title: The CD8+ T cell population elicited by recombinant adenovirus displays a novel partially exhausted phenotype associated with prolonged antigen presentation that nonetheless provides long-term immunity.
abstract: We have previously reported that the CD8+ T cell response elicited by recombinant adenovirus vaccination displayed a delayed contraction in the spleen. In our current study, we demonstrate that this unusual kinetic is a general phenomenon observed in multiple tissues. Phenotypic analysis of transgene-specific CD8+ T cells present 30 days postimmunization with recombinant adenovirus revealed a population with evidence of partial exhaustion, suggesting that the cells had been chronically exposed to Ag. Although Ag expression could no longer be detected 3 wk after immunization, examination of Ag presentation within the draining lymph nodes demonstrated that APCs were loaded with Ag peptide for at least 40 days postimmunization, suggesting that Ag remains available to the system for a prolonged period, although the exact source of this Ag remains to be determined. At 60 days postimmunization, the CD8+ T cell population continued to exhibit a phenotype consistent with partially exhausted effector memory cells. Nonetheless, these CD8+ T cells conferred sterilizing immunity against virus challenge 7-12 wk postimmunization, suggesting that robust protective immunity can be provided by CD8+ T cells with an exhausted phenotype. These data demonstrate that prolonged exposure to Ag may not necessarily impair protective immunity and prompt a re-evaluation of the impact of persistent exposure to Ag on T cell function.
authors.affiliation: Center for Gene Therapeutics, Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Teng-Chih
authors.initials: TC
authors.lastname: Yang
authors.forename: James
authors.initials: J
authors.lastname: Millar
authors.forename: Timothy
authors.initials: T
authors.lastname: Groves
authors.forename: Natalie
authors.initials: N
authors.lastname: Grinshtein
authors.forename: Robin
authors.initials: R
authors.lastname: Parsons
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Takenaka
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Wan
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Bramson
mesh_terms: D000256:Adenoviridae / Q000235:genetics / Q000276:immunology*; D019264:Adoptive Transfer; D000818:Animals; D017951:Antigen Presentation / Q000276:immunology*; D000956:Antigens, Viral / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D004527:Egg Proteins / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D005822:Genetic Vectors / Q000008:administration & dosage / Q000276:immunology*; D016130:Immunophenotyping; D008198:Lymph Nodes / Q000276:immunology; D051379:Mice; D010047:Ovalbumin / Q000276:immunology; D010446:Peptide Fragments; D013997:Time Factors; D019076:Transgenes
chemical_list: D000956:Antigens, Viral; D004527:Egg Proteins; C110366:OVA-8; D010446:Peptide Fragments; D010047:Ovalbumin