title: Dissection of spontaneous cytotoxicity by human intestinal intraepithelial lymphocytes: MIC on colon cancer triggers NKG2D-mediated lysis through Fas ligand.
abstract: Human intestinal intraepithelial lymphocytes (IELs), which are T-cell receptor alphabeta+ CD8+ T cells located between epithelial cells (ECs), are likely to participate in the innate immune response against colon cancer. IELs demonstrate spontaneous cytotoxic (SC) activity specifically directed against EC tumours but not against other solid tumour types. The aim of this study was to dissect out the mechanism of SC activity, focusing on the interaction of NKG2D on IELs with its ligands [major histocompatibility complex (MHC) class I chain-related protein (MIC) and UL16 binding protein (ULBP)] found mainly on EC tumours. A novel series of events occurred. The NKG2D-MIC/ULBP interaction induced Fas ligand (FasL) production and FasL-mediated SC activity against HT-29 cells and MIC-transfectants. Tumour necrosis factor-alpha and interferon-gamma, produced independently of this interaction, promoted SC activity. The immune synapse was strengthened by the interaction of CD103 on IELs with E-cadherin on HT-29 cells. Neither T-cell receptor nor MHC class I was involved. While the HT-29 cells were destroyed by soluble FasL, tumour necrosis factor-alpha and interferon-gamma, the IELs were resistant to the effects of these mediators and to FasL expressed by the HT-29 cells. This unidirectional FasL-mediated cytotoxicity of IELs against HT-29 cells, triggered through NKG2D, is unique and is likely to be a property of those CD8+ tumour-infiltrating lymphocytes that phenotypically resemble IELs.
authors.affiliation: UMDNJ-Robert Wood Johnson Medical School, New Brunswick, NJ, USA. jeydels@comcast.net
authors.forename: Ellen C
authors.initials: EC
authors.lastname: Ebert
authors.forename: Veronika
authors.initials: V
authors.lastname: Groh
mesh_terms: D000230:Adenocarcinoma / Q000276:immunology* / Q000473:pathology; D002478:Cells, Cultured; D018920:Coculture Techniques; D003110:Colonic Neoplasms / Q000276:immunology* / Q000473:pathology; D003602:Cytotoxicity, Immunologic; D053222:Fas Ligand Protein / Q000276:immunology*; D019073:HT29 Cells; D015395:Histocompatibility Antigens Class I / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology; D007413:Intestinal Mucosa / Q000276:immunology; D015778:Minor Histocompatibility Antigens; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011971:Receptors, Immunologic / Q000276:immunology*; D055607:Receptors, Natural Killer Cell; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D053222:Fas Ligand Protein; D015395:Histocompatibility Antigens Class I; C527085:KLRK1 protein, human; C094840:MR1 protein, human; D015778:Minor Histocompatibility Antigens; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011971:Receptors, Immunologic; D055607:Receptors, Natural Killer Cell; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma