CTLA4/B7.1/B7.2 and PD-1 are CD8 T cell-intrinsically required for peripheral tolerance induced by anti-CD40L and allogeneic BMT. K^bD^b MHC class I–deficient animals were used as recipients of 3 Gy TBI/anti-CD40L/allo-BMT with B10.A BMCs. Adoptive transfer of 6-9 × 10⁶ purified recipient-type CD8 T cells was performed by intravenous injection at the time of allo-BMT. Dashed gray lines represent CTLA4/B7.1/B7.2 KO (A) or PD-1 KO (B) CD8 T cells, while solid black lines represent WT CD8 T cells. The percentage of donor chimerism in the B-cell lineage of the peripheral blood is shown. The dotted line at 5% donor chimerism represents our cutoff for calling an animal a chimera. N = 6-8 mice per group.