Viral antigen and extensive division maintain virus-specific CD8 T cells during chronic infection

J Exp Med. 2007 Apr 16;204(4):941-9. doi: 10.1084/jem.20061937. Epub 2007 Apr 9.

Abstract

Efficient maintenance of memory CD8 T cells is central to long-term protective immunity. IL-7- and IL-15-driven homeostatic proliferation is essential for long-term memory CD8 T cell persistence after acute infections. During chronic infections, however, virus-specific CD8 T cells respond poorly to these cytokines. Yet, virus-specific CD8 T cells often persist for long periods of time during chronic infections. We have addressed this apparent paradox by examining the mechanism for maintaining virus-specific CD8 T cells during chronic infection. We find that homeostatic cytokines (e.g., IL-7/15), inflammatory signals, and priming of recent thymic emigrants are not sufficient to maintain virus-specific CD8 T cells over time during chronic infection. Rather, our results demonstrate that viral peptide is required for virus-specific CD8 T cell persistence during chronic infection. Moreover, this viral antigen-dependent maintenance results in a dramatically different type of T cell division than is normally observed during memory T cell homeostasis. Rather than undergoing slow, steady homeostatic turnover during chronic viral infection, CD8 T cells undergo extensive peptide-dependent division, yet cell numbers remain relatively stable. These results indicate that antigen-specific CD8 T cell responses during persisting infection are maintained by a mechanism distinct from that after acute infection.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD / metabolism
  • Antigens, Viral / immunology*
  • CD8-Positive T-Lymphocytes / cytology*
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / virology
  • Cell Division
  • Chronic Disease
  • Female
  • Interleukin-15 / metabolism
  • Interleukin-7 / metabolism
  • Lymphocytic Choriomeningitis / immunology*
  • Lymphocytic Choriomeningitis / metabolism
  • Lymphocytic Choriomeningitis / pathology*
  • Lymphocytic Choriomeningitis / virology
  • Lymphocytic choriomeningitis virus / immunology*

Substances

  • Antigens, CD
  • Antigens, Viral
  • Interleukin-15
  • Interleukin-7