title: Memory CD8+ T cells provide an early source of IFN-gamma.
abstract: During the non-Ag-specific early phase of infection, IFN-gamma is believed to be primarily provided by NK and NKT cells in response to pathogen-derived inflammatory mediators. To test whether other cell types were involved in early IFN-gamma release, IFN-gamma-producing cells were visualized in spleens and lymph nodes of LPS-injected mice. In addition to NK and NKT cells, IFN-gamma was also detected in a significant fraction of CD8(+) T cells. CD8(+) T cells represented the second major population of IFN-gamma-producing cells in the spleen ( approximately 30%) and the majority of IFN-gamma(+) cells in the lymph nodes ( approximately 70%). LPS-induced IFN-gamma production by CD8(+) T cells was MHC class I independent and was restricted to CD44(high) (memory phenotype) cells. Experiments performed with C3H/HeJ (LPS-nonresponder) mice suggested that CD8(+) T cells responded to LPS indirectly through macrophage/dendritic cell-derived IFN-alpha/beta, IL-12, and IL-18. IFN-gamma was also detected in memory CD8(+) T cells from mice injected with type I IFN or with poly(I:C), a synthetic dsRNA that mimics early activation by RNA viruses. Taken together, these results suggest that in response to bacterial and viral products, memory T cells may contribute to innate immunity by providing an early non-Ag-specific source of IFN-gamma.
authors.affiliation: Department of Pathology, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Taku
authors.initials: T
authors.lastname: Kambayashi
authors.forename: Erika
authors.initials: E
authors.lastname: Assarsson
authors.forename: Aron E
authors.initials: AE
authors.lastname: Lukacher
authors.forename: Hans-Gustaf
authors.initials: HG
authors.lastname: Ljunggren
authors.forename: Peter E
authors.initials: PE
authors.lastname: Jensen
mesh_terms: D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D002478:Cells, Cultured; D018920:Coculture Techniques; D003713:Dendritic Cells / Q000276:immunology; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000502:physiology; D007156:Immunologic Memory; D007274:Injections, Intraperitoneal; D007370:Interferon Type I / Q000502:physiology; D007371:Interferon-gamma / Q000096:biosynthesis*; D018664:Interleukin-12 / Q000502:physiology; D020382:Interleukin-18 / Q000502:physiology; D007399:Interphase / Q000276:immunology; D008070:Lipopolysaccharides / Q000008:administration & dosage; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013154:Spleen / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D013997:Time Factors
chemical_list: D015395:Histocompatibility Antigens Class I; D007370:Interferon Type I; D020382:Interleukin-18; D008070:Lipopolysaccharides; D018664:Interleukin-12; D007371:Interferon-gamma