Full responsiveness of remaining donor-reactive T cells to donor Ag 18 days after DST. Splenocytes from 2C_F1 mice either untreated (◊) or 18 days after DST (□) were stimulated by irradiated (20 Gy) splenocytes from BYJ mice in α-MEM supplemented with 10% FCS and 30 U/mL rIL-2. In the top panel, proliferation ([³H] TdR incorporation) was measured after a 3.5-day culture. Data are plotted as cpm versus number of 1B2⁺CD8⁺/well. Each data point represents five replicates. In the bottom panel, percentage lysis of specific L^d target cells (open symbols) was measured by⁵¹Cr release assay after a 5-day culture. Data are plotted as percentage specific killing versus number of 1B2⁺CD8⁺ cells/well. These results represent four independent experiments. Killing of third-party control (H-2^K) target cells by the highest number of effector cells is shown in solid symbols. Each data represents five replicates. Similar results were obtained at 35 days after DST.