Effect of interleukin-12 level augmented by Kakkon-to, a herbal medicine, on the early stage of influenza infection in mice.

Oral administration of Kakkon-to (KT) (5.0 mg per mouse three times daily), a herbal medicine, for 8 days from 1 day before influenza virus infection exhibited therapeutic efficacy in the infected mice. The effect of KT-treatment on the levels of cytokines, especially interleukin (IL)-12, was evaluated in the early phase of infection. KT was significantly effective in reducing the weight loss of infected mice, prolonging their survival times and reducing mortality. In infected mice administered with KT, virus yield in the bronchoalveolar lavage fluid (BALF) of lungs was significantly lower than that in the control on day 3 after infection. On day 2 after infection, only the level of IL-12 in the BALF increased significantly in KT-administered mice as compared with the control. Thus the significant enhancement of IL-12 correlated with the reduction of virus yields in BALF in the early phase of infection. This suggested a key role of IL-12 in the alleviation of influenza in the KT-treated mice. Copyright 2002 Elsevier Science B.V.