title: Mechanisms, manifestations, and failures of self-tolerance.
abstract: We have developed transgenic (Tg) mice that express the influenza virus A/PR/8/34 hemagglutinin (PR8 HA) as a well-characterized model antigen with which to analyze factors governing tolerance and autoreactivity among CD4+ T and B cells. To analyze how the expression of self-antigens in varying amounts and in different cell types and tissues affects these processes, we have used a variety of promoters and enhancers to drive HA expression. By mating these HA Tg mice with Tg mice-expressing HA-specific major histocompatibility complex (MHC) class II-restricted T cell receptors (TCRs), we have shown that variations in the expression of the HA in different HA Tg lineages can cause CD4+ T cells with identical specificity for a self-peptide either to be deleted (to varying degrees) or to undergo selection to become CD4+ CD25+ regulatory T cells. In addition, a high intrinsic affinity of the TCR for a self-peptide appears to be required for thymocytes to undergo selection to become CD4+ CD25+ regulatory T cells. We have also shown that separate populations of HA-specific B cells that participate at distinct phases of the immune response to the HA in BALB/c mice differ significantly in their sensitivity to negative selection by the neo-self HA. Together, these studies demonstrate that both the diversity of the CD4+ T cell and B cell responses to the HA and variations in the expression of the HA in HA Tg mice can significantly affect the mechanisms and extent of CD4+ T and B cell tolerance induction.
authors.affiliation: The Wistar Institute, Philadelphia, PA 19104, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Caton
mesh_terms: D000818:Animals; D015551:Autoimmunity / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D000939:Epitopes / Q000276:immunology; D006388:Hemagglutinins / Q000276:immunology; D051379:Mice; D008822:Mice, Transgenic; D017634:Self Tolerance / Q000276:immunology*
chemical_list: D000939:Epitopes; D006388:Hemagglutinins