title: The role of ICOS in directing T cell responses: ICOS-dependent induction of T cell anergy by tolerogenic dendritic cells.
abstract: Tolerogenic dendritic cells (DC) play an important role in maintaining peripheral T cell tolerance in steady-state conditions through induction of anergic, IL-10-producing T cells with suppressive properties. ICOS, an activation-induced member of the CD28 family on T cells, is involved in the induction of IL-10, which itself could contribute to induction of anergy and development of suppressive T cells. Therefore, we analyzed the functional role of ICOS in the differentiation process of human CD4(+) T cells upon their interaction with tolerogenic DC. We compared the functional properties of CD4(+) T cells from healthy volunteers and ICOS-deficient patients after stimulation with tolerogenic DC. We report that induction of T cell anergy and suppressive capacity is completely blocked after knockdown of ICOS expression in T cells as well as after blocking of ICOS-ICOS ligand interaction in DC/T cell cocultures. Moreover, CD4(+) T cells from ICOS-deficient patients were completely resistant to anergy induction and differentiation into suppressive T cells even after supplementation of IL-10. Furthermore, ICOS/ICOS ligand interaction stabilizes IL-10R expression on T cells and thus renders them sensitive to IL-10 effects. Taken together, these results indicate a crucial role for ICOS in the induction of peripheral tolerance maintained by tolerogenic DC mediated mostly via an IL-10-independent mechanism.
authors.affiliation: Department of Dermatology, University of Mainz, Mainz, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Tuettenberg
authors.forename: Eva
authors.initials: E
authors.lastname: Huter
authors.forename: Mario
authors.initials: M
authors.lastname: Hubo
authors.forename: Julia
authors.initials: J
authors.lastname: Horn
authors.forename: Jürgen
authors.initials: J
authors.lastname: Knop
authors.forename: Bodo
authors.initials: B
authors.lastname: Grimbacher
authors.forename: Richard A
authors.initials: RA
authors.lastname: Kroczek
authors.forename: Sabine
authors.initials: S
authors.lastname: Stoll
authors.forename: Helmut
authors.initials: H
authors.lastname: Jonuleit
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics / Q000502:physiology*; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D017635:Clonal Anergy / Q000235:genetics / Q000276:immunology*; D018920:Coculture Techniques; D017074:Common Variable Immunodeficiency / Q000235:genetics / Q000276:immunology / Q000473:pathology; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D055785:Gene Knockdown Techniques; D006801:Humans; D060889:Inducible T-Cell Co-Stimulator Protein; D016753:Interleukin-10 / Q000502:physiology; D008213:Lymphocyte Activation / Q000235:genetics; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology / Q000378:metabolism / Q000473:pathology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; C556692:ICOS protein, human; D060889:Inducible T-Cell Co-Stimulator Protein; D016753:Interleukin-10