Fas (CD95/APO-1) limits the expansion of T lymphocytes in an environment of limited T-cell antigen receptor/MHC contacts.
Int Immunol
; 23(2): 75-88, 2011 Feb.
Article
em En
| MEDLINE
| ID: mdl-21266499
ABSTRACT
Fas-deficient mice (Fas(lpr/lpr)) and humans have profoundly dysregulated T lymphocyte homeostasis, which manifests as an accumulation of CD4(+) and CD8(+) T cells as well as an unusual population of CD4(-)CD8(-)TCRαß(+) T cells. To date, no unifying model has explained both the increased T-cell numbers and the origin of the CD4(-)CD8(-)TCRαß(+) T cells. As Fas(lpr/lpr) mice raised in a germ-free environment still manifest lymphadenopathy, we considered that this process is primarily driven by recurrent low-avidity TCR signaling in response to self-peptide/MHC as occurs during homeostatic proliferation. In these studies, we developed two independent systems to decrease the number of self-peptide/MHC contacts. First, expression of MHC class I was reduced in OT-I TCR transgenic mice. Although OT-I Fas(lpr/lpr) mice did not develop lymphadenopathy characteristic of Fas(lpr/lpr) mice, in the absence of MHC class I, OT-I Fas(lpr/lpr) T cells accumulated as both CD8(+) and CD4(-)CD8(-) T cells. In the second system, re-expression of ß(2)m limited to thymic cortical epithelial cells of Fas(lpr/lpr) ß(2)m-deficient mice yielded a model in which polyclonal CD8(+) thymocytes entered a peripheral environment devoid of MHC class I. These mice accumulated significantly greater numbers of CD4(-)CD8(-)TCRαß(+) T cells than conventional Fas(lpr/lpr) mice. Thus, Fas shapes the peripheral T-cell repertoire by regulating the survival of a subset of T cells proliferating in response to limited self-peptide/MHC contacts.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Receptores de Antígenos de Linfócitos T
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Linfócitos T
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Antígenos de Histocompatibilidade Classe I
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Receptor fas
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Int Immunol
Assunto da revista:
ALERGIA E IMUNOLOGIA
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Estados Unidos