We tested the ability of lewis (LEW; RT-1(1)) recipients to reject DA (RT-1av1) cardiac allografts following the selective elimination of alpha/beta T cells with the mouse monoclonal antibody R73. One group of adult rats (6 weeks old) received 1000 microg R73 i.p. on days 2 and 1 before transplantation, and 100 microg R73 every third day after transplantation up to day 18. Prolonged cardiac graft survival was noted (30, 30, 32, 51, 62, 108, > 500, > 500, > 500 days). Untreated controls (n = 10) rejected their grafts within 7 +/- 1 days. R73 therapy induced a dramatic decrease in alpha/beta T cells from 69% before treatment to 5% within the first 5 days, followed by an increase to 64% by day 8. The T cell increase was paralleled by the appearance of anti-mouse antibody. A second group of adult rats (10 weeks old) received the same treatment. These "older" recipients rejected their grafts within 20 +/- 5 days. Chronic R73 therapy from birth until the day of transplantation (100 microg R73 i.p. twice a week) resulted in graft survival of 37 +/- 9 days in eight animals. Two rats had a graft survival of more than 200 days. When chronic R73 therapy was continued to day 70 after transplantation, DA hearts were accepted well in all animals for more than 100 days. Alpha/beta T cells were virtually absent throughout the whole time of treatment. Antibodies against R73 were not detected. We concluded that selective elimination of alpha/beta T cells has a strong effect on allograft survival.
Age Factors Animals