title: CD4+ICOS+ T lymphocytes inhibit T cell activation 'in vitro' and attenuate autoimmune encephalitis 'in vivo'.
abstract: The inducible co-stimulator (ICOS, CD278) is essential to the efficient development of normal and pathological immune reactions. Since ICOS-deficient mice have enhanced susceptibility to experimental allergic encephalomyelitis (EAE), we have functionally analyzed a CD4+ICOS+ population comprising 6-15% of all CD4+ T cells in secondary lymphoid organs of unmanipulated wild-type mice and checked for their ability to suppress EAE. In C57BL/6 mice, CD4+ICOS+ cells were a major source of cytokines including IFN-gamma, IL-2, IL-4, IL-10 or IL-17A. Upon activation, these cells showed preferentially enhanced production of IL-4 or IL-10 but inhibited IFN-gamma production. In contrast, CD4+ICOS- cells mainly produced IFN-gamma. Interestingly, CD4+ICOS+ cells partially suppressed the proliferation of CD4+ICOS- or CD4+CD25- lymphocytes 'in vitro' by an IL-10-dependent mechanism. Furthermore, CD4+ICOS+ activated and expanded under appropriate conditions yielded a population enriched in cells producing IL-10 and T(h)2 cytokines that also suppressed the proliferation of CD4+CD25- lymphocytes. CD4+ICOS+ cells, before or after expansion in vitro, reduced the severity of EAE when transferred to ICOS-deficient mice. In the same EAE model, lymph node cells from ICOS-deficient mice receiving ICOS+ cells showed reduced IL-17A production and enhanced IL-10 secretion upon antigen activation in vitro. Thus, naturally occurring CD4+ICOS+ cells, expanded or not in vitro, are functionally relevant cells able of protecting ICOS-deficient mice from severe EAE.
authors.affiliation: Departamento de Inmunología, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, E-28040 Madrid, Spain. jmrojo@cib.csic.es
authors.forename: Jose M
authors.initials: JM
authors.lastname: Rojo
authors.forename: Eliana
authors.initials: E
authors.lastname: Pini
authors.forename: Gloria
authors.initials: G
authors.lastname: Ojeda
authors.forename: Raquel
authors.initials: R
authors.lastname: Bello
authors.forename: Chen
authors.initials: C
authors.lastname: Dong
authors.forename: Richard A
authors.initials: RA
authors.lastname: Flavell
authors.forename: Umberto
authors.initials: U
authors.lastname: Dianzani
authors.forename: Pilar
authors.initials: P
authors.lastname: Portolés
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis* / Q000235:genetics; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000637:transplantation; D049109:Cell Proliferation; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000276:immunology* / Q000628:therapy; D060889:Inducible T-Cell Co-Stimulator Protein; D016753:Interleukin-10 / Q000096:biosynthesis / Q000378:metabolism; D020381:Interleukin-17 / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; C556694:Icos protein, mouse; D060889:Inducible T-Cell Co-Stimulator Protein; D020381:Interleukin-17; D016753:Interleukin-10