Antigen, in the presence of TGF-beta, induces up-regulation of FoxP3gfp+ in CD4+ TCR transgenic T cells that mediate linked suppression of CD8+ T cell responses.
CD4(+)CD25(+) regulatory T cells (Tregs) inhibit immune responses to a variety of Ags, but their specificity and mechanism of suppression are controversial. This controversy is largely because many studies focused on natural Tregs with undefined specificities and suppression has frequently been measured on polyclonal T cell responses. To address the issue of specificity further, we have bred K(d)-specific, CD4(+) TCR (TCR75) transgenic mice to Foxp3(gfp) knockin reporter mice to permit sorting of Tregs with a known specificity. Foxp3(gfp).TCR75 mice did not express significant numbers of natural FoxP3(+) Tregs expressing the TCR75 transgenes, but FoxP3 expression was induced by stimulating with K(d) plus TGF-beta. The resulting GFP(+) TCR75 cells were anergic, whereas the GFP(-) TCR75 cells proliferated upon restimulation with K(d) peptide. Yet both exhibited severely reduced expression of intracellular IFN-gamma and TNF-alpha upon restimulation. GFP(+), but not GFP(-), TCR75 T cells suppressed responses by naive TCR75 T cells and by nontransgenic spleen cells stimulated with anti-CD3. GFP(+) TCR75 cells also inhibited polyclonal C57BL/6 anti-K(d) CTL responses if the APC expressed K(d) and both MHC class I and class II, and responses by OT1 T cells to B6.K(d).OVA but not B6.K(d) plus OVA expressing APC, demonstrating linked-suppression of CD8 responses. Thus, Tregs exhibit a greater degree of specificity in vitro than previously appreciated. The observation that Tregs and responder T cells must recognize the same APC provides a mechanistic explanation for the observation that Tregs must be in direct contact with effector T cells to suppress their responses.
Department of Ophthalmology, University of Alabama AL 35233-7331, USA. jkapp@uab.edu
Judith A
JA
Kapp
Kazuhito
K
Honjo
Linda M
LM
Kapp
Kelly
K
Goldsmith
R Pat
RP
Bucy
D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D000938:Antigen-Presenting Cells / Q000276:immunology; D000941:Antigens / Q000235:genetics / Q000276:immunology*; D017252:CD3 Complex / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D049109:Cell Proliferation; D017635:Clonal Anergy / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000276:immunology*; D017930:Genes, Reporter / Q000235:genetics / Q000276:immunology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D007108:Immune Tolerance / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D007371:Interferon-gamma / Q000276:immunology; D051379:Mice; D008822:Mice, Transgenic; D010455:Peptides / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*; D016212:Transforming Growth Factor beta / Q000276:immunology*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics / Q000276:immunology*
D000906:Antibodies; D000941:Antigens; D017252:CD3 Complex; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D010455:Peptides; D011948:Receptors, Antigen, T-Cell; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D049452:Green Fluorescent Proteins; D007371:Interferon-gamma