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Peripheral Tolerance
In immunology, peripheral tolerance is the second branch of immunological tolerance, after central tolerance. It takes place in the immune periphery (after T and B cells egress from primary lymphoid organs). Its main purpose is to ensure that self-reactive T and B cells which escaped central tolerance do not cause autoimmune disease. Peripheral tolerance prevents immune response to harmless food antigens and allergens, too. Deletion of self-reactive T cells in the thymus is only 60-70% efficient, and naive T cell repertoire contains a significant portion of low-avidity self-reactive T cells. These cells can trigger an autoimmune response, and there are several mechanisms of peripheral tolerance to prevent their activation. Antigen-specific mechanisms of peripheral tolerance include persistent of T cell in quiescence, ignorance of antigen and direct inactivation of effector T cells by either clonal deletion, conversion to regulatory T cells (Tregs) or induction of anergy. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunology
Immunology is a branch of medicineImmunology for Medical Students, Roderick Nairn, Matthew Helbert, Mosby, 2007 and biology that covers the medical study of immune systems in humans, animals, plants and sapient species. In such we can see there is a difference of human immunology and comparative immunology in veterinary medicine and animal biosciences. Immunology measures, uses charts and differentiate in context in medicine the studies of immunity on cell and molecular level, and the immune system as part of the physiological level as its functioning is of major importance. In the different states of both health, occurring symptoms and diseases; the functioning of the immune system and immunological responses such as autoimmune diseases, allergic hypersensitivities, or in some cases malfunctioning of immune system as for example in immunological disorders or in immune deficiency, and the specific transplant rejection) Immunology has applications in numerous disciplines ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CD28
CD28 (Cluster of Differentiation 28) is one of the proteins expressed on T cells that provide co-stimulatory signals required for T cell activation and survival. T cell stimulation through CD28 in addition to the T-cell receptor ( TCR) can provide a potent signal for the production of various interleukins ( IL-6 in particular). CD28 is the receptor for CD80 (B7.1) and CD86 (B7.2) proteins. When activated by Toll-like receptor ligands, the CD80 expression is upregulated in antigen-presenting cells (APCs). The CD86 expression on antigen-presenting cells is constitutive (expression is independent of environmental factors). CD28 is the only B7 receptor constitutively expressed on naive T cells. Association of the TCR of a naive T cell with MHC:antigen complex without CD28:B7 interaction results in a T cell that is anergic. Furthermore, CD28 was also identified on bone marrow stromal cells, plasma cells, neutrophils and eosinophils, but the functional importance of CD28 on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MHC Class I
MHC class I molecules are one of two primary classes of major histocompatibility complex (MHC) molecules (the other being MHC class II) and are found on the cell surface of all nucleated cells in the bodies of vertebrates. They also occur on platelets, but not on red blood cells. Their function is to display peptide fragments of proteins from within the cell to cytotoxic T cells; this will trigger an immediate response from the immune system against a particular non-self antigen displayed with the help of an MHC class I protein. Because MHC class I molecules present peptides derived from cytosolic proteins, the pathway of MHC class I presentation is often called ''cytosolic'' or ''endogenous pathway''. In humans, the HLAs corresponding to MHC class I are HLA-A, HLA-B, and HLA-C. Function Class I MHC molecules bind peptides generated mainly from degradation of cytosolic proteins by the proteasome. The MHC I:peptide complex is then inserted via endoplasmic reticulum into t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PDPN
Podoplanin is a protein that in humans is encoded by the ''PDPN'' gene. Structure and function Podoplanin is a mucin-type protein with a mass of 36- to 43-kDa. It is relatively well conserved between species, with homologues in humans, mice, rats, dogs and hamsters. This gene encodes a type-I, integral membrane, heavily O-glycosylated glycoprotein with diverse distribution in human tissues. The physiological function of this protein may be related to its mucin-type character. The homologous protein in other species has been described as a differentiation antigen and influenza-virus receptor. The specific function of this protein has not been determined but it has been proposed as a marker of lung injury. Alternatively spliced transcript variants encoding different isoforms have been identified. This protein has been found to have functions in lung alveolar cells, kidney podocytes, and lymphatic endothelial cells. More recently, this protein has been found in neural tissue in bot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lymph Node Stromal Cell
Lymph node stromal cells are essential to the structure and function of the lymph node whose functions include: creating an internal tissue scaffold for the support of hematopoietic cells; the release of small molecule chemical messengers that facilitate interactions between hematopoietic cells; the facilitation of the migration of hematopoietic cells; the presentation of antigens to immune cells at the initiation of the adaptive immune system; and the homeostasis of lymphocyte numbers. Stromal cells originate from multipotent mesenchymal stem cells. Structure Lymph nodes are enclosed in an external fibrous capsule, from which thin walls of sinew called ''trabeculae'' penetrate into the lymph node, partially dividing it. Beneath the external capsule and along the courses of the trabeculae, are ''peritrabecular'' and '' subcapsular sinuses''. These sinuses are cavities containing macrophages (specialised cells which help to keep the extracellular matrix in order). The interio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indoleamine 2,3-dioxygenase
Indoleamine-pyrrole 2,3-dioxygenase (IDO or INDO ) is a heme-containing enzyme physiologically expressed in a number of tissues and cells, such as the small intestine, lungs, female genital tract or placenta. In humans is encoded by the ''IDO1'' gene. IDO is involved in tryptophan metabolism. It is one of three enzymes that catalyze the first and rate-limiting step in the kynurenine pathway, the O2-dependent oxidation of L-tryptophan to N-formylkynurenine, the others being indolamine-2,3-dioxygenase 2 (IDO2) and tryptophan 2,3-dioxygenase (TDO). IDO is an important part of the immune system and plays a part in natural defense against various pathogens. It is produced by the cells in response to inflammation and has an immunosuppressive function because of its ability to limit T-cell function and engage mechanisms of immune tolerance. Emerging evidence suggests that IDO becomes activated during tumor development, helping malignant cells escape eradication by the immune system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TRAIL
A trail, also known as a path or track, is an unpaved lane or small road usually passing through a natural area. In the United Kingdom and the Republic of Ireland, a path or footpath is the preferred term for a pedestrian or hiking trail. The term is also applied in North America to routes along rivers, and sometimes to highways. In the US, the term was historically used for a route into or through wild territory used by explorers and migrants (e.g. the Oregon Trail). In the United States, "trace" is a synonym for trail, as in Natchez Trace. Some trails are dedicated only for walking, cycling, horse riding, snowshoeing or cross-country skiing, but not more than one use; others, as in the case of a bridleway in the UK, are multi-use and can be used by walkers, cyclists and equestrians alike. There are also unpaved trails used by dirt bikes and other off-road vehicles, and in some places, like the Alps, trails are used for moving cattle and other livestock. Usage In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BTLA
B- and T-lymphocyte attenuator or BTLA (also known as cluster of differentiation 272 or CD272) is a protein that belongs to the CD28 immunoglobulin superfamily (IgSF) which is encoded by the BTLA gene located on the 3rd human chromosome. BTLA was first discovered in 2003 as an inhibitor of Th1 expansion and it became the 3rd member of the CD28 IgSF. However, its discovered ligand herpes virus entry mediator or HVEM (also known as tumour necrosis factor receptor superfamily member 14 or TNFRSF14) belongs to the tumor necrosis factor receptor superfamily (TNFRSF). This finding was surprising because until the discovery of HVEM it was believed that receptors and ligands always belong to the same family. Expression BTLA is broadly expressed in various organs. Among these are the lymph nodes, the thymus and the spleen where high expression of BTLA can be found. On the contrary, low to no expression is detected in organs such as the liver, kidney, heart, brain and other organs. If we ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lymph Node
A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that include B and T cells. Lymph nodes are important for the proper functioning of the immune system, acting as filters for foreign particles including cancer cells, but have no detoxification function. In the lymphatic system a lymph node is a secondary lymphoid organ. A lymph node is enclosed in a fibrous capsule and is made up of an outer cortex and an inner medulla. Lymph nodes become inflamed or enlarged in various diseases, which may range from trivial throat infections to life-threatening cancers. The condition of lymph nodes is very important in cancer staging, which decides the treatment to be used and determines the prognosis. Lymphadenopathy refers to glands that are enlarged or swollen. When inflamed or enlarged, lymph nodes can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CD86
Cluster of Differentiation 86 (also known as CD86 and B7-2) is a protein constitutively expressed on dendritic cells, Langerhans cells, macrophages, B-cells (including memory B-cells), and on other antigen-presenting cells. Along with CD80, CD86 provides costimulatory signals necessary for T cell activation and survival. Depending on the ligand bound, CD86 can signal for self-regulation and cell-cell association, or for attenuation of regulation and cell-cell disassociation. The ''CD86'' gene encodes a type I membrane protein that is a member of the immunoglobulin superfamily. Alternative splicing results in two transcript variants encoding different isoforms. Additional transcript variants have been described, but their full-length sequences have not been determined. Structure CD86 belongs to the B7 family of the immunoglobulin superfamily. It is a 70 kDa glycoprotein made up of 329 amino acids. Both CD80 and CD86 share a conserved amino acid motif that forms their lig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CD80
The Cluster of differentiation 80 (also CD80 and B7-1) is a B7, type I membrane protein in the immunoglobulin superfamily, with an extracellular immunoglobulin constant-like domain and a variable-like domain required for receptor binding. It is closely related to CD86, another B7 protein (B7-2), and often works in tandem. Both CD80 and CD86 interact with costimulatory receptors CD28 and CTLA-4 (CD152). Structure CD80 is a member of the B7 family, which consists of molecules present at APCs and their receptors present on the T-cells. CD80 is present specifically on DC, activated B-cells, and macrophages, but also T-cells CD80 is also a transmembrane glycoprotein and a member of the Ig superfamily. It is composed of 288 amino acids, and its mass is 33 kDa. It consists of two Ig-like extracellular domains (208 AA), a transmembrane helical segment (21 AA), and a short cytoplasmic tail (25 AA). The Ig-like extracellular domains are formed by single V-type and C2-type domains. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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