Factor-dependent expansion of CD8⁺ DNRII Tg T cells. (A) Purified, CFSE-labeled DNRII Tg T cells from 8- to 10-week-old mice were injected into DNRII Tg (right panels) or age-matched C57BL/6 host (left panels). Hosts were killed, and lymphocytes from lymph nodes were pooled and analyzed for CFSE⁺ T cells 2 weeks after injection. Data shown are from 2 representative mice. Mean of the percentage of CD8⁺ T cells in each peak is shown below the last row of profiles. (B) Purified, CFSE-labeled DNRII Tg T cells from 8- to 10-week-old mice were injected into IL-15 KO (right panels) or age-matched C57BL/6 host (left panels). Hosts were killed, and lymphocytes from lymph nodes were pooled and analyzed for CFSE⁺ T cells 2 weeks after injection. Lymphocytes from lymph nodes were analyzed by flow cytometric analysis for CFSE staining. Data shown are for CD8⁺ T cells from 3 representative mice. Mean of the percentage of CD8⁺ T cells in each peak is shown below the last row of profiles. (C) Purified, CFSE-labeled DNRII Tg T cells from 8- to 10-week-old mice were injected into IL-15 KO (right panels) or age-matched C57BL/6 hosts (left panels) with subcutaneously implanted mini-osmotic pumps containing either PBS (top panels) or IL-7 (bottom panels). Hosts were killed, and lymphocytes from lymph nodes were pooled and analyzed for CFSE⁺ T cells 2 weeks after injection. Data shown are for CD8⁺ T cells from 2 representative mice per group. Mean of the percentage of CD8⁺ T cells in each peak is shown below the last row of profiles. All experiments were repeated at least 3 times with similar results.