Similar to the case in the mRNA expression level of IL-5 and IL-13 in allergic asthma (Fig. 1f), the percentages of IL-5+ and IL-13+ CD4+ Th cells were significantly lower in HDM-sensitized Tlr9−/− mice than in HDM-sensitized WT mice (Fig. 3c,d). This evidence concerns the gene TLR9 and allergic asthma.