title: Age-related CD8 T cell clonal expansions constrict CD8 T cell repertoire and have the potential to impair immune defense.
abstract: Peripheral T cell diversity is virtually constant in the young, but is invariably reduced in aged mice and humans. CD8+ T cell clonal expansions (TCE) are the most drastic manifestation of, and possible contributors to, this reduced diversity. We show that the presence of TCE results in reduced CD8+, but not CD4+, T cell diversity, and in functional inability to mobilize parts of the CD8+ T cell repertoire affected by TCE. In the model of herpes simplex virus (HSV)-1 infection of B6 mice, >90% of the responding CD8+ T cells use Vbeta10 or Vbeta8 and are directed against a single glycoprotein B (gB498-505) epitope, gB-8p. We found that old animals bearing CD8+ TCE within Vbeta10 or Vbeta8 families failed to mount an effective immune response against HSV-1, as judged by reduced numbers of peptide-major histocompatibility complex tetramer+ CD8 T cells and an absence of antiviral lytic function. Furthermore, Vbeta8 TCE experimentally introduced into young mice resulted in lower resistance to viral challenge, whereas Vbeta5+ TCE induced in a similar fashion did not impact viral resistance. These results demonstrate that age-related TCE functionally impair the efficacy of antiviral CD8+ T cell immunity in an antigen-specific manner, strongly suggesting that TCE are not the mere manifestation of, but are also a contributing factor to, the immunodeficiency of senescence.
authors.affiliation: Vaccine and Gene Therapy Institute, Oregon Health & Science University, West Campus, 505 NW 185th Ave., Beaverton, OR 97006, USA.
authors.forename: Ilhem
authors.initials: I
authors.lastname: Messaoudi
authors.forename: Joël
authors.initials: J
authors.lastname: Lemaoult
authors.forename: Jose A
authors.initials: JA
authors.lastname: Guevara-Patino
authors.forename: Beatrix M
authors.initials: BM
authors.lastname: Metzner
authors.forename: Janko
authors.initials: J
authors.lastname: Nikolich-Zugich
mesh_terms: D000375:Aging / Q000276:immunology*; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology* / Q000276:immunology; D022801:Complementarity Determining Regions / Q000235:genetics; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D017422:Sequence Analysis, DNA; D018139:Simplexvirus / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology
chemical_list: D022801:Complementarity Determining Regions; D011948:Receptors, Antigen, T-Cell