Functional CD8 T cell memory responding to persistent latent infection is maintained for life

J Immunol. 2011 Oct 1;187(7):3759-68. doi: 10.4049/jimmunol.1100666. Epub 2011 Sep 2.

Abstract

Aging is associated with depressed naive T cell responses, but it is less clear whether T cell memory established early in life also becomes impaired with age. This is particularly important for T cells responding to latent persistent infection, which need to remain functional and capable of controlling the infection over the lifetime; however, repeated stimulation over the lifetime may dysregulate their maintenance or function, potentially contributing to impaired immunity in the elderly. Systemic infection with HSV-1, a persistent latent virus, is associated with memory inflation of virus-specific CD8 T cells. We tested how these inflated memory cells are maintained from adulthood into old age. We found no significant differences in the numbers (i.e., blood, spleen), ex vivo Ag-specific IFN-γ production, and in vivo recall response to HSV-1 (i.e., proliferation, IFN-γ production, cytolysis) between adult and old memory T cells. There was a discrete shift from dominantly effector memory phenotype in the adults to a central memory-like phenotype in the old mice, with fewer old cells expressing the killer cell lectin-like receptor G1 (KLRG1). Adult and old KLRG1(+) memory CD8 T cells were functionally identical: both produced IFN-γ but could minimally proliferate in response to viral challenge. Interestingly, regardless of age, KLRG1(+) cells retained the ability to proliferate and survive in response to homeostatic signals, both in vitro (culture with IL-7 and IL-15) and in vivo (expansion following transfer into lymphopenic recipients). This finding demonstrates that functional effector memory T cells, including those expressing KLRG-1, are maintained and are functional for life, despite the presence of persistent viral infection.

Publication types

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

MeSH terms

  • Adoptive Transfer
  • Aging / immunology*
  • Animals
  • CD8-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / metabolism
  • Cell Separation
  • Flow Cytometry
  • Herpes Simplex / immunology
  • Herpesvirus 1, Human / immunology
  • Immunologic Memory / immunology*
  • Lectins, C-Type
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Phenotype
  • Receptors, Immunologic / immunology
  • Receptors, Immunologic / metabolism
  • T-Lymphocyte Subsets / immunology*
  • T-Lymphocyte Subsets / metabolism
  • Virus Latency / immunology*

Substances

  • Klrg1 protein, mouse
  • Lectins, C-Type
  • Receptors, Immunologic