title: A novel 80-kD cell surface structure identifies human circulating lymphocytes with natural killer activity.
abstract: Human lymphocytes with natural killer (NK) activity, including most activated gamma/delta+ T lymphocytes, recognize and lyse tumor target cells without requiring recognition of major histocompatibility complex antigen. However, unlike gamma/delta+ T lymphocytes, NK cells do not express CD3/T cell receptor (TCR) molecules, and the receptors involved in cell-mediated cytotoxicity are unknown. To further delineate circulating NK cells, we developed monoclonal antibodies (mAbs) against the human NK leukemia YT2C2. We report the isolation of a mAb termed BY55, recognizing at the cell surface a novel 80-kD protein with restricted expression. In addition to the immunizing cell line, this mAb binds to circulating NK cells, gamma/delta+ cells, and a minor subset of alpha/beta+ T lymphocytes. Expression of the BY55 mAb-reactive epitope/molecule is regulated by activation, as short-term culture of peripheral blood lymphocytes (PBL) with phorbol ester induced its downmodulation. Furthermore, BY55 mAb reactivity was found neither with the NK nor with the TCR alpha/beta+ gamma/delta+ clones tested. Biochemical studies as well as phenotypic analysis revealed that this structure is different from all previously identified molecules on the lymphocyte cell surface. Interestingly, we found that BY55+ cells exert most NK activity obtained with fresh circulating lymphocytes. We report that within fresh E rosette-positive PBL only a subset of the CD16+, CD56+, and CD57+ cells coexpressed BY55 molecule, indicating that BY55 mAb defines a unique subset mediating NK activity of circulating PBL.
authors.affiliation: Laboratoire INSERM U93, Association Claude Bernard, Hopital Saint-Louis, Paris, France.
authors.forename: H
authors.initials: H
authors.lastname: Maïza
authors.forename: G
authors.initials: G
authors.lastname: Leca
authors.forename: I G
authors.initials: IG
authors.lastname: Mansur
authors.forename: V
authors.initials: V
authors.lastname: Schiavon
authors.forename: L
authors.initials: L
authors.lastname: Boumsell
authors.forename: A
authors.initials: A
authors.lastname: Bensussan
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000032:analysis; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis; D000954:Antigens, Surface / Q000032:analysis* / Q000737:chemistry; D018801:CD2 Antigens; D019002:CD56 Antigen; D003602:Cytotoxicity, Immunologic; D006801:Humans; D007111:Immunity, Cellular; D007694:Killer Cells, Natural / Q000276:immunology*; D008213:Lymphocyte Activation; D016131:Lymphocyte Subsets / Q000276:immunology*; D008970:Molecular Weight; D017452:Receptors, IgG / Q000032:analysis; D011971:Receptors, Immunologic / Q000032:analysis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D018801:CD2 Antigens; D019002:CD56 Antigen; D017452:Receptors, IgG; D011971:Receptors, Immunologic; D013755:Tetradecanoylphorbol Acetate