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Induced-self Antigen
Induced-self antigen is a marker of abnormal self, which can be recognized upon infected (in particular, virus-infected) and transformed cells. Therefore, the recognition of "induced self" is an important strategy for surveillance of infection or tumor transformation - it results in elimination of the affected cells by activated NK cells or other immunological mechanisms. Similarly γδ T cells can recognize induced-self antigens expressed on cells under stress conditions. Receptors Probably the most studied receptor involved in recognition of induced-self antigens is NKG2D. It is an activating receptor which is expressed on NK cells and subsets of T and NKT cells. NKG2D can bind proteins at the surface of most cells that are not normally expressed, but that are expressed during a stress response of the cells (e.g. induction of the DNA damage pathway). Moreover, other recognition targets exist, for example ligands induced on human macrophages by TLR stimulation. Ligands that bind to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antigen
In immunology, an antigen (Ag) is a molecule, moiety, foreign particulate matter, or an allergen, such as pollen, that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. Antigens can be proteins, peptides (amino acid chains), polysaccharides (chains of simple sugars), lipids, or nucleic acids. Antigens exist on normal cells, cancer cells, parasites, viruses, fungus, fungi, and bacteria. Antigens are recognized by antigen receptors, including antibodies and T-cell receptors. Diverse antigen receptors are made by cells of the immune system so that each cell has a specificity for a single antigen. Upon exposure to an antigen, only the lymphocytes that recognize that antigen are activated and expanded, a process known as clonal selection. In most cases, antibodies are ''antigen-specific'', meaning that an antibody can only react to and bind one specific antigen; in some instances, however, antibodies may cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Killer Cell
Natural killer cells, also known as NK cells, are a type of cytotoxic lymphocyte critical to the innate immune system. They are a kind of large granular lymphocytes (LGL), and belong to the rapidly expanding family of known innate lymphoid cells (ILC) and represent 5–20% of all circulating lymphocytes in humans. The role of NK cells is analogous to that of cytotoxic T cells in the vertebrate adaptive immune response. NK cells provide rapid responses to virus-infected cells, stressed cells, tumor cells, and other intracellular pathogens based on signals from several activating and inhibitory receptors. Most immune cells detect the antigen presented on MHC class I, major histocompatibility complex I (MHC-I) on infected cell surfaces, but NK cells can recognize and kill stressed cells in the absence of antibodies and MHC, allowing for a much faster immune reaction. They were named "natural killers" because of the notion that they do not require activation to kill cells that are m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
γδ T Cells
Gamma delta T cells (γδ T cells) are T cells that have a γδ T-cell receptor (TCR) on their surface. Most T cells are αβ (alpha beta) T cells with TCR composed of two glycoprotein chains called α (alpha) and β (beta) TCR chains. In contrast, γδ T cells have a TCR that is made up of one γ (gamma) chain and one δ (delta) chain. This group of T cells is usually less common than αβ T cells. Their highest abundance is in the gut mucosa, within a population of lymphocytes known as intraepithelial lymphocytes (IELs). The antigenic molecules that activate γδ T cells are largely unknown. γδ T cells are peculiar in that they do not seem to require antigen processing and major histocompatibility complex, major-histocompatibility-complex (MHC) presentation of peptide epitopes, although some recognize MHC class I, MHC class Ib molecules. γδ T cells are believed to have a prominent role in lipid antigen recognition. They are of an invariant nature. They may be triggered by alar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NKG2D
NKG2D is an activating receptor (transmembrane protein) belonging to the NKG2 family of C-type lectin-like receptors. NKG2D is encoded by ''KLRK1'' (killer cell lectin like receptor K1) gene which is located in the NK-gene complex (NKC) situated on chromosome 6 in mice and chromosome 12 in humans. In mice, it is expressed by NK cells, NK1.1+ T cells, γδ T cells, activated CD8+ αβ T cells and activated macrophages. In humans, it is expressed by NK cells, γδ T cells and CD8+ αβ T cells. NKG2D recognizes induced-self proteins from MIC and RAET1/ULBP families which appear on the surface of stressed, malignant transformed, and infected cells. Structure Human NKG2D receptor complex assembles into a hexameric structure. NKG2D itself forms a homodimer whose ectodomains serve for ligand binding. Each NKG2D monomer is associated with DAP10 dimer. This association is maintained by ionic interaction of a positively charged arginine present in a transmembrane segment of NKG2D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MHC Class I Polypeptide-related Sequence A
MHC may refer to: Biology *Major histocompatibility complex, a highly polymorphic region on chromosome 6 with genes particularly involved in immune functions *Myosin heavy chain, part of the motor protein myosin's quaternary protein structure Colleges * Mars Hill College (now Mars Hill University), a college in Mars Hill, North Carolina, USA * Mount Holyoke College, a college in South Hadley, Massachusetts, USA * William E. Macaulay Honors College, an honors college within the City University of New York Health * Managed health care * Mental health counselor * Metropolitan Hospital Center, East Harlem, New York City Sports * Malaysian Hockey Confederation * Mediterranean Handball Confederation * Mid Hudson Conference * Milwaukee Hurling Club Other * Maimonides Heritage Center * Massachusetts Historical Commission * Mile High City, common nickname for the city of Denver, Colorado, due to its elevation of exactly one mile above sea level * Mile high club * Mochoʼ language (IS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NKG2C
NKG2-C type II integral membrane protein or NKG2C is a protein that in humans is encoded by the ''KLRC2'' gene. It is also known as or cluster of differentiation 159c (CD159c). Function Natural killer (NK) cells are lymphocytes that can mediate lysis of certain tumor cells and virus-infected cells without previous activation. They can also regulate specific humoral and cell-mediated immunity. NK cells preferentially express several calcium-dependent (C-type) lectins, which have been implicated in the regulation of NK cell function. The group, designated KLRC (NKG2) are expressed primarily in natural killer (NK) cells and encodes a family of transmembrane proteins characterized by a type II membrane orientation (extracellular C terminus) and the presence of a C-type lectin domain. The KLRC (NKG2) gene family is located within the NK complex, a region that contains several C-type lectin genes preferentially expressed on NK cells. KLRC2 alternative splice variants have been descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
