title: T-cell exhaustion due to persistent antigen: quantity not quality?
abstract: T-cell exhaustion is characterized by failure to respond to a persistent antigen and is a hallmark of chronic infections and cancer. Here, we discuss several recent reports on T-cell exhaustion, including one in this issue of the European Journal of Immunology where Richter et al. [Eur. J. Immunol. 42:2290-2304] examine the importance of the amount of persistent antigen versus the cell type presenting it to induce CD8(+)  T-cell exhaustion, and the consequences for host survival during chronic viral infection.
authors.affiliation: Division of Biological Sciences, University of California San Diego, La Jolla, San Diego, CA, USA. eizuniga@ucsd.edu
authors.forename: Elina I
authors.initials: EI
authors.lastname: Zuniga
authors.forename: James A
authors.initials: JA
authors.lastname: Harker
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002908:Chronic Disease; D006801:Humans; D051379:Mice; D014777:Virus Diseases / Q000276:immunology*; D014780:Viruses / Q000276:immunology*
chemical_list: D000956:Antigens, Viral