title: Effects of Chlamydia trachomatis infection on the expression of natural killer (NK) cell ligands and susceptibility to NK cell lysis.
abstract: Natural killer (NK) cells are an important component of the immediate immune response to infections, including infection by intracellular bacteria. We have investigated recognition of Chlamydia trachomatis (CT) by NK cells and show that these cells are activated to produce interferon (IFN)-gamma when peripheral blood mononuclear cells (PBMC) are stimulated with CT organisms. Furthermore, infection of epithelial cell lines with CT renders them susceptible to lysis by human NK cells. Susceptibility was observed 18-24 h following infection and required protein synthesis by the infecting chlamydiae, but not by the host cell; heat or UV inactivated chlamydiae did not induce susceptibility to NK cell lysis. CT infection was also shown to decrease the expression of classical and non-classical major histocompatibility complex (MHC) molecules on infected cells, thus allowing recognition by NK cells when combined with an activating signal. A candidate activating signal is MICA/B, which was shown to be expressed constitutively on epithelial cells.
authors.affiliation: Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge UK.
authors.forename: C E
authors.initials: CE
authors.lastname: Hook
authors.forename: N
authors.initials: N
authors.lastname: Telyatnikova
authors.forename: J C
authors.initials: JC
authors.lastname: Goodall
authors.forename: V M
authors.initials: VM
authors.lastname: Braud
authors.forename: A J
authors.initials: AJ
authors.lastname: Carmichael
authors.forename: M R
authors.initials: MR
authors.lastname: Wills
authors.forename: J S H
authors.initials: JS
authors.lastname: Gaston
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis; D002460:Cell Line; D002690:Chlamydia Infections / Q000276:immunology*; D002692:Chlamydia trachomatis / Q000276:immunology*; D004847:Epithelial Cells / Q000276:immunology; D006367:HeLa Cells; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008024:Ligands; D008285:Major Histocompatibility Complex / Q000276:immunology; D011971:Receptors, Immunologic / Q000276:immunology
chemical_list: D001426:Bacterial Proteins; D008024:Ligands; D011971:Receptors, Immunologic; D007371:Interferon-gamma