title: CD11b expression identifies CD8+CD28+ T lymphocytes with phenotype and function of both naive/memory and effector cells.
abstract: A previously unreported CD8(+)CD28(+)CD11b(+) T cell subset occurs in healthy individuals and expands in patients suffering from primary viral infections. In functional terms, these cells share the features of naive/memory CD8(+)CD28(+)CD11b(-) and terminally differentiated effector CD8(+)CD28(-)CD11b(+) subpopulations. Like CD28(-) cells, CD28(+)CD11b(+) lymphocytes have the ability to produce IFN-gamma, to express perforin granules in vivo, and to exert a potent cytolytic activity. Moreover, these cells can respond to chemotactic stimuli and can efficiently cross the endothelial barrier. In contrast, like their CD11b(-) counterpart, they still produce IL-2 and retain the ability to proliferate following mitogenic stimuli. The same CD28(+)CD11b(+) subpopulation detected in vivo could be generated by culturing naive CD28(+)CD11b(-) cells in the presence of mitogenic stimuli following the acquisition of a CD45RO(+) memory phenotype. Considering both phenotypic and functional properties, we argue that this subset may therefore constitute an intermediate phenotype in the process of CD8(+) T cell differentiation and that the CD11b marker expression can distinguish between memory- and effector-type T cells in the human CD8(+)CD28(+) T cell subset.
authors.affiliation: Institute of Microbiology and Department of Infectious Diseases, University of Brescia Medical School, Brescia, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Fiorentini
authors.forename: S
authors.initials: S
authors.lastname: Licenziati
authors.forename: G
authors.initials: G
authors.lastname: Alessandri
authors.forename: F
authors.initials: F
authors.lastname: Castelli
authors.forename: S
authors.initials: S
authors.lastname: Caligaris
authors.forename: M
authors.initials: M
authors.lastname: Bonafede
authors.forename: M
authors.initials: M
authors.lastname: Grassi
authors.forename: E
authors.initials: E
authors.lastname: Garrafa
authors.forename: A
authors.initials: A
authors.lastname: Balsari
authors.forename: A
authors.initials: A
authors.lastname: Turano
authors.forename: A
authors.initials: A
authors.lastname: Caruso
mesh_terms: D018106:CD28 Antigens / Q000096:biosynthesis* / Q000276:immunology; D016827:CD8 Antigens / Q000096:biosynthesis* / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D002448:Cell Adhesion / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology; D002460:Cell Line; D002465:Cell Movement / Q000276:immunology; D002634:Chemotaxis, Leukocyte / Q000276:immunology; D002644:Chickenpox / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis; D003602:Cytotoxicity, Immunologic; D004730:Endothelium, Vascular / Q000166:cytology / Q000276:immunology; D006801:Humans; D007156:Immunologic Memory; D016130:Immunophenotyping; D007244:Infectious Mononucleosis / Q000276:immunology; D007376:Interleukin-2 / Q000494:pharmacology; D007399:Interphase / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D016177:Macrophage-1 Antigen / Q000096:biosynthesis* / Q000276:immunology; D008457:Measles / Q000276:immunology; D008562:Membrane Glycoproteins / Q000096:biosynthesis; D054353:Perforin; D010835:Phytohemagglutinins / Q000494:pharmacology; D052899:Pore Forming Cytotoxic Proteins; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism*
chemical_list: D018106:CD28 Antigens; D016827:CD8 Antigens; D016207:Cytokines; D007376:Interleukin-2; D016177:Macrophage-1 Antigen; D008562:Membrane Glycoproteins; D010835:Phytohemagglutinins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin