title: Virtual memory CD8 T cells display unique functional properties.
abstract: Previous studies revealed the existence of foreign antigen-specific memory phenotype CD8 T cells in unimmunized mice. Considerable evidence suggests this population, termed "virtual memory" (VM) CD8 T cells, arise via physiological homeostatic mechanisms. However, the antigen-specific function of VM cells is poorly characterized, and hence their potential contribution to immune responses against pathogens is unclear. Here we show that naturally occurring, polyclonal VM cells have unique functional properties, distinct from either naïve or antigen-primed memory CD8 T cells. In striking contrast to conventional memory cells, VM cells showed poor T cell receptor-induced IFN-γ synthesis and preferentially differentiated into central memory phenotype cells after priming. Importantly, VM cells showed efficient control of Listeria monocytogenes infection, indicating memory-like capacity to eliminate certain pathogens. These data suggest naturally arising VM cells display unique functional traits, allowing them to form a bridge between the innate and adaptive phase of a response to pathogens.
authors.affiliation: Center for Immunology, Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis, MN 55414, USA.
authors.forename: June-Yong
authors.initials: JY
authors.lastname: Lee
authors.forename: Sara E
authors.initials: SE
authors.lastname: Hamilton
authors.forename: Adovi D
authors.initials: AD
authors.lastname: Akue
authors.forename: Kristin A
authors.initials: KA
authors.lastname: Hogquist
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Jameson
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D007156:Immunologic Memory / Q000276:immunology*; D007371:Interferon-gamma / Q000096:biosynthesis*; D008089:Listeria monocytogenes / Q000276:immunology*; D008088:Listeriosis / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D060888:Real-Time Polymerase Chain Reaction; D013047:Specific Pathogen-Free Organisms
chemical_list: D007371:Interferon-gamma
keywords: homeostasis; lymphocyte
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