| Autor: |
Cummings LA; Department of Laboratory Medicine, University of Washington, Seattle, WA 98195, USA., Barrett SL, Wilkerson WD, Fellnerova I, Cookson BT |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of immunology (Baltimore, Md. : 1950) [J Immunol] 2005 Jun 15; Vol. 174 (12), pp. 7929-38. |
| DOI: |
10.4049/jimmunol.174.12.7929 |
| Abstrakt: |
Salmonella typhimurium, a facultatively intracellular pathogen, regulates expression of virulence factors in response to distinct environments encountered during the course of infection. We tested the hypothesis that the transition from extra- to intracellular environments during Salmonella infection triggers changes in Ag expression that impose both temporal and spatial limitations on the host T cell response. CD4(+) T cells recovered from Salmonella immune mice were propagated in vitro using Ag derived from bacteria grown in conditions designed to emulate extra- or intracellular environments in vivo. Extracellular phase bacteria supported a dominant T cell response to the flagellar subunit protein FliC, whereas intracellular phase bacteria were unable to support expansion of FliC-specific T cells from populations known to contain T cells with reactivity to this Ag. This result was attributed to bacterial regulation of FliC expression: transcription and protein levels were repressed in bacteria growing in the spleens of infected mice. Furthermore, Salmonella-infected splenocytes taken directly ex vivo stimulated FliC-specific T cell clones only when intracellular FliC expression was artificially up-regulated. Although it has been suggested that a microanatomical separation of immune T cells and infected APC exists in vivo, we demonstrate that intracellular Salmonella can repress FliC expression below the T cell activation threshold. This potentially provides a mechanism for intracellular Salmonella at systemic sites to avoid detection by Ag-specific T cells primed at intestinal sites early in infection. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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