title: Letal, A tumor-associated NKG2D immunoreceptor ligand, induces activation and expansion of effector immune cells.
abstract: NKG2D serves as one of the most potent activating receptors for effector lymphocytes. in peripheral tissues. Here we report the characterization of Letal, the first human trans-membrane NKG2D ligand lacking an immunoglobulin-like alpha-3 ectodomain. Letal is constitutively expressed by a variety of normal tissues, and is upregulated in tumor cells of different origins. Unlike other NKG2D ligands, Letal mRNA expression progressively decreased after treatment of tumor cells with retinoic acid. Simultaneous T-cell receptor activation and engagement of Letal stimulated proliferation of CD8(+) cells and dramatically increased IL-2 and IFNgamma secretion. In addition, Letal induced the killing of cancer cells by CD8(+) and NK cells. These results suggest that Letal delivers activating signals to NK cells and promotes tumor immune surveillance by inducing the expansion of anti-tumor cytotoxic lymphocytes.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007371:Interferon-gamma / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism; D008024:Ligands; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D055655:NK Cell Lectin-Like Receptor Subfamily K; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000276:immunology*; D012333:RNA, Messenger / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*; D055607:Receptors, Natural Killer Cell; D017386:Sequence Homology, Amino Acid; D014212:Tretinoin / Q000627:therapeutic use; D010738:Type C Phospholipases / Q000494:pharmacology
chemical_list: D007074:Immunoglobulin G; D007376:Interleukin-2; C527085:KLRK1 protein, human; C527086:Klrk1 protein, mouse; D008024:Ligands; D055655:NK Cell Lectin-Like Receptor Subfamily K; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D011971:Receptors, Immunologic; D055607:Receptors, Natural Killer Cell; D014212:Tretinoin; D007371:Interferon-gamma; D010738:Type C Phospholipases