title: Adaptive tolerance of CD4+ T cells in vivo: multiple thresholds in response to a constant level of antigen presentation.
abstract: The in vivo T cell response to persistent Ag contains a hyporesponsive phase following an initial expansion and subsequent partial deletion of the responding cells. The mechanism(s) responsible for this tolerance process is poorly understood. In this study, we describe a new paired transgenic model (TCR and Ag), which within 7-14 days produces 20-40 million hyporesponsive T cells. This state is characterized by an 85-95% reduction in all cytokine production, an impairment of re-expression of CD25 and CD69, and a desensitization of the proliferative response to Ag. TCR levels were normal, and in vivo mixing experiments showed no evidence for active suppression. The hyporesponsiveness partially dissipated without proliferation when the cells were transferred into a non-Ag-bearing host. If the second host expressed Ag, the T cells initially regained responsiveness, but then slowly entered an even deeper state of tolerance characterized by an additional 7- to 10-fold lowering of cytokine production and a greater desensitization of proliferation. Surprisingly, this readaptation took place with the same level of Ag presentation, suggesting that other parameters can influence the tolerance threshold. Both the readjustment in sensitivity and the reversal without Ag convincingly demonstrate for the first time a truly adaptive tolerance process in CD4+ T cells in vivo.
authors.affiliation: Laboratory of Cellular and Molecular Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: C
authors.initials: C
authors.lastname: Tanchot
authors.forename: D L
authors.initials: DL
authors.lastname: Barber
authors.forename: L
authors.initials: L
authors.lastname: Chiodetti
authors.forename: R H
authors.initials: RH
authors.lastname: Schwartz
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics / Q000276:immunology; D019264:Adoptive Transfer / Q000379:methods; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D000938:Antigen-Presenting Cells / Q000276:immunology; D017252:CD3 Complex / Q000096:biosynthesis / Q000235:genetics; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000637:transplantation*; D010856:Columbidae; D003574:Cytochrome c Group / Q000235:genetics / Q000276:immunology; D004306:Dose-Response Relationship, Immunologic; D007108:Immune Tolerance / Q000235:genetics; D007399:Interphase / Q000235:genetics / Q000276:immunology; D008213:Lymphocyte Activation / Q000235:genetics; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics
chemical_list: D017252:CD3 Complex; D003574:Cytochrome c Group; D016693:Receptors, Antigen, T-Cell, alpha-beta