Cross-linking of T-cell receptors on double-positive thymocytes induces a cytokine-mediated stromal activation process linked to cell death.
To investigate molecular events associated with the intrathymic process of negative selection, we established an in vivo system using an anti-CD3 epsilon monoclonal antibody to induce synchronous apoptosis in the thymus of AND T-cell receptor (TCR) transgenic RAG-2-/- mice in a non-selecting haplotype. This model eliminates endogenous negative selection as well as gene activation in the mature thymocyte compartment, offering an ideal source of tester (anti-CD3 epsilon-treated) and driver (untreated) thymus RNA for representational difference analysis (RDA). Fourteen mRNA sequences that are up-regulated in the thymuses of such mice 2-6 h after anti-CD3 epsilon treatment were identified. Surprisingly, the majority of these transcripts were derived from stromal cells rather than the TCR-cross-linked CD4+CD8+TCRlow thymocytes including the macrophage products IL-1, the chemokine Mig and the transcription factor LRG-21. IFN-gamma secretion from the CD4+CD8+TCRlow thymocytes regulates macrophage Mig production. Three other cytokines (IL-4, GM-CSF and TNF-alpha), known to activate a variety of stromal cells, are also induced in the same thymocyte population undergoing apoptosis. Expression of a TNF-alpha-inducible gene, B94, in stromal cells after TCR ligation further supports the notion of cross-talk between thymocytes and stroma. Thus, TCR-triggered immature thymocytes elaborate cytokines which may regulate the delivery of further signals from stromal cells required for apoptosis.
Lerner
A
A
Laboratory of Immunobiology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
Clayton
L K
LK
Mizoguchi
E
E
Ghendler
Y
Y
van Ewijk
W
W
Koyasu
S
S
Bhan
A K
AK
Reinherz
E L
EL
D000818:Animals; D000911:Antibodies, Monoclonal; D017209:Apoptosis / Q000276:immunology; D001483:Base Sequence; D017252:CD3 Complex; D003001:Cloning, Molecular; D003432:Cross-Linking Reagents; D016207:Cytokines / Q000096:biosynthesis; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology; D015533:Transcriptional Activation
D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D003432:Cross-Linking Reagents; D016207:Cytokines; D017931:DNA Primers; D018076:DNA, Complementary; D011948:Receptors, Antigen, T-Cell