Role of B-lymphocytes in the immunopharmacological effects of a traditional Chinese medicine, xiao-chai-hu-tang (shosaiko-to).

We previously reported that a traditional Chinese medicine, Xiao-chai-hu-tang (Japanese name: Shosaiko-to), induced interferon (IFN) activity in the serum of mice after intraperitoneal (i.p.) administration. In the present study in which murine spleen cells were cultured in vitro with Shosaiko-to, B-cells isolated by anti-immunoglobulin-coated plates were confirmed to generate IFN in response to Shosaiko-to stimulation. IFN activity was induced in the serum after i.p. administration of Glycyrrhizae radix, Scutellariae radix, Bupleuri radix and Pinelliae tuber which are included in Shosaiko-to as its constituent. Such an IFN-inducing activity was confirmed to exist in methanol-insoluble fractions of these extracts derived from Shosaiko-to and these constituents but not in methanol-soluble fractions. These four extracts as well as Shosaiko-to, induced interleukin 6 (IL-6) in the serum after the administration. In in vitro stimulation of spleen cells, Shosaiko-to and extracts of Glycyrrhizae radix, Bupleuri radix and Pinelliae tuber showed mitogenic activity, but an extract of Scutellariae radix with in vivo IFN-inducing activity did not. B-cells appear to participate in the immunopharmacological effects of Shosaiko-to through mitogenic activity, IFN induction and the effect of IL-6.