CsA treatment inhibits CD8 T-cell tolerance. (A-D) WT B6 mice received 3 Gy TBI and anti-CD154 mAb followed by B10.A BMT. One group of mice was also treated with CsA for 14 days (n = 6-7/group; 1 representative of 3 experiments is shown). In the experiment shown in panel B, recipient CD8 T-cell depletion was performed in addition (n = 7-8/group). (A-B) Incidence of chimerism in different lineages is indicated. Chimerism in CD4 cells (not shown) was comparable with that in CD8 cells. A lineage was defined as chimeric when ≥ 5% donor cells were found in that lineage. Note that T-cell chimerism usually only begins to appear at 2 weeks after BMT and thereafter increases slowly, reflecting the long survival time of peripheral T cells and the slow peripheral repopulation from de novo thymopoiesis. (C) Recipient mice were euthanized at day 90 after BMT, and their splenocytes were used in a cell-mediated lympholysis assay to determine cytotoxicity against donor and third-party targets. CyA indicates cyclosporine A. (D) At day 1 after BMT, skin grafts were placed, and survival was followed until day 100 after grafting. Mean graft survival times were as follows: donor grafts 48 days with CsA vs indefinite without CsA, third-party grafts 29 days with CsA vs 22 days without CsA. (E-F) 2C/B6 syn-chimeric mice received 3 Gy TBI/anti-CD154 and B10.A BMT. One group of mice was also treated with CsA for 28 days (n = 10-11/group). (E) Levels of chimerism in mice that showed engraftment at 2 weeks are depicted over time for the B-cell lineage. (F) The percentage of 2C⁺CD8⁺ cells among peripheral blood lymphocytes is depicted over time.