CD4+ T cell immunity to Salmonella is transient in the circulation

PLoS Pathog. 2021 Oct 25;17(10):e1010004. doi: 10.1371/journal.ppat.1010004. eCollection 2021 Oct.

Abstract

While Salmonella enterica is seen as an archetypal facultative intracellular bacterial pathogen where protection is mediated by CD4+ T cells, identifying circulating protective cells has proved very difficult, inhibiting steps to identify key antigen specificities. Exploiting a mouse model of vaccination, we show that the spleens of C57BL/6 mice vaccinated with live-attenuated Salmonella serovar Typhimurium (S. Typhimurium) strains carried a pool of IFN-γ+ CD4+ T cells that could adoptively transfer protection, but only transiently. Circulating Salmonella-reactive CD4+ T cells expressed the liver-homing chemokine receptor CXCR6, accumulated over time in the liver and assumed phenotypic characteristics associated with tissue-associated T cells. Liver memory CD4+ T cells showed TCR selection bias and their accumulation in the liver could be inhibited by blocking CXCL16. These data showed that the circulation of CD4+ T cells mediating immunity to Salmonella is limited to a brief window after which Salmonella-specific CD4+ T cells migrate to peripheral tissues. Our observations highlight the importance of triggering tissue-specific immunity against systemic infections.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CD4-Positive T-Lymphocytes / immunology*
  • Female
  • Immunologic Memory / immunology*
  • Liver / immunology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Salmonella Infections, Animal / immunology*
  • Salmonella typhimurium / immunology