Selection and behavior of CD4+ CD25+ T cells in vivo: lessons from T cell receptor transgenic models.
Despite great interest in CD4+ CD25+ suppressor T cells, many of the fundamental properties of these cells remain enigmatic. This is in part due to experimental limitations inherent to the study of polyclonal suppressor T cells, and the extensive use of in vitro assays. This review article intends to outline recent advances in our understanding of the biology of suppressor T cells that have emerged from the analysis of T cell receptor (TCR) transgenic models. Several laboratories have taken advantage of model systems in which suppressor T cells of defined antigen-specificity are naturally selected in order to characterize the selection and behavior of these cells in vivo. In addition to providing valuable insights into the mechanism of differentiation of suppressor T cells, these systems now offer new possibilities for understanding the mode of action of suppressor T cells. For example, adoptive transfer of small numbers of ex vivo isolated TCR transgenic suppressor T cells allows for the visualization of the fate of such cells when confronted with cognate antigen in a quasi-normal, nonlymphopenic environment. Characteristic features of the currently available TCR transgenic models of suppressor T cells will be highlighted, and particular issues pertaining to the differentiation, function, and homeostasis of this T cell subset that have emerged from these models will be discussed.
Research Institute of Molecular Pathology, Dr. Bohr-Gasse 7, 1030 Vienna, Austria. klein@imp.univie.ac.at
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Klein
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Emmerich
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d'Cruz
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Aschenbrenner
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Khazaie
D000818:Animals; D030801:Animals, Genetically Modified; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D017635:Clonal Anergy; D006801:Humans; D038041:Lymphopoiesis; D011948:Receptors, Antigen, T-Cell / Q000235:genetics; D015375:Receptors, Interleukin-2 / Q000276:immunology*; D037182:T-Cell Antigen Receptor Specificity / Q000235:genetics; D016176:T-Lymphocyte Subsets / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology
D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2