title: Localization of Fas ligand in cytoplasmic granules of CD8+ cytotoxic T lymphocytes and natural killer cells: participation of Fas ligand in granule exocytosis model of cytotoxicity.
abstract: Fas ligand (FasL) has been implicated in cytotoxic T lymphocyte (CTL)- and natural killer (NK) cell-mediated cytotoxicity. In the present study, we investigated the localization of FasL in murine CTL and NK cells. Immunocytochemical staining showed that FasL was stored in cytoplasmic granules of CD8+ CTL clones and in vivo activated CTL and NK cells, where perforin and granzyme A also resided. Immunoelectron microscopy revealed that FasL was localized on outer membrane of the cytoplasmic granules, while perforin was localized in internal vesicles. Western blot analysis showed that the membrane-type FasL of 40 kDa was stored in CD8+ CTL clones but not in CD4+ CTL clones. By utilizing a granule exocytosis inhibitor (TN16), we demonstrated that FasL translocated onto cell surface upon degranulation of anti-CD3-stimulated CD8+ CTL clones. Moreover, TN16 markedly inhibited the FasL-mediated cytotoxicity by CD8+ T cell clones and NK cells. These results suggested a substantial contribution of FasL to granule exocytosis-mediated target cell lysis by CD8+ CTL and NK cells.
authors.affiliation: Division of Pathology, Central Laboratory of Medical Sciences, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kojima
authors.forename: Akemi
authors.initials: A
authors.lastname: Kawasaki-Koyanagi
authors.forename: Noriyoshi
authors.initials: N
authors.lastname: Sueyoshi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kanai
authors.forename: Hideo
authors.initials: H
authors.lastname: Yagita
authors.forename: Ko
authors.initials: K
authors.lastname: Okumura
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D003594:Cytoplasmic Granules / Q000737:chemistry / Q000378:metabolism*; D003602:Cytotoxicity, Immunologic; D005089:Exocytosis; D053222:Fas Ligand Protein; D005434:Flow Cytometry; D006801:Humans; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D011760:Pyrrolidinones / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology / Q000378:metabolism*
chemical_list: D000954:Antigens, Surface; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D011760:Pyrrolidinones; D054353:Perforin; C038092:TN 16