Failed versus enhanced induction of T-cell-mediated contact hypersensitivity by IL-21DCs or IL-15DCs in vivo. DCs, IL-15DCs, and IL-21DCs were labeled in vitro with FITC and injected into the hind footpad. (A) First challenge: 5 days later, mice were challenged with FITC painting to the ear and after 24, 48, and 72 hours the ear swelling reaction was analyzed. Painting of unsensitized mice served as control. (B) Second challenge: 14 days after the first challenge, the mice were painted again on the other ear and swelling was analyzed as before. (C) Migration of DCs was analyzed by FACS of the draining lymph nodes 24 hours after injection of 5 × 10⁵ FITC-labeled DCs. Cells were double stained for CD11c. The CD11c/FITC⁺ DCs as percent of total CD11c⁺ cells in the DLN are shown. Controls were injected with unlabeled DCs. The experiments were repeated at least twice; the mean ± SD of 12 mice is shown. Significance between IL-15DCs and IL-21DCs compared with DCs was calculated using Student t test (^*P ≤ .05; ^**P ≤ .01).