Interaction between B7-H1 and PD-1 in lymphoid organs is sufficient to induce OT-1 T-cell anergy. B6 mice were given OT-1 cells prior to intravenous administration of 0.5 mg OVA peptide. On 0, 24, or 48 hours after OVA peptide injection, mice were given 100 μg intravenously of control hamster IgG, B7-H1 mAb (clone 10B5), or PD-1 mAb (clone G4). Second doses were administered 3 days after the first dose. Blood was taken from mice at the time points indicated, and the percentage of OT-1 cells observed in each mouse was analyzed by flow cytometry as described previously. The data shown are the means ± SD of 3 mice in each group and are representative of at least 3 independently performed experiments.