Ag-presenting Marilyn T cells directly inhibit memory T-cell proliferation in vivo. (A,B) Naive (10⁶) or memory (2 × 10⁶) CD45.1 CFSE-labeled Marilyn T cells were injected intravenously into CD45.2 female hosts. In parallel, CD45.1/2 Marilyn T cells were incubated in vitro overnight with CFSE-labeled H-Y peptide–loaded LPS-matured DCs or with DCs and an anti-TCR antibody. The next day, the 2 sets of in vitro–activated Marilyn T cells were FACS sorted according to CFSE and CD11c expression and injected into the footpad. Six days later, H-Y–loaded DCs were injected into the footpad to stimulate the T cells. CFSE patterns were studied in the DLN 6 days later. Dot plots on gated CD45.1⁺/CD45.2⁻/Vb6⁺/CD4⁺ cells are representative of 2 independent experiments with 2 mice in each.