TLR4 and allergic asthma: The results showed that, compared with WT mice, tlr2−/−, and tlr4−/− mice exhibited increased infiltration of leukocytes, especially asthma-related eosinophils, in alveoli (Figures 1C,D), and IgE level in serum was increased significantly in tlr2−/− and tlr9−/− mice after allergic asthma establishment (Figure 1E).