Characteristic Immune Response in Peyer’s Patch Cells Induced by Oral Administration of Bifidobacterium Components

We demonstrate immunomodulatory effects, especially those involving murine intestinal IgA secretion, in Peyer's patch cells following oral administration of Bifidobacterium immunomodulator (BIM) derived from sonicated B. pseudocatenulatum 7041. BALB/c mice were administered BIM orally for 7 consecutive days. The PP cells demonstrated upregulated secretion of total IgA including BIM-specific IgA following BIM administration. In observing the response of PP cells co-cultured with BIM, we found enhanced secretion of interferon-γ (IFN-γ) and interleukin (IL)-6 in the CD4⁺ T cells. In contrast, IL-12 secretion by Thy1.2⁻ PP cells was enhanced, but secretion of IFN-γ, IL-5, and IL-6 was not significantly affected. Furthermore, the population of CD4⁺ CD45RB^high T cells in PP increased following oral administration of BIM. These data suggest that CD4⁺ T cells were affected by BIM administration. Overall, the results show that oral administration of BIM induced CD4⁺ PP cells to change their expression of cell surface antigen and cytokine production.