title: B7x: a widely expressed B7 family member that inhibits T cell activation.
abstract: B7 family proteins provide costimulatory signals that regulate T cell responses. Here we report the third set of B7 family-related T cell inhibitory molecules with the identification of a homolog of the B7 family, B7x. It is expressed in immune cells, nonlymphoid tissues, and some tumor cell lines. B7x inhibits cell-cycle progression, proliferation, and cytokine production of both CD4+ and CD8+ T cells. B7x binds a receptor that is expressed on activated, but not resting T cells that is distinct from known CD28 family members. Its receptor may be a recently identified inhibitory molecule, B and T lymphocyte attenuator. These studies identify a costimulatory pathway that may have a unique function in downregulation of tissue-specific autoimmunity and antitumor responses.
authors.affiliation: Howard Hughes Medical Institute, Department of Molecular and Cell Biology, Cancer Research Laboratory, University of California, Berkeley, CA 94720, USA.
authors.forename: Xingxing
authors.initials: X
authors.lastname: Zang
authors.forename: P'ng
authors.initials: P
authors.lastname: Loke
authors.forename: Jayon
authors.initials: J
authors.lastname: Kim
authors.forename: Kenneth
authors.initials: K
authors.lastname: Murphy
authors.forename: Rebecca
authors.initials: R
authors.lastname: Waitz
authors.forename: James P
authors.initials: JP
authors.lastname: Allison
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD; D018122:B7-1 Antigen / Q000502:physiology*; D060890:B7-H1 Antigen; D001798:Blood Proteins / Q000502:physiology; D018106:CD28 Antigens / Q000502:physiology; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D015536:Down-Regulation; D006801:Humans; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010455:Peptides / Q000502:physiology; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D015703:Antigens, CD; D018122:B7-1 Antigen; D060890:B7-H1 Antigen; D001798:Blood Proteins; C423236:CD274 protein, human; D018106:CD28 Antigens; C498919:Cd274 protein, mouse; D008562:Membrane Glycoproteins; D010455:Peptides; D011948:Receptors, Antigen, T-Cell