Reisolation of mdm100-specific CTL activity from BMT recipients. C57BL/6 mice received a BMT from B10.A(4R) donors followed by injection of 4 × 10⁶ and 5 × 10⁶mdm100-specific CTL 1 and 10 days after the BMT (BMT+CTL group). Control mice received a BMT but no CTL (BMT group). Three weeks after the second CTL injection, mice were killed and cells isolated from the spleen (A), thymus (B), lymph nodes (C), and BM (D) were stimulated in vitro with irradiated RMA-S cells loaded with mdm100 peptides as described in Materials and Methods. Peptide-specific CTL activity was discovered in all tissues from BMT+CTL mice (A through D), and similar results were obtained in independent experiments. In contrast, no peptide-specific CTL activity was observed in tissues from BMT mice. ([E] shows a representative result obtained with BM cells. Similar results were obtained when spleen, thymus, and lymph nodes were analyzed.)