title: Influence of the T cell receptor alpha-chain on T cell reactivity and tolerance to Mls-1 in T cell receptor beta-chain transgenic mice.
abstract: Previous analyses of a TCR V beta 8.1 transgenic mouse revealed multiple mechanisms of tolerance to the retroviral superantigen, Mls-1. Whereas some T cells were clonally deleted in the thymus, others became anergic in the periphery, or remained unaffected by the expression of Mls-1. In addition, a strong correlation between TCR alpha-chain usage and Mls-1 reactivity of individual transgenic V beta 8.1+ T cell hybridomas was established. Based on these observations, we speculated that the different mechanisms of tolerance were a consequence of the alpha-chain-mediated differences in Mls-1 reactivity. In the current studies, we make use of a V alpha 2-specific mAb to directly examine the role of the alpha-chain on tolerance in this transgenic model. We show, first, that V alpha 2+ CD4+ T cells, as a group, are relatively less Mls-1-reactive, and are elevated twofold in the periphery of Mls-1+ compared with Mls-1-V beta 8.1 transgenic mice. This elevated expression is also seen in the V alpha 2+ CD4+ population of mature thymocytes, but not in immature thymocytes. Second, Mls-1-induced neonatal tolerance in Mls-1-negative mice caused an increase of V alpha 2+ CD4+ T cells, comparable with the frequency of expression in transgenic mice that endogenously expressed Mls-1. Third, we have demonstrated a general correlation between the age-dependent increase in Mls-1-expression and the levels of V alpha 2+ CD4+ T cells during the first 4 wk of life. Taken together, these data suggest that the over-expression of V alpha 2+ CD4+ T cells in Mls-1+ mice is a consequence of mechanisms of tolerance, predominantly mediated by preferential lack of clonal deletion in the thymus. These data support the idea that clonal deletion is a competitive process and the influence of the TCR alpha-chain on the strength of Mls-1 reactivity of individual V beta 8.1+ transgenic T cells controls their susceptibility to clonal deletion.
authors.affiliation: Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105.
authors.forename: M A
authors.initials: MA
authors.lastname: Blackman
authors.forename: H P
authors.initials: HP
authors.lastname: Smith
authors.forename: P
authors.initials: P
authors.lastname: Le
authors.forename: D L
authors.initials: DL
authors.lastname: Woodland
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000276:immunology; D016516:CD4-CD8 Ratio; D007108:Immune Tolerance; D051379:Mice; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D016747:Minor Lymphocyte Stimulatory Antigens / Q000032:analysis / Q000276:immunology*; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000502:physiology*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D016747:Minor Lymphocyte Stimulatory Antigens; D016693:Receptors, Antigen, T-Cell, alpha-beta