Reassessment of the role of CD8(+) T cells in the induction of allograft tolerance by donor-specific blood transfusion

Donor-specific allograft tolerance can be induced in adult rats by pregraft donor-specific blood transfusion (DST). We have previously shown that DST elicits in recipients the expansion of a donor-specific CD8(+) T cell clone displaying the V beta 18-D beta 1-J beta 2.7 TCR rearrangement, which rapi dly infiltrates allografts after transplantation, suggesting a regulatory f unction for this clone in DST-induced tolerance. In this study, recipients were pretreated before grafting, using an anti-CD8 monoclonal antibody to d eplete CD8(+) T cells. CD8 depletion before DST and transplantation abrogat ed allograft tolerance, and the CD8(+) T cell clone was absent from allogra fts. These effects were not observed when CD8 depletion was performed after DST but before transplantation. We conclude that CD8+ T cells play a role in the induction of allograft tolerance by DST.