title: Oral antigen induces antigen-specific activation of intraepithelial CD4+ lymphocytes but suppresses their activation in spleen.
abstract: Intraepithelial lymphocytes (IELs) are considered to drive immune surveillance of the epithelial layer to the mucosa, which is initially exposed to exogenous antigens. However, how IELs are activated by orally administered antigens remains unclear. To clarify this mechanism, we fed ovalbumin (OVA) to T cell receptor transgenic (TCR-Tg) mice with OVA-specific MHC class II-restricted TCR and found that the cytotoxic activity of IELs was increased against both NK and LAK target cells, but notably reduced after depleting CD8 + IELs. Cytoplasmic staining showed that the production of IFN-gamma and IL-2 was increased in mice fed with OVA both in the supernatant of cultured IELs with immobilized anti-CD3 mAb and in fresh CD4+ IELs. In contrast, the cytotoxic activity against NK and LAK target cells and the production of IL-2 and IFN-gamma was decreased in splenic T cells from mice fed with OVA. However, when the splenic T cells from these mice were cultured with OVA and IL-2, IFN-gamma production recovered. The decreased response demonstrated the clonal anergy of T cells. Furthermore, tumor growth was enhanced in TCR-Tg mice carrying an OVA-transfected counterpart A20 B cell lymphoma (OVA-A20) and fed with OVA. These results indicate that the oral administration of soluble antigens can activate CD4+ IELs in an antigen-specific manner but induces hyporesponsiveness in the spleen. In addition, Th1-type cytokines produced by activated CD4+ IEL might provide a bystander effect on the cytotoxic activity of IELs.
authors.affiliation: Department of Microbiology, Kitasato University School of Medicine, Kanagawa, Japan. hidetama@med.kitasato-u.ac.jp
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Tamauchi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Takehito
authors.initials: T
authors.lastname: Sato
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hachimura
authors.forename: Matsuhisa
authors.initials: M
authors.lastname: Inoue
authors.forename: Shuichi
authors.initials: S
authors.lastname: Kaminogawa
authors.forename: Sonoko
authors.initials: S
authors.lastname: Habu
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000941:Antigens / Q000008:administration & dosage* / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D008213:Lymphocyte Activation; D051379:Mice; D008822:Mice, Transgenic; D009055:Mouth / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000941:Antigens