Induction of interferon after administration of a traditional Chinese medicine, xiao-chai-hu-tang (shosaiko-to).

We examined the ability of a traditional chinese herbal medicine, xiao-chai-hu-tang (Japanese name: shosaiko-to) to induce IFN in mice. A maximum activity (105 units/ml) of interferon (IFN) appeared in the serum of mice 16 h after intraperitoneal (i.p.) treatment with 250 mg/kg of shosaiko-to. Addition of polymyxin B did not abrogate the ability of shosaiko-to to induced serum IFN. The IFN was identified as IFN-alpha/beta by neutralizing test using anti-IFN alpha/beta antibodies. Pretreatment of mice with carrageenan suppressed the IFN induction by shosaiko-to, whereas the IFN induction by shosaiko-to was impaired neither in mice treated with anti-asialo-GM1 antibody nor in T-cell-deficient athymic nude mice. IFN was produced in vitro by spleen cells obtained from shosaiko-to treated mice. Moreover, spleen cells from untreated mice could also produce IFN when they were cultured with shosaiko-to. Additionally, serum IFN was also induced by the adoptive transfer of spleen cells from shosaiko-to treated mice to normal mice. On the other hand, peroral administration of shosaiko-to also induced IFN-alpha/beta in the serum. While IFN activity induced by i.p. administration of shosaiko-to declined after repeated treatments, the activity induced by its peroral administration did not decline during a long term treatment. These results showed that shosaiko-to is an IFN-alpha/beta inducer capable of repeated peroral administration.