title: CD8+CD28- T cells: certainties and uncertainties of a prevalent human T-cell subset.
abstract: Human peripheral blood CD8+ T cells comprise cells that are in different states of differentiation and under the control of complex homeostatic processes. In a number of situations ranging from chronic inflammatory conditions and infectious diseases to ageing, immunodeficiency, iron overload and heavy alcohol intake, major phenotypic changes, usually associated with an increase in CD8+ T cells lacking CD28 expression, take place. CD8+CD28- T cells are characterized by a low proliferative capacity to conventional stimulation in vitro and by morphological and functional features of activated/memory T cells. Although the nature of the signals that give origin to this T-cell subset is uncertain, growing evidence argues for the existence of an interplay between epithelial cells, molecules with the MHC-class I fold and CD8+ T cells. The possibility that the generation of CD8+CD28- T cells is the combination of TCR/CD3zeta- and regulatory factor-mediated signals as a result of the sensing of modifications of the internal environment is discussed.
authors.affiliation: Laboratory of Molecular Immunology, Institute for Molecular and Cell Biology (IBMC) and Molecular Immunology and Pathology, Abel Salazar Institute for the Biomedical Sciences(ICBAS), Porto, Portugal. farosa@ibmc.up.pt
authors.forename: Fernando A
authors.initials: FA
authors.lastname: Arosa
mesh_terms: D000818:Animals; D015415:Biomarkers; D018106:CD28 Antigens / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D015536:Down-Regulation; D004847:Epithelial Cells / Q000166:cytology / Q000276:immunology; D006304:Health Status; D006801:Humans; D016130:Immunophenotyping; D015398:Signal Transduction / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology
chemical_list: D015415:Biomarkers; D018106:CD28 Antigens