The respiratory tract influenza virus infection model of Balb/c clonal mice was used to observe the changes in NK cell activity, IL 2 content, IFN γ induction, and the content of T cell subgroup. The treating group was given Qingfei decoction in a dose of 34.08 g/kg, and the control group was given a positive control drug. The results showed that there was a lineal relationship among IFN γ, IF 2 and NK cell activity, and that Qingfei decoction could enhance the activity NK cells and IL 2, in...