Ligands for natural killer cell receptors: redundancy or specificity.
Several inhibitory and activating receptors involved in natural killer cell activation have been characterized. The increasing knowledge about their ligands, including classical MHC class I molecules, non-classical MHC class I molecules and MHC class I-related molecules, is shedding new light on the targets of innate immune recognition. While classical MHC class I molecules are constitutively expressed, some MHC class I-related (MIC) molecules, however, are stress-induced by ill-defined stimuli. Two families of ligands for the human activating NKG2D receptor have been identified. These are the MIC proteins encoded by two highly polymorphic genes within the MHC class I and the retinoic acid-inducible early gene-1-like (also designated UL16-binding) proteins encoded by genes outside the MHC. For the mouse NKG2D receptor, one family, containing at least five distinct ligands, has been described. A better understanding about how targets signal their distress, which renders them susceptible to natural killer (NK)-cell attack, will help to define the role of NK cells in antimicrobial and antitumor immunity and transplantation.
Cerwenka
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Department of Microbiology and Immunology and the Cancer Research Institute, University of California, San Francisco, 94143-0414, USA.
Lanier
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D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D006680:HLA Antigens / Q000378:metabolism; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D037181:Lectins, C-Type; D008024:Ligands; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D051920:NK Cell Lectin-Like Receptor Subfamily D; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011971:Receptors, Immunologic / Q000378:metabolism*; D055607:Receptors, Natural Killer Cell; D015398:Signal Transduction; D000097625:HLA-E Antigens
D015703:Antigens, CD; D006680:HLA Antigens; D015395:Histocompatibility Antigens Class I; D037181:Lectins, C-Type; D008024:Ligands; D008562:Membrane Glycoproteins; D051920:NK Cell Lectin-Like Receptor Subfamily D; D055655:NK Cell Lectin-Like Receptor Subfamily K; D011971:Receptors, Immunologic; D055607:Receptors, Natural Killer Cell; D000097625:HLA-E Antigens; C527085:KLRK1 protein, human; C527086:Klrk1 protein, mouse; C032907:Q surface antigens