title: Serpin-6 expression protects embryonic stem cells from lysis by antigen-specific CTL.
abstract: The immune response to embryonic stem (ES) cells is still poorly understood. In this study, we addressed the adaptive cellular immune response to undifferentiated and differentiated ES cells infected with lymphocytic choriomeningitis virus (LCMV), a vertically transmitted pathogen in mice and humans. In contrast to the prevailing view, we found that undifferentiated and differentiated murine ES cells express MHC class I molecules, although at low levels. When cocultured with LCMV-infected ES cells, syngeneic but not allogeneic LCMV-specific CTL secrete IFN-gamma. Strikingly, LCMV-specific CTL do not efficiently kill LCMV-infected ES cells. ES cells showed high-level expression of the serine protease inhibitor 6, an endogenous inhibitor of the CTL-derived cytotoxic effector molecule granzyme B. Down-regulation of serpin-6 by RNA interference sensitized ES cells for CTL-induced cell death. The results of this study suggest that LCMV-infected murine ES cells present viral Ags and are recognized by LCMV-specific CTL in a MHC class I-restricted manner, yet resist CTL-mediated lysis through high-level expression of serine protease inhibitor 6.
authors.affiliation: Institute for Medical Microbiology, Immunology and Hygiene, Medical Center, University of Cologne, Goldenfelsstrasse 19-21, 50935 Cologne, Germany.
authors.forename: Zeinab
authors.initials: Z
authors.lastname: Abdullah
authors.forename: Tomo
authors.initials: T
authors.lastname: Saric
authors.forename: Hamid
authors.initials: H
authors.lastname: Kashkar
authors.forename: Nikola
authors.initials: N
authors.lastname: Baschuk
authors.forename: Benjamin
authors.initials: B
authors.lastname: Yazdanpanah
authors.forename: Bernd K
authors.initials: BK
authors.lastname: Fleischmann
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hescheler
authors.forename: Martin
authors.initials: M
authors.lastname: Krönke
authors.forename: Olaf
authors.initials: O
authors.lastname: Utermöhlen
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D000956:Antigens, Viral / Q000276:immunology* / Q000378:metabolism; D002460:Cell Line; D018920:Coculture Techniques; D053595:Embryonic Stem Cells / Q000276:immunology* / Q000378:metabolism / Q000821:virology; D005786:Gene Expression Regulation / Q000276:immunology*; D053804:Granzymes / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D008216:Lymphocytic Choriomeningitis / Q000276:immunology / Q000378:metabolism; D008217:Lymphocytic choriomeningitis virus / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D015842:Serine Proteinase Inhibitors / Q000276:immunology / Q000378:metabolism; D015843:Serpins / Q000096:biosynthesis* / Q000276:immunology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000378:metabolism
chemical_list: D000956:Antigens, Viral; D015395:Histocompatibility Antigens Class I; D015842:Serine Proteinase Inhibitors; D015843:Serpins; D007371:Interferon-gamma; D053804:Granzymes; C509214:Gzmb protein, mouse