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J. Exp. Med.,
Volume 189, Number 2, January 18, 1999 231-239
1 Inhibits Fas Ligand
Expression and Subsequent Activation-induced Cell Death
in T Cells via Downregulation of c-Myc
By
From the Division of Cellular Immunology, La Jolla Institute for Allergy and Immunology, San Diego,
California 92121
Activation-induced cell death (AICD) is a process that regulates the size and the duration of the
primary immune T cell response. In this report, we investigated the mechanisms involved in
the regulation of AICD by transforming growth factor
1 (TGF-
1). We found that TGF-
1
decreased apoptosis of human T cells or T cell hybridomas after activation by anti-CD3. This
decrease was associated with inhibition of Fas (Apo-1/CD95) ligand (FasL) expression, whereas
Fas signaling was not affected by TGF-
1. In parallel, TGF-
1 inhibited c-Myc expression in
T cell hybridomas, and ectopic expression of a chimeric molecule composed of c-Myc and the
steroid binding domain of the estrogen receptor (Myc-ER) blocked both the inhibition of FasL
and the decrease of AICD induced by TGF-
1, providing that 4-hydroxytamoxifen was
present. These results identify one mechanism by which TGF-
1 blocks AICD to allow the
clonal expansion of effector T cells and the generation of memory T cells during immune responses.
;
Fas ligand;
c-myc
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