Interleukin-6 is crucial for recall of influenza-specific memory CD4 T cells

PLoS Pathog. 2008 Feb 29;4(2):e1000006. doi: 10.1371/journal.ppat.1000006.

Abstract

Currently, our understanding of mechanisms underlying cell-mediated immunity and particularly of mechanisms that promote robust T cell memory to respiratory viruses is incomplete. Interleukin (IL)-6 has recently re-emerged as an important regulator of T cell proliferation and survival. Since IL-6 is abundant following infection with influenza virus, we analyzed virus-specific T cell activity in both wild type and IL-6 deficient mice. Studies outlined herein highlight a novel role for IL-6 in the development of T cell memory to influenza virus. Specifically, we find that CD4+ but not CD8+ T cell memory is critically dependent upon IL-6. This effect of IL-6 includes its ability to suppress CD4+CD25+ regulatory T cells (Treg). We demonstrate that influenza-induced IL-6 limits the activity of virus-specific Tregs, thereby facilitating the activity of virus-specific memory CD4+ T cells. These experiments reveal a critical role for IL-6 in ensuring, within the timeframe of an acute infection with a cytopathic virus, that antigen-specific Tregs have no opportunity to down-modulate the immune response, thereby favoring pathogen clearance and survival of the host.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD4-Positive T-Lymphocytes / immunology*
  • CD4-Positive T-Lymphocytes / metabolism
  • CD4-Positive T-Lymphocytes / virology
  • CD8-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / metabolism
  • CD8-Positive T-Lymphocytes / virology
  • Cells, Cultured
  • Female
  • Flow Cytometry
  • Gene Silencing
  • Immunologic Memory
  • Influenza A virus / immunology*
  • Interleukin-6 / physiology*
  • Lung / virology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Orthomyxoviridae Infections / immunology*
  • Orthomyxoviridae Infections / metabolism
  • Spleen / drug effects
  • Spleen / immunology
  • Spleen / virology
  • T-Lymphocytes, Cytotoxic / immunology
  • T-Lymphocytes, Regulatory / immunology*
  • T-Lymphocytes, Regulatory / metabolism
  • T-Lymphocytes, Regulatory / virology
  • Tumor Necrosis Factor-alpha / metabolism
  • Viral Load

Substances

  • Interleukin-6
  • Tumor Necrosis Factor-alpha