Culling of activated CD4 T cells during typhoid is driven by Salmonella virulence genes

Aparna Srinivasan, Minelva Nanton, Amanda Griffin, Stephen J Mcsorley

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Pathogen-specific CD4 T cells are activated within a few hours of oral Salmonella infection and are essential for protective immunity. However, CD4 T cells do not participate in bacterial clearance until several weeks after infection, suggesting that Salmonella can inhibit or evade CD4 T cells that are activated at early time points. Here, we describe the progressive culling of initially activated CD4 T cells in Salmonella-infected mice. Loss of activated CD4 T cells was independent of early instructional programming, T cell precursor frequency, and Ag availability. In contrast, apoptosis of Ag-specific CD4 T cells was actively induced by live bacteria in a process that required Salmonella pathogenicity island-2 and correlated with increased expression of PD-L1. These data demonstrate efficient culling of initially activated Ag-specific CD4 cells by a microbial pathogen and document a novel strategy for bacterial immune evasion.

Original languageEnglish (US)
Pages (from-to)7838-7845
Number of pages8
JournalJournal of Immunology
Issue number12
StatePublished - Jun 15 2009
Externally publishedYes

ASJC Scopus subject areas

  • Immunology
  • Medicine(all)


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