title: Involvement of CD28 in MHC-unrestricted cytotoxicity mediated by a human natural killer leukemia cell line.
abstract: NK cells and certain CTL can recognize and lyse targets without restriction by the MHC. NK cells do not express CD3/TCR complexes and the membrane receptors participating in MHC-unrestricted cytotoxicity are largely unknown. We demonstrate that YT2C2, a human NK leukemia cell line, expresses the CD28 differentiation Ag and can spontaneously lyse both murine and human cell lines expressing B7, a B cell- activation Ag that is a ligand for CD28. The participation of CD28/B7 interactions in MHC-unrestricted cytotoxicity mediated by YT2C2 cells was demonstrated by correlation of target sensitivity with levels of B7 expression, inhibition of cytotoxicity by anti-CD28 or anti-B7 mAb, and by making both murine and human cell lines susceptible to YT2C2-mediated lysis by genetic transfection with expression vectors containing B7 cDNA. However, CD28/B7 interactions alone were insufficient to initiate cytotoxicity. mAb inhibition experiments and selection of CD54- (intercellular adhesion molecule-1) deficient B cell targets indicated that CD11a/18 (lymphocyte function-associated Ag-1) also cooperated in CD28/B7-dependent cytotoxicity. The requirement for both CD28/B7 and lymphocyte function-associated Ag-1/intercellular adhesion molecule-1 interactions in YT2C2-mediated MHC-unrestricted cytotoxicity was confirmed by demonstrating that efficient lysis of murine L cells required cotransfection with both B7 and intercellular adhesion molecule-1. These findings support the concept that MHC-unrestricted cytotoxicity may not be due to a unique receptor, but may result from interactions between an appropriate array of "adhesion" molecules with their ligands.
authors.affiliation: Department of Immunology, DNAX Research Institute for Cellular and Molecular Biology, Palo Alto, CA 94304.
authors.forename: M
authors.initials: M
authors.lastname: Azuma
authors.forename: M
authors.initials: M
authors.lastname: Cayabyab
authors.forename: D
authors.initials: D
authors.lastname: Buck
authors.forename: J H
authors.initials: JH
authors.lastname: Phillips
authors.forename: L L
authors.initials: LL
authors.lastname: Lanier
mesh_terms: D015703:Antigens, CD / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D000954:Antigens, Surface / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology; D018122:B7-1 Antigen; D018106:CD28 Antigens; D015815:Cell Adhesion Molecules / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D006801:Humans; D018799:Intercellular Adhesion Molecule-1; D007694:Killer Cells, Natural / Q000276:immunology*; D016169:Lymphocyte Function-Associated Antigen-1 / Q000276:immunology; D008285:Major Histocompatibility Complex; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D018122:B7-1 Antigen; D018106:CD28 Antigens; D015815:Cell Adhesion Molecules; D016169:Lymphocyte Function-Associated Antigen-1; D018799:Intercellular Adhesion Molecule-1