title: Immunoselection by natural killer cells of PIGA mutant cells missing stress-inducible ULBP.
abstract: The mechanism by which paroxysmal nocturnal hemoglobinuria (PNH) clones expand is unknown. PNH clones harbor PIGA mutations and do not synthesize glycosylphosphatidylinositol (GPI), resulting in deficiency of GPI-linked membrane proteins. GPI-deficient blood cells often expand in patients with aplastic anemia who sustain immune-mediated marrow injury putatively induced by cytotoxic cells, hence suggesting that the injury allows PNH clones to expand selectively. We previously reported that leukemic K562 cells preferentially survived natural killer (NK) cell-mediated cytotoxicity in vitro when they acquired PIGA mutations. We herein show that the survival is ascribable to the deficiency of stress-inducible GPI-linked membrane proteins ULBP1 and ULBP2, which activate NK and T cells. The ULBPs were detected on GPI-expressing but not on GPI-deficient K562 cells. In the presence of antibodies to either the ULBPs or their receptor NKG2D on NK cells, GPI-expressing cells were as less NK sensitive as GPI-deficient cells. NK cells therefore spared ULBP-deficient cells in vitro. The ULBPs were identified only on GPI-expressing blood cells of a proportion of patients with PNH but none of healthy individuals. Granulocytes of the patients partly underwent killing by autologous cytotoxic cells, implying ULBP-associated blood cell injury. In this setting, the lack of ULBPs may allow immunoselection of PNH clones.
authors.affiliation: Department of Hematology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan.
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Hanaoka
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kawaguchi
authors.forename: Kentaro
authors.initials: K
authors.lastname: Horikawa
authors.forename: Shoichi
authors.initials: S
authors.lastname: Nagakura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Mitsuya
authors.forename: Hideki
authors.initials: H
authors.lastname: Nakakuma
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000741:Anemia, Aplastic / Q000150:complications / Q000235:genetics / Q000276:immunology; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology*; D004912:Erythrocytes / Q000276:immunology; D005260:Female; D058851:GPI-Linked Proteins; D017261:Glycosylphosphatidylinositols / Q000096:biosynthesis / Q000172:deficiency / Q000276:immunology; D006098:Granulocytes / Q000276:immunology; D006457:Hemoglobinuria, Paroxysmal / Q000150:complications / Q000235:genetics / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000276:immunology*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology*; D008875:Middle Aged; D009154:Mutation; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011971:Receptors, Immunologic / Q000276:immunology; D055607:Receptors, Natural Killer Cell; D013312:Stress, Physiological / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D002352:Carrier Proteins; D058851:GPI-Linked Proteins; D017261:Glycosylphosphatidylinositols; D015395:Histocompatibility Antigens Class I; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; C527085:KLRK1 protein, human; D008565:Membrane Proteins; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011971:Receptors, Immunologic; D055607:Receptors, Natural Killer Cell; C423231:ULBP1 protein, human; C423230:ULBP2 protein, human; C080086:phosphatidylinositol glycan-class A protein