title: IL-21 deficiency influences CD8 T cell quality and recall responses following an acute viral infection.
abstract: CD4 T cells are principal producers of IL-21 and are often required for optimal CD8 T cell responses. Therefore, we investigated the importance of IL-21 in determining the phenotypic attributes, functional quality, and maintenance of antiviral CD8 T cells following acute infection with the prototypic mouse pathogen lymphocytic choriomeningitis virus. Previous reports have documented an obligatory role for IL-21 in sustaining CD8 T cell responses during chronic infections. Here we show that the requirements for IL-21 are less stringent following acute infections; however, in the absence of IL-21, the capacity of CD8 T cells to attain the polyfunctional trait of IL-2 production is consistently reduced during both the effector and memory phases. This is further supported by in vitro studies showing that the addition of IL-21 promotes the differentiation of IL-2-producing CD8 T cells. Although the generation of memory CD8 T cells, which are capable of mounting protective recall responses, proceeds independently of IL-21, we demonstrate that IL-21 does function to support secondary responses, especially under competitive conditions. Collectively, these studies highlight the potential roles of IL-21 in determining the quality of CD8 T cell responses postinfection.
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: John S
authors.initials: JS
authors.lastname: Yi
authors.forename: Jennifer T
authors.initials: JT
authors.lastname: Ingram
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Zajac
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002469:Cell Separation; D005434:Flow Cytometry; D007156:Immunologic Memory / Q000276:immunology; D007376:Interleukin-2 / Q000276:immunology; D007378:Interleukins / Q000172:deficiency* / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D008216:Lymphocytic Choriomeningitis / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D000098546:Interleukin-21
chemical_list: D007376:Interleukin-2; D007378:Interleukins; D000098546:Interleukin-21