ENHANCEMENT OF IMMUNOGLOBULIN-A PRODUCTION IN PEYERS-PATCHES BY ORAL-ADMINISTRATION OF A TRADITIONAL CHINESE MEDICINE, XIAO-CHAI-HU-TANG (SHOSAIKO-TO)

The Peyer's patches contain a large number of precursor cells committe d to the production of immunoglobulin A (IgA) and play an important ro le in IgA response in the mucosal immune system. We investigated the i nduction of IgA producing cells in Peyer's patches by plaque forming c ell assay after oral administration of a traditional Chinese herbal me dicine, Xiao-chai-hu-tang (Japanese name: Shosaiko-to). The number of total IgA producing cells in the Peyer's patches detected by the prote in-A plaque assay was increased about two-fold by Shosaiko-to administ ration and the numbers of both anti-SRBC and anti-HRBC IgA producing c ells were also increased by such a treatment. On the other hand, when SRBC alone were administered orally, only the number of anti-SRBC IgA producing cells was increased. Further, we examined T-cell subpopulati ons in the gut-associated lymphoid tissues after oral administration o f Shosaiko-to by flowcytometry. Marked alternations in T cell subpopul ations were not detected in the Peyer's patches, though TcRgammadeltaT-cells in the intraepithelial lymphocytes and Thy1.2-TcRalphabeta+T c ells in the mesenteric lymph nodes were slight increased. These result s showed that orally administered Shosaiko-to acts as a polyclonal B-c ell activator which induces IgA production in the mucosal immune syste m.