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Immunology. 2011 Dec;134(4):487-97. doi: 10.1111/j.1365-2567.2011.03510.x.

Selective culling of high avidity antigen-specific CD4+ T cells after virulent Salmonella infection.

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1
Department of Pediatrics, University of Minnesota School of Medicine, Center for Microbiology and Infectious Disease Translational Research, Minneapolis, MN 55455, USA.

Abstract

Typhoid fever is a persistent infection caused by host-adapted Salmonella strains adept at circumventing immune-mediated host defences. Given the importance of T cells in protection, the culling of activated CD4+ T cells after primary infection has been proposed as a potential immune evasion strategy used by this pathogen. We demonstrate that the purging of activated antigen-specific CD4+ T cells after virulent Salmonella infection requires SPI-2 encoded virulence determinants, and is not restricted only to cells with specificity to Salmonella-expressed antigens, but extends to CD4+ T cells primed to expand by co-infection with recombinant Listeria monocytogenes. Unexpectedly, however, the loss of activated CD4+ T cells during Salmonella infection demonstrated using a monoclonal population of adoptively transferred CD4+ T cells was not reproduced among the endogenous repertoire of antigen-specific CD4+ T cells identified with MHC class II tetramer. Analysis of T-cell receptor variable segment usage revealed the selective loss and reciprocal enrichment of defined CD4+ T-cell subsets after Salmonella co-infection that is associated with the purging of antigen-specific cells with the highest intensity of tetramer staining. Hence, virulent Salmonella triggers the selective culling of high avidity activated CD4+ T-cell subsets, which re-shapes the repertoire of antigen-specific T cells that persist later after infection.

PMID:
22044420
PMCID:
PMC3230801
DOI:
10.1111/j.1365-2567.2011.03510.x
[Indexed for MEDLINE]
Free PMC Article
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