T cell activation determined by T cell receptor number and tunable thresholds.
The requirements for T cell activation have been reported to vary widely depending on the state of the T cell, the type of antigen-presenting cell, and the nature of the T cell receptor (TCR) ligand. A unitary requirement for T cell responses was revealed by measurement of the number of triggered TCRs. Irrespective of the nature of the triggering ligand, T cells "counted" the number of triggered TCRs and responded when a threshold of approximately 8000 TCRs was reached. The capacity to reach the activation threshold was severely compromised by a reduction in the number of TCRs. Costimulatory signals lowered the activation threshold to approximately 1500 TCRs, thus making T cells more sensitive to antigenic stimulation.
Viola
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Basel Institute for Immunology, Switzerland.
Lanzavecchia
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D000906:Antibodies / Q000276:immunology; D000938:Antigen-Presenting Cells / Q000276:immunology; D018122:B7-1 Antigen / Q000276:immunology; D001427:Bacterial Toxins; D017252:CD3 Complex / Q000276:immunology; D002460:Cell Line; D002999:Clone Cells; D015536:Down-Regulation; D004768:Enterotoxins / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D008213:Lymphocyte Activation; D010455:Peptides / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology; D018089:Superantigens / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D000906:Antibodies; D018122:B7-1 Antigen; D001427:Bacterial Toxins; D017252:CD3 Complex; D004768:Enterotoxins; D000949:Histocompatibility Antigens Class II; D010455:Peptides; D011948:Receptors, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; D018089:Superantigens; C030107:enterotoxin F, Staphylococcal; D007371:Interferon-gamma