tolerance. Investigating the role of cyclosporine in class I-disparate heart grafts in the rat.

This study demonstrates that the induction of tolerance is possible across a class I only antigenic barrier that fails to produce heart graft rejection. However, the long-term residence alone of such a graft per se, does not necessarily lead to the establishment of systemic tolerance in the recipient. The important finding in this study with regard to the biology of allograft tolerance, is that while the class I antigen provides the stimulus, its presence alone is not sufficient for the induction of tolerance; indeed, the action of the Cyclosporine A (CyA) is a necessary adjunct to its induction.