title: NK markers are expressed on a high percentage of virus-specific CD8+ and CD4+ T cells.
abstract: NK cells have been phenotypically defined by the expression of specific markers such as NK1.1, DX5, and asialo-GM1 (ASGM1). In addition to NK cells, a small population of CD3+ T cells has been shown to express these markers, and a unique subpopulation of NK1. 1+CD3+ T cells that expresses an invariant TCR has been named "NKT cells." Here, we describe NK marker expression on a broad spectrum of MHC class I- and MHC class II-restricted T cells that are induced after acute viral infection. From 5 to >500 days post lymphocytic choriomeningitis virus (LCMV) infection, more than 90% of virus-specific CD8+ and CD4+ T cells coexpress one or more of these three prototypical NK markers. Furthermore, in vivo depletion of NK cells with anti-ASGM1 Ab resulted in the removal of 90% of virus-specific CD8+ T cells and 50-80% of virus-specific CD4+ T cells. This indicates that studies using in vivo depletion to determine the role of NK cells in immune defense could potentially be misinterpreted because of the unintended depletion of Ag-specific T cells. These results demonstrate that NK Ags are widely expressed on the majority of virus-specific T cells and indicate that the NK and T cell lineages may not be as distinct as previously believed. Moreover, the current nomenclature defining NKT cells will require comprehensive modification to include Ag-specific CD8+ and CD4+ T cells that express prototypical NK Ags.
authors.affiliation: Department of Neuropharmacology, The Scripps Research Institute, La Jolla, CA 92037, USA. mslifka@scripps.edu
authors.forename: M K
authors.initials: MK
authors.lastname: Slifka
authors.forename: R R
authors.initials: RR
authors.lastname: Pagarigan
authors.forename: J L
authors.initials: JL
authors.lastname: Whitton
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000941:Antigens / Q000096:biosynthesis; D000950:Antigens, Ly; D000954:Antigens, Surface; D015415:Biomarkers / Q000032:analysis; D016516:CD4-CD8 Ratio; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism* / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism* / Q000821:virology; D018984:Epitopes, T-Lymphocyte / Q000096:biosynthesis*; D005677:G(M1) Ganglioside / Q000378:metabolism; D007156:Immunologic Memory; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism*; D007700:Kinetics; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D008212:Lymphocyte Depletion; D008217:Lymphocytic choriomeningitis virus / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D055651:NK Cell Lectin-Like Receptor Subfamily B; D014176:Protein Biosynthesis; D011506:Proteins; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism*
chemical_list: D000941:Antigens; D000950:Antigens, Ly; D000954:Antigens, Surface; D015415:Biomarkers; D018984:Epitopes, T-Lymphocyte; C527211:Klrb1c protein, mouse; D037181:Lectins, C-Type; D055651:NK Cell Lectin-Like Receptor Subfamily B; D011506:Proteins; D005677:G(M1) Ganglioside; C018835:asialo GM1 ganglioside