Intra-tracheal delivery of IL-10 gene plasmid can suppress AHR and airway eosinophilic inflammation in OVA-sensitized mice in a dose-dependent manner. Mice were sensitized and boosted as described in Fig. 1. On day 27 and 28, some mice received different doses of IL-10 gene plasmid DNA liposome complex by intra-tracheal injection (pIL-10-low: 2.5 μg; pIL-10-med: 10 μg; pIL-10-hi: 20 μg). Then, mice were challenged with 100 μg OVA by intranasal administration on day 29, and 30. On day 31, mice were analyzed. (A) AHR to Mch was measured as described in Material and Methods (n= 4–7 per group). The columns and error bars represent mean ± SEM for each group. * P < 0.05, ** P <0.01 compared with the value of positive controlgroup. (B) Bronchoalveolar lavage fluid (BALF) was collected two days after the last OVA challenge of each group of mice (n = 4–7). The cell compositions in BALF were analyzed. The columns and error bars represent mean ± SEM for each group.