Regulation of T cells is dependent on contact with the infused allogeneic CD8α⁺ DCs. BALB/c mice were vaccinated with B6 H2-Ab1^−/− BM-derived CD8α⁺ DCs or CD8α⁻ DCs as in “Vaccination protocol.” T cells were harvested from these BALB/c animals and cultured for 72 hours with syngeneic or WT B6 allogeneic irradiated (3000 cGy) splenocytes and analyzed for proliferation after [³H] thymidine incorporation. P = not significant between the groups. Data are from one of 2 similar experiments.