title: LFA-1 contributes an early signal for NK cell cytotoxicity.
abstract: Cytotoxicity of human NK cells is activated by receptors that bind ligands on target cells, but the relative contribution of the many different activating and inhibitory NK cell receptors is difficult to assess. In this study, we describe an experimental system that circumvents some of the difficulties. Adhesion through beta2 integrin LFA-1 is a common requirement of CTLs and NK cells for efficient lysis of target cells. However, the contribution of LFA-1 to activation signals for NK cell cytotoxicity, besides its role in adhesion, is unclear. The role of LFA-1 was evaluated by exposing NK cells to human ICAM-1 that was either expressed on a Drosophila insect cell line, or directly coupled to beads. Expression of ICAM-1 on insect cells was sufficient to induce lysis by NK cells through LFA-1. Coexpression of peptide-loaded HLA-C with ICAM-1 on insect cells blocked the LFA-1-dependent cytotoxicity of NK cells that expressed HLA-C-specific inhibitory receptors. Polarization of cytotoxic granules in NK cells toward ICAM-1- and ICAM-2-coated beads showed that engagement of LFA-1 alone is sufficient to initiate activation signals in NK cells. Thus, in contrast to T cells, in which even adhesion through LFA-1 is dependent on signals from other receptors, NK cells receive early activation signals directly through LFA-1.
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
authors.forename: Domingo F
authors.initials: DF
authors.lastname: Barber
authors.forename: Mathias
authors.initials: M
authors.lastname: Faure
authors.forename: Eric O
authors.initials: EO
authors.lastname: Long
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000276:immunology; D016923:Cell Death / Q000276:immunology; D002460:Cell Line; D002999:Clone Cells; D003594:Cytoplasmic Granules / Q000378:metabolism; D003601:Cytotoxicity Tests, Immunologic / Q000379:methods; D003602:Cytotoxicity, Immunologic / Q000235:genetics; D004330:Drosophila / Q000166:cytology / Q000235:genetics; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000276:immunology; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D020033:Protein Isoforms / Q000502:physiology / Q000633:toxicity; D011971:Receptors, Immunologic / Q000502:physiology; D054340:Receptors, KIR; D015398:Signal Transduction / Q000276:immunology*; D014162:Transfection
chemical_list: D016169:Lymphocyte Function-Associated Antigen-1; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D020033:Protein Isoforms; D011971:Receptors, Immunologic; D054340:Receptors, KIR; D054353:Perforin; D018799:Intercellular Adhesion Molecule-1