A characterization of the nature and control of cellular allograft rejection.

The mechanism of cellular rejection has been analyzed. The cells infiltrating rat cardiac allografts have been recovered and identified. An important role for cytotoxic T lymphocytes in cellular rejection has been discerned. The entrapment of cytotoxic T lymphocytes within rejecting grafts is not rigorously dependent upon antigen recognition. The cellular processes by which cytotoxic T lymphocytes destroy target cells have been determined in part. Cellular levels of the 3',5' cyclic nucleotides modulate this process. Elevations in cellular levels of cyclic AMP inhibit cytotoxicity whereas increased cyclic GMP stimulates augmented cytotoxicity.