Compared to the results for the normal group, in the model group, the serum IFN-γ levels were distinctly lower (P < 0.01, Fig. 2B) and the expression of IL-4 and IgE was higher (P < 0.01, Fig. 2B), indicating that an imbalance in the Th1/Th2 ratio in allergic asthma rats. Here, IL4 is linked to allergic asthma.