title: Normal development and activation but altered cytokine production of Fyn-deficient CD4+ T cells.
abstract: The Src family kinase Fyn is expressed in T cells and has been shown to phosphorylate proteins involved in TCR signaling, cytoskeletal reorganization, and IL-4 production. Fyn-deficient mice have greatly decreased numbers of NKT cells and have thymocytes and T cells with compromised responses following Ab crosslinking of their TCRs. Herein we have addressed the role of Fyn in peptide/MHC class II-induced CD4(+) T cell responses. In Fyn-deficient mice, CD4(+) T cells expressing the DO11.10 TCR transgene developed normally, and the number and phenotype of naive and regulatory DO11.10(+)CD4(+) T cells in the periphery were comparable with their wild-type counterparts. Conjugation with chicken OVA peptide 323-339-loaded APCs, and the subsequent proliferation in vitro or in vivo of DO11.10(+) Fyn-deficient CD4(+) T cells, was virtually indistinguishable from the response of DO11.10(+) wild-type CD4(+) T cells. Proliferation of Fyn-deficient T cells was not more dependent on costimulation through CD28. Additionally, we have found that differentiation, in vitro or in vivo, of transgenic CD4(+) Fyn-deficient T cells into IL-4-secreting effector cells was unimpaired, and under certain conditions DO11.10(+) Fyn-deficient CD4(+) T cells were more potent cytokine-producing cells than DO11.10(+) wild-type CD4(+) T cells. These data demonstrate that ablation of Fyn expression does not alter most Ag-driven CD4(+) T cell responses, with the exception of cytokine production, which under some circumstances is enhanced in Fyn-deficient CD4(+) T cells.
authors.affiliation: Department of Microbiology and Immunology, University of California, San Francisco, CA 94143, USA.
authors.forename: Alusha A
authors.initials: AA
authors.lastname: Mamchak
authors.forename: Brandon M
authors.initials: BM
authors.lastname: Sullivan
authors.forename: Baidong
authors.initials: B
authors.lastname: Hou
authors.forename: Linda M
authors.initials: LM
authors.lastname: Lee
authors.forename: Julia K
authors.initials: JK
authors.lastname: Gilden
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Krummel
authors.forename: Richard M
authors.initials: RM
authors.lastname: Locksley
authors.forename: Anthony L
authors.initials: AL
authors.lastname: DeFranco
mesh_terms: D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D000941:Antigens / Q000235:genetics / Q000276:immunology; D018106:CD28 Antigens / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology*; D049109:Cell Proliferation; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000276:immunology; D015847:Interleukin-4 / Q000235:genetics / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology
chemical_list: D000941:Antigens; D018106:CD28 Antigens; D000949:Histocompatibility Antigens Class II; D011948:Receptors, Antigen, T-Cell; D015847:Interleukin-4; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn