R-848 enhances the induction of CHS. Mice were sensitized by epicutaneous application of DNFB and FITC with the concentrations indicated (A and B, respectively). R-848 was injected intraperitoneally during the sensitization process. Six days (DNFB) and 7 days (FITC) later, the right ear was challenged with the respective hapten, and CHS was determined as increase in ear thickness compared with the vehicle-treated ear. Immediately after measuring ear thickness, ears were harvested for immunohistochemistry and stained with anti-Gr-1 (C). Corresponding groups in panels B and C are labeled i-iv. Data represent means of 5 to 7 mice per group. Each experiment was repeated at least 2 times. The bar represents 100 μm (left column) or 50 μm (right column). The P values for the relevant groups are indicated. Values in panels A and B represent the means ± standard deviation (SD) of all mice measured in each group. ^*Significant difference.