TY - JOUR
T1 - Mutually antagonistic signals regulate selection of the T cell repertoire
AU - Stephens, Geoffrey L.
AU - Ashwell, Jonathan D.
AU - Ignatowicz, Leszek
N1 - Funding Information:
1Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta, GA 30912-2600, USA 2Laboratory of Immune Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
PY - 2003/5/1
Y1 - 2003/5/1
N2 - The sensitivity of T cells to agonist-induced death during development contrasts with their proliferative responses after agonist challenge in the periphery. The means by which TCR engagement results in these distinct outcomes is incompletely understood. It has been previously hypothesized that glucocorticoids (GC) modulate the threshold for thymocyte activation by blunting the consequences of TCR engagement. In support of this possibility, inhibition of GC production in fetal thymic organ culture was shown to result in CD4+CD8+ thymocyte apoptosis. This was dependent upon MHC diversity, implying that endogenous GC might regulate antigen-specific selection. Similarly, mice expressing reduced GC receptor (GR) levels due to the presence of an antisense transgene have fewer CD4+CD8+ thymocytes, which was due to an impaired transition from CD4-CD8- precursors and increased apoptosis. Here we ask how manipulating peptide diversity in the context of reduced GC signaling might affect T cell development and function. In mice with impaired GR expression there was a rescue of thymocyte cellularity and proportions as the diversity of peptides presented by self-MHC was reduced. Furthermore, whereas more CD4+ T cells survived the selection process in mice expressing single-peptide-MHC class II complexes and reduced GR levels, these cells largely failed to recognize the same MHC molecules bound with foreign peptides. Together, these results support a role for endogenous GC in balancing TCR-mediated signals during thymic selection.
AB - The sensitivity of T cells to agonist-induced death during development contrasts with their proliferative responses after agonist challenge in the periphery. The means by which TCR engagement results in these distinct outcomes is incompletely understood. It has been previously hypothesized that glucocorticoids (GC) modulate the threshold for thymocyte activation by blunting the consequences of TCR engagement. In support of this possibility, inhibition of GC production in fetal thymic organ culture was shown to result in CD4+CD8+ thymocyte apoptosis. This was dependent upon MHC diversity, implying that endogenous GC might regulate antigen-specific selection. Similarly, mice expressing reduced GC receptor (GR) levels due to the presence of an antisense transgene have fewer CD4+CD8+ thymocytes, which was due to an impaired transition from CD4-CD8- precursors and increased apoptosis. Here we ask how manipulating peptide diversity in the context of reduced GC signaling might affect T cell development and function. In mice with impaired GR expression there was a rescue of thymocyte cellularity and proportions as the diversity of peptides presented by self-MHC was reduced. Furthermore, whereas more CD4+ T cells survived the selection process in mice expressing single-peptide-MHC class II complexes and reduced GR levels, these cells largely failed to recognize the same MHC molecules bound with foreign peptides. Together, these results support a role for endogenous GC in balancing TCR-mediated signals during thymic selection.
KW - Knockout
KW - Lymphocyte development
KW - T lymphocyte
KW - Thymus
KW - Transgenic
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U2 - 10.1093/intimm/dxg060
DO - 10.1093/intimm/dxg060
M3 - Article
C2 - 12697662
AN - SCOPUS:0242417043
SN - 0953-8178
VL - 15
SP - 623
EP - 632
JO - International Immunology
JF - International Immunology
IS - 5
ER -