query: What is an antigen?

title: Antigen processing

text: the bone marrow and mature in the thymus (which accounts for their designation). Link to drawing showing the organs of the immune system. Each B cell and T cell is specific for a particular antigen. What this means is that each is able to bind to a particular molecular structure. The specificity of binding resides in a receptor for antigen: the B cell receptor (BCR) for antigen and the T cell receptor (TCR) respectively. Both BCRs and TCRs share these properties: They are integral membrane proteins. They are present in thousands of identical copies exposed at the cell surface. They

title: Antigen

text: Antigen In immunology, Antigens are substances specifically bound by antibodies or T lymphocyte antigen receptors. They are substances that stimulate production of or are recognized by antibodies. Sometimes antigens are part of the host itself in an autoimmune disease. Antigens are "targeted" by antibodies. Each antibody is specifically produced by the immune system to match an antigen after cells in the immune system come into contact with it; this allows a precise identification or matching of the antigen and the initiation of a tailored response. The antibody is said to "match" the antigen in the sense that it can bind

title: Antigen

text: cannot bind native antigens, but require that they be processed by APCs, whereas B cells can be activated by native ones. Antigenic specificity is the ability of the host cells to recognize an antigen specifically as a unique molecular entity and distinguish it from another with exquisite precision. Antigen specificity is due primarily to the side-chain conformations of the antigen. It is measurable and need not be linear or of a rate-limited step or equation. Antigen In immunology, Antigens are substances specifically bound by antibodies or T lymphocyte antigen receptors. They are substances that stimulate production of or are recognized

title: Antigen

text: to it due to an adaptation in a region of the antibody; because of this, many different antibodies are produced, each able to bind a different antigen while sharing the same basic structure. In most cases, an adapted antibody can only react to and bind one specific antigen; in some instances, however, antibodies may cross-react and bind more than one antigen. Also, an antigen is a molecule that binds to Ag-specific receptors, but cannot necessarily induce an immune response in the body by itself. Antigens are usually proteins, peptides (amino acid chains) and polysaccharides (chains of monosaccharides/simple sugars) but lipids

title: Antigen presentation

text: Antigen presentation Antigen presentation describes a vital immune process which is essential for T cell immune response triggering. Because T cells recognise only fragmented antigens displayed on cell surfaces, antigen processing must occur before the antigen fragment, now bound to the major histocompatibility complex (MHC), is transported to the surface of the cell, a process known as presentation, where it can be recognized by a T cell receptor. If there has been an infection with viruses or bacteria, the cell will present an endogenous or exogenous peptide fragment derived from the antigen bound to MHC molecules. There are two types

title: Antigen

text: in the activation of the innate immune system. An immunogen is an antigen substance (or adduct) that is able to trigger a humoral (innate) or cell-mediated immune response. It first initiates an innate immune response, which then causes the activation of the adaptive immune response. An antigen binds the highly variable immunoreceptor products (B cell receptor or T cell receptor) once these have been generated. Immunogens are those antigens, termed immunogenic, capable of inducing an immune response. At the molecular level, an antigen can be characterized by its ability to bind to an antibody's variable Fab region. Different antibodies have

title: Antigen

text: processing, transport into the endoplasmic reticulum, affinity for the relevant MHC class I alleles and gene expression or protein translation levels. The majority of human neoantigens identified in unbiased screens display a high predicted MHC binding affinity. Minor histocompatibility antigens, a conceptually similar antigen class are also correctly identified by MHC binding algorithms. Another potential filter examines whether the mutation is expected to improve MHC binding. The nature of the central TCR-exposed residues of MHC-bound peptides is associated with peptide immunogenicity. A native antigen is an antigen that is not yet processed by an APC to smaller parts. T cells

title: Antigen processing

text: Antigen processing "'Antigen processing" or cytosolic' pathway is an immunological process that prepares antigens for presentation to special cells of the immune system called T lymphocytes. It is considered to be a stage of antigen presentation pathways. This process involves two distinct pathways for processing of antigens from an organism's own (self) proteins or intracellular pathogens (e.g. viruses), or from phagocytosed pathogens (e.g. bacteria); subsequent presentation of these antigens on class I or class II major histocompatibility complex (MHC) molecules is dependent on which pathway is used. Both MHC class I and II are required to bind antigen before they

title: Antigen processing

text: are made before the cell ever encounters an antigen. They are encoded by genes assembled by the recombination of segments of DNA. How antigen receptor diversity is generated. They have a unique binding site. This site binds to a portion of the antigen called an antigenic determinant or epitope. The binding, like that between an enzyme and its substrate depends on complementarity of the surface of the receptor and the surface of the epitope. The binding occurs by non-covalent forces (again, like an enzyme binding to its substrate). Successful binding of the antigen receptor to the epitope, if accompanied by

title: Antigen retrieval

text: Antigen retrieval Tissues that have been preserved with formaldehyde, a highly reactive compound, contain a variety of chemical modifications that can reduce the detectability of proteins in biomedical procedures such as immunohistochemistry. Antigen retrieval is an approach to reducing or eliminating these chemical modifications. The two primary methods of antigen retrieval are heat-mediated epitope retrieval (HIER) and proteolytic induced epitope retrieval (PIER). It's the cleavage of peptides, exposing the antigen; uses enzymes including Proteinase K, Trypsin, and Pepsin. It has low success rate for restoring immunoreactivity and potentially destroys both tissue morphology and the antigen of interest. It's the reversal

title: Antigen processing

text: a gamma chain paired with a delta chain. The discussion that follows now concerns alpha/beta T cells. Gamma/delta T cells, which are less well understood. The TCR (of alpha/beta T cells) binds a bimolecular complex displayed at the surface of some other cell called an antigen-presenting cell (APC). This complex consists of: a fragment of an antigen lying within the groove of a histocompatibility molecule The complex has been compared to a "hot dog in a bun". Antigen processing "'Antigen processing" or cytosolic' pathway is an immunological process that prepares antigens for presentation to special cells of the immune system

title: Oncofetal antigen

text: antigen protein). Oncofetal antigens are promising targets for vaccination against several types of cancers. Oncofetal antigen Oncofetal antigens are proteins which are typically present only during fetal development but are found in adults with certain kinds of cancer. These proteins are often measurable in the blood of individuals with cancer and may be used to both diagnose and follow treatment of the tumors. One example of an oncofetal antigen is alpha-fetoprotein, which is produced by hepatocellular carcinoma and some germ cell tumors. Another example is carcinoembryonic antigen, which is elevated in people with colon cancer and other tumors. Other oncofetal

title: Middle tumor antigen

text: of breast cancer. Middle tumor antigen The middle tumor antigen (also called the middle T-antigen and abbreviated MTag or MT) is a protein encoded in the genomes of some polyomaviruses, which are small double-stranded DNA viruses. MTag is expressed early in the infectious cycle along with two other related proteins, the small tumor antigen and large tumor antigen. MTag occurs only in a few known polyomaviruses, while STag and LTag are universal - it was first identified in mouse polyomavirus (MPyV), the first polyomavirus discovered, and also occurs in hamster polyomavirus. In MPyV, MTag is an efficient oncoprotein that can

title: Middle tumor antigen

text: Middle tumor antigen The middle tumor antigen (also called the middle T-antigen and abbreviated MTag or MT) is a protein encoded in the genomes of some polyomaviruses, which are small double-stranded DNA viruses. MTag is expressed early in the infectious cycle along with two other related proteins, the small tumor antigen and large tumor antigen. MTag occurs only in a few known polyomaviruses, while STag and LTag are universal - it was first identified in mouse polyomavirus (MPyV), the first polyomavirus discovered, and also occurs in hamster polyomavirus. In MPyV, MTag is an efficient oncoprotein that can be sufficient to

title: Antigen-antibody interaction

text: Antigen-antibody interaction Antigen-antibody interaction, or antigen-antibody reaction, is a specific chemical interaction between antibodies produced by B cells of the white blood cells and antigens during immune reaction. It is the fundamental reaction in the body by which the body is protected from complex foreign molecules, such as pathogens and their chemical toxins. In the blood, the antigens are specifically and with high affinity bound by antibodies to form an antigen-antibody complex. The immune complex is then transported to cellular systems where it can be destroyed or deactivated. The first correct description of the antigen-antibody reaction was given by Richard

title: Forssman antigen

text: Forssman antigen The Forssman Antigen is a glycolipid heterophil protein and a type of heterogenetic antigen found in certain animals like dogs, horses, cats, turtles and sheep, including enteric organisms such as pneumococci. In sheep, it is found in their erythrocytes but not on tissue and organs, except for hamsters and guinea pigs. The Forssman antigen is distinct from the Paul-Bunnell antigen, antibodies to which are diagnostic of glandular fever (infectious mononucleosis). Both antigens are present on the red blood cells of horse and sheep but guinea pig kidney cells have only the Forssman antigen. A serum positive for glandular

title: Antigen retrieval

text: of cross-links and restoration of protein structures by heat; method efficiency dependent on time, temperature, buffer and pH. In general HIER allows better antigen retrieval than PIER. It's the reversal of cross-links using acids such as hydrochloric acid (pH 1) or formic acid (pH 2). Antigen retrieval Tissues that have been preserved with formaldehyde, a highly reactive compound, contain a variety of chemical modifications that can reduce the detectability of proteins in biomedical procedures such as immunohistochemistry. Antigen retrieval is an approach to reducing or eliminating these chemical modifications. The two primary methods of antigen retrieval are heat-mediated epitope retrieval

title: Antigen

text: be recognized by highly variable antigen receptors (B-cell receptor or T-cell receptor) of the adaptive immune system. The antigen may originate from within the body ("self-antigen") or from the external environment ("non-self"). The immune system is supposed to identify and attack "non-self" invaders from the outside world or modified/harmful substances present in the body and usually does not react to self-antigens under normal homeostatic conditions due to negative selection of T cells in the thymus. Vaccines are examples of antigens in an immunogenic form, which are intentionally administered to a recipient to induce the memory function of adaptive immune system

title: Antigen-presenting cell

text: Antigen-presenting cell An antigen-presenting cell (APC) or accessory cell is a cell that displays antigen complexed with major histocompatibility complexes (MHCs) on their surfaces; this process is known as antigen presentation. T cells may recognize these complexes using their T cell receptors (TCRs). These cells process antigens and present them to T-cells. Almost all cell types can serve as some form of APC. They are found in a variety of tissue types. Professional antigen-presenting cells, including macrophages, B cells and dendritic cells, present foreign antigens to helper T cells, while other cell types can present antigens originating inside the cell

title: Antigen

text: The "Oxford English Dictionary" indicates that the logical construction should be "anti(body)-gen". Antigen presenting cells present antigens in the form of peptides on histocompatibility molecules. The T cell selectively recognize the antigens; depending on the antigen and the type of the histocompatibility molecule, different types of T cells will be activated. For T Cell Receptor (TCR) recognition, the peptide must be processed into small fragments inside the cell and presented by a major histocompatibility complex (MHC). The antigen cannot elicit the immune response without the help of an immunologic adjuvant. Similarly, the adjuvant component of vaccines plays an essential role

title: Oncofetal antigen

text: Oncofetal antigen Oncofetal antigens are proteins which are typically present only during fetal development but are found in adults with certain kinds of cancer. These proteins are often measurable in the blood of individuals with cancer and may be used to both diagnose and follow treatment of the tumors. One example of an oncofetal antigen is alpha-fetoprotein, which is produced by hepatocellular carcinoma and some germ cell tumors. Another example is carcinoembryonic antigen, which is elevated in people with colon cancer and other tumors. Other oncofetal antigens are trophoblast glycoprotein precursor and immature laminin receptor protein (also known as oncofetal

title: Apical membrane antigen 1

text: Apical membrane antigen 1 In molecular biology, apical membrane antigen 1 is a novel antigen of "Plasmodium falciparum" which has been cloned. It contains a hydrophobic domain typical of an integral membrane protein. The antigen is designated apical membrane antigen 1 (AMA-1) by virtue of appearing to be located in the apical complex. AMA-1 appears to be transported to the merozoite surface close to the time of schizont rupture. The 66kDa merozoite surface antigen (PK66) of "Plasmodium knowlesi", a simian malaria, possesses vaccine-related properties believed to originate from a receptor-like role in parasite invasion of erythrocytes. The sequence of PK66

title: Antigen presentation

text: the form of immune complexes. Some APCs expressing comparatively lower levels of lysosomal enzymes are thus less likely to digest the antigen they have captured before presenting it to B cells. Antigen presentation Antigen presentation describes a vital immune process which is essential for T cell immune response triggering. Because T cells recognise only fragmented antigens displayed on cell surfaces, antigen processing must occur before the antigen fragment, now bound to the major histocompatibility complex (MHC), is transported to the surface of the cell, a process known as presentation, where it can be recognized by a T cell receptor. If

title: Heterophile antigen

text: Heterophile antigen Heterophile antigens are antigens of similar nature, if not identical, that are present in different tissues in different biological species, classes or kingdoms. Usually different species have different antigen sets but the hetereophile antigen is shared by different species. Other heterophile antigens are responsible for some diagnostic serological tests such as: Chemically, heterophile antigens are composed of lipoprotein-polysaccharide complexes. There is a possibility of there being identical chemical groupings in the structure of mucopolysaccharids and lipids. Example: Forssman antigen, cross reacting microbial antigen so antibodies to these antigens produced by one species cross react with antigens of other

title: Small tumor antigen

text: Small tumor antigen The small tumor antigen (also called the small T-antigen and abbreviated STag or ST) is a protein encoded in the genomes of polyomaviruses, which are small double-stranded DNA viruses. STag is expressed early in the infectious cycle and is usually not essential for viral proliferation, though in most polyomaviruses it does improve replication efficiency. The STag protein is expressed from a gene that overlaps the large tumor antigen (LTag) such that the two proteins share an N-terminal DnaJ-like domain but have distinct C-terminal regions. STag is known to interact with host cell proteins, most notably protein phosphatase

title: Lewis antigen system

text: in secretions and in the serum. Type 2 is found exclusively on the surface of red blood cells. No type 1 oligosaccharide is found on RBCs. Unbranched type 1 and 2 oligosaccharides represent "i antigen". Branched type 1 and 2 oligosaccharides are "I antigens". In neonates, "i antigen" oligosaccharides predominate (high in cord blood samples). Oligosaccharide branching increases with age, thus adults have mostly "I antigen". The H gene of the ABO system encodes a fucosyltransferase that adds fucose to type 2 precursor substances on the surface of RBCs to make H antigen. The h gene is an amorph. If

title: Antigen-presenting cell

text: proteins, co-stimulatory molecules and the necessary peptides. The APC activator IMP321 is being tested in clinical trials to accelerate the immune reaction to eliminate metastatic breast cancer or melanoma. Antigen-presenting cell An antigen-presenting cell (APC) or accessory cell is a cell that displays antigen complexed with major histocompatibility complexes (MHCs) on their surfaces; this process is known as antigen presentation. T cells may recognize these complexes using their T cell receptors (TCRs). These cells process antigens and present them to T-cells. Almost all cell types can serve as some form of APC. They are found in a variety of tissue

title: H-Y antigen

text: H-Y antigen H-Y antigen is a male tissue specific antigen. Originally thought to trigger the formation of testes (via loci, an autosomal gene that generates the antigen and one that generates the receptor.), it is now known that it doesn't trigger the formation of testes but may be activated by the formation of testes. There are several antigens which qualify as H-Y as defined by rejection of male skin grafts in female hosts or detected by cytotoxic T cells or antibodies. One H-Y, secreted by the testis, defined by antibodies, is identical to müllerian-inhibiting substance (AMH gene). Another H-Y, minor

title: Kidd antigen system

text: an antibody directed against a new antigen Jk (a). Whereas Jk (b) was discovered by Plant et al. in 1953, individuals who lack the Jk antigen (Jk null) are unable to maximally concentrate their urine. The Jk antigen is important in transfusion medicine. People with two Jk(a) antigens, for instance, may form antibodies against donated blood containing two Jk(b) antigens (and thus no Jk(a) antigens). This can lead to hemolytic anemia, in which the body destroys the transfused blood, leading to low red blood cell counts. Another disease associated with the Jk antigen is hemolytic disease of the newborn (HDN),

title: Colton antigen system

text: Colton antigen system The Colton antigen system (Co) is present on the membranes of red blood cells and in the tubules of the kidney and helps determine a person's blood type. The Co antigen is found on a protein called aquaporin-1 which is responsible for water homeostasis and urine concentration. The Co antigen is important in transfusion medicine. 99.8% of people possess the Co(a) allele. Individuals with Co(b) allele or who are missing the Colton antigen are at risk for a transfusion reaction such as hemolytic anemia or alloimmunization. Antibodies against the Colton antigen may also cause hemolytic disease of

title: Antigen presentation

text: the plasma membrane and the processed antigen is presented to the helper T cells in the lymph nodes. APCs undergo a process of maturation while migrating, via chemotactic signals, to lymphoid tissues, in which they lose the phagocytic capacity and develop an increased ability to communicate with T-cells by antigen-presentation. As well as in CD8+ cytotoxic T cells, APCs need pMHC-II and additional costimulatory signals to fully activate naive T helper cells. Alternative pathway of endogenous antigen processing and presentation over MHC-II molecules exists in medullary thymic epithelial cells (mTEC) via the process of autophagy. It is important for the

title: Heterophile antigen

text: species. It is widely present in some plants bacteria animal and birds. However it is not present in rabbit. Therefore antibodies are produced in rabbit serum by injecting the antigen (antiforssman antibodies). Heterophile antigen Heterophile antigens are antigens of similar nature, if not identical, that are present in different tissues in different biological species, classes or kingdoms. Usually different species have different antigen sets but the hetereophile antigen is shared by different species. Other heterophile antigens are responsible for some diagnostic serological tests such as: Chemically, heterophile antigens are composed of lipoprotein-polysaccharide complexes. There is a possibility of there being

title: Antigen-presenting cell

text: T cells and NK cells by using the CD1 family of proteins, which are structurally similar to the MHC class I family. Professional APCs specialize in presenting antigen to T cells. They are very efficient at internalizing antigens, either by phagocytosis (macrophages and dendritic cells) or by receptor-mediated endocytosis (B cells), processing the antigen into peptide fragments and then displaying those peptides, bound to a class II MHC molecule, on their membrane. The T cell recognizes and interacts with the antigen-class II MHC molecule complex on the membrane of the antigen-presenting cell. An additional co-stimulatory signal is then produced by

title: Carcinoembryonic antigen

text: monoclonal antibodies to CEA tend to have some degree of cross-reactivity, occasionally giving false positive results, it is commonly employed in combination with other immunohistochemistry tests, such as those for BerEp4, WT1, and calretinin. CEA and related genes make up the CEA family belonging to the immunoglobulin superfamily. In humans, the carcinoembryonic antigen family consists of 29 genes, 18 of which are normally expressed. The following is a list of human genes which encode carcinoembryonic antigen-related cell adhesion proteins: CEACAM1, CEACAM3, CEACAM4, CEACAM5, CEACAM6, CEACAM7, CEACAM8, CEACAM16, CEACAM18, CEACAM19, CEACAM20, CEACAM21 Carcinoembryonic antigen Carcinoembryonic antigen (CEA) describes a set of

title: Goodpasture-antigen-binding protein kinase

text: Goodpasture-antigen-binding protein kinase In enzymology, a Goodpasture-antigen-binding protein kinase () is an enzyme that catalyzes the chemical reaction Thus, the two substrates of this enzyme are ATP and Goodpasture antigen-binding protein, whereas its two products are ADP and Goodpasture antigen-binding phosphoprotein. This enzyme belongs to the family of transferases, specifically those transferring a phosphate group to the sidechain oxygen atom of serine or threonine residues in proteins (protein-serine/threonine kinases). The systematic name of this enzyme class is ATP:[Goodpasture antigen-binding protein] phosphotransferase. Other names in common use include GPBPK, GPBP kinase, STK11, and Goodpasture antigen-binding protein kinase. This enzyme participates in

title: Colton antigen system

text: the newborn, in which a pregnant woman's body creates antibodies against the blood of her fetus, leading to destruction of the fetal blood cells. Colton antigen system The Colton antigen system (Co) is present on the membranes of red blood cells and in the tubules of the kidney and helps determine a person's blood type. The Co antigen is found on a protein called aquaporin-1 which is responsible for water homeostasis and urine concentration. The Co antigen is important in transfusion medicine. 99.8% of people possess the Co(a) allele. Individuals with Co(b) allele or who are missing the Colton antigen

title: Tumor antigen vaccine

text: of the antigen used in the vaccine tested in Phase 1/2 clinical trials for each of 10 different cancers: Tumor antigen vaccine According to the National Cancer Institute, a tumor antigen vaccine is a "vaccine made of cancer cells, parts of cancer cells, or pure tumor antigens (substances isolated from tumor cells)". A tumor antigen vaccine may stimulate the body's immune system to find and kill cancer cells. As such, tumor antigen vaccines are a type of cancer immunotherapy. Tumor antigen vaccines work the same way that viral vaccines work, by training the immune system to attack cells that contain

title: Antigen processing

text: are stably expressed on a cell surface. MHC I antigen presentation typically (considering cross-presentation) involves the endogenous pathway of antigen processing, and MHC II antigen presentation involves the exogenous pathway of antigen processing. Cross-presentation involves parts of the exogenous and the endogenous pathways but ultimately involves the latter portion of the endogenous pathway (e.g. proteolysis of antigens for binding to MHC I molecules). While the joint distinction between the two pathways is useful, there are instances where extracellular-derived peptides are presented in the context of MHC class I and cytosolic peptides are presented in the context of MHC class II

title: Tumor antigen vaccine

text: Tumor antigen vaccine According to the National Cancer Institute, a tumor antigen vaccine is a "vaccine made of cancer cells, parts of cancer cells, or pure tumor antigens (substances isolated from tumor cells)". A tumor antigen vaccine may stimulate the body's immune system to find and kill cancer cells. As such, tumor antigen vaccines are a type of cancer immunotherapy. Tumor antigen vaccines work the same way that viral vaccines work, by training the immune system to attack cells that contain the antigens in the vaccine. The difference is that the antigens for viral vaccines are derived from viruses or

title: Sp100 nuclear antigen

text: Sp100 nuclear antigen Sp100 nuclear antigen is an interferon stimulated antigen found in the cell nuclei of many human and higher animal cells. Autoantibodies directed against Sp100 are often found in patients with primary biliary cirrhosis. Histologically Sp100 'dots' regions of the cell nucleus. Viral infection and mitogens affect the expression of the Sp100 autoantigen. Cells grown in the presence of interferons (α, β, and γ) revealed an increase both in size and number of the Sp100 protein-containing nuclear dots and increase the protein concentration. This raises "the question whether cytokine-mediated increase of Sp100 protein expression plays a role in

title: T independent antigen (TI)

text: by dendritic cells (DC) and macrophages is required. T independent antigen (TI) T independent antigen elicits antibody production by B lymphocytes without T lymphocyte involvement. There are 2 distinct subgroups of TI antigens, different in mechanism of activating B lymphocytes. TI-1 antigen, which has an activity that can directly activate B cells and TI-2 antigen, which has highly repetitive structure and causes simultaneous cross-linking of specific B cell receptors (BCR) on B lymphocyte. The most commonly released isotype of antibodies in this type of immune reaction is low affinity IgM. For most protein antigens, the production of antibodies by B

title: T independent antigen (TI)

text: T independent antigen (TI) T independent antigen elicits antibody production by B lymphocytes without T lymphocyte involvement. There are 2 distinct subgroups of TI antigens, different in mechanism of activating B lymphocytes. TI-1 antigen, which has an activity that can directly activate B cells and TI-2 antigen, which has highly repetitive structure and causes simultaneous cross-linking of specific B cell receptors (BCR) on B lymphocyte. The most commonly released isotype of antibodies in this type of immune reaction is low affinity IgM. For most protein antigens, the production of antibodies by B lymphocytes is dependent on stimulation of helper T

title: Duffy antigen system

text: "P. falciparum. The Duffy antigen binding protein in "P. vivax" is composed of three subdomains and is thought to function as a dimer. The critical DARC binding residues are concentrated at the dimer interface and along a relatively flat surface spanning portions of two subdomains. A study in Brazil confirmed the protective effect of FY*A/FY*O against malaria. In contrast the genotype FY*B/FY*O was associated with a greater risk. An increased incidence of Duffy antigen has been reported in patients with multiple myeloma compared with healthy controls. The Duffy antigen is present in the normal pulmonary vascular bed. Its expression is

title: Antigen

text: and nucleic acids become antigens only when combined with proteins and polysaccharides. In general, saccharides and lipids (as opposed to peptides) qualify as antigens but not as immunogens since they cannot elicit an immune response on their own. Furthermore, for a peptide to induce an immune response (activation of T-cells by antigen-presenting cells) it must be a large enough size, since peptides too small will also not elicit an immune response. The term antigen originally described a structural molecule that binds specifically to an antibody. It was expanded to refer to any molecule or a linear molecular fragment that can

text: mTOR signaling pathway and adipocytokine signaling pathway. Goodpasture-antigen-binding protein kinase In enzymology, a Goodpasture-antigen-binding protein kinase () is an enzyme that catalyzes the chemical reaction Thus, the two substrates of this enzyme are ATP and Goodpasture antigen-binding protein, whereas its two products are ADP and Goodpasture antigen-binding phosphoprotein. This enzyme belongs to the family of transferases, specifically those transferring a phosphate group to the sidechain oxygen atom of serine or threonine residues in proteins (protein-serine/threonine kinases). The systematic name of this enzyme class is ATP:[Goodpasture antigen-binding protein] phosphotransferase. Other names in common use include GPBPK, GPBP kinase, STK11, and Goodpasture

title: MNS antigen system

text: irrelevant for transfusion since this variant of the antibody does not react at body temperature. The S antigen is relatively common (~55% of the population) and the s antigen is very common (~89% of the population). Anti-S and anti-s can cause hemolytic transfusion reactions and hemolytic disease of the newborn. The U antigen is a high incidence antigen, occurring in more than 99.9% of the population. The U was originally short for "Universal", though this is not the case. U negative RBCs can be found in people of African descent. This mutation in red cell surface structure also makes the

title: Kidd antigen system

text: Kidd antigen system The Kidd antigen system (also known as Jk antigen) is present on the membranes of red blood cells and the kidney and helps determine a person's blood type. The Jk antigen is found on a protein responsible for urea transport in the red blood cells and the kidney. The gene encoding this protein is found on chromosome 18. Three Jk alleles are Jk (a), Jk (b)and Jk3. Jk (a) was discovered by Allen et al. in 1951 and is named after a patient (Mrs Kidd delivered a baby with a haemolytic disease of the newborn associated with

title: Sp100 nuclear antigen

text: defines a novel protein motif, the HNPP-box. Another class of variants has high mobility group 1 (HMG1) protein sequence as a domain. Both major classes of Sp100 splice variant proteins localize in part to nuclear dots/PML bodies and other nuclear domains. Sp100 nuclear antigen Sp100 nuclear antigen is an interferon stimulated antigen found in the cell nuclei of many human and higher animal cells. Autoantibodies directed against Sp100 are often found in patients with primary biliary cirrhosis. Histologically Sp100 'dots' regions of the cell nucleus. Viral infection and mitogens affect the expression of the Sp100 autoantigen. Cells grown in the

title: Forssman antigen

text: fever therefore agglutinates horse or sheep red blood cells after absorption with guinea pig kidney (see Basson V, Sharp AA (May 1969). "Monospot: a differential slide test for infectious mononucleosis". J. Clin. Pathol. 22 (3): 324–5. . . .) It is named for John Frederick Forssman (1868 – 1947), a pioneer Swedish Pathologist, who described it in 1930. Forssman antigen The Forssman Antigen is a glycolipid heterophil protein and a type of heterogenetic antigen found in certain animals like dogs, horses, cats, turtles and sheep, including enteric organisms such as pneumococci. In sheep, it is found in their erythrocytes but

title: Thomsen–Friedenreich antigen

text: Thomsen–Friedenreich antigen according to the biochemical and serological analysis presented here. In contrast to studies performed in the past, immunohistochemical results using the antibody 82-A6 did not exhibit a reactivity clearly restricted to tumors. Preliminary biochemical analysis revealed that the T-determinant is detectable in the high-molecular weight range (about 1000 kD), suggesting that the Gal-GalNAc epitope is found on mucin-like glycoproteins. Tumor restriction of the Thomsen–Friedenreich antigen may therefore be determined either by the protein backbone or by the beta-glycosidic linkage of the carbohydrate structure to the protein. Thomsen–Friedenreich antigen Thomsen–Friedenreich antigen (Galβ1-3GalNAcα1) is a disaccharide. It is usually present

title: Antigen-presenting cell

text: cells fall into two categories: professional and non-professional. Those that express MHC class II molecules along with co-stimulatory molecules and pattern recognition receptors are often called professional antigen-presenting cells. The non-professional APCs express MHC class I molecules. T cells must be activated by interacting with a professional APC presenting an antigen which their T cell receptor recognizes before they can divide and perform their function. The APC involved in activating T cells is usually a dendritic cell. T cells cannot recognize and therefore cannot respond to, 'free' or soluble antigens. They can only recognize and respond to antigen that has

title: Antigen-presenting cell

text: to cytotoxic T cells. In addition to the MHC family of proteins, antigen presentation relies on other specialized signaling molecules on the surfaces of both APCs and T cells. Antigen-presenting cells are vital for effective adaptive immune response, as the functioning of both cytotoxic and helper T cells is dependent on APCs. Antigen presentation allows for specificity of adaptive immunity and can contribute to immune responses against both intracellular and extracellular pathogens. It is also involved in defense against tumors. Some cancer therapies involve the creation of artificial APCs to prime the adaptive immune system to target malignant cells. Antigen-presenting

title: Tumor antigen

text: Cells infected by these viruses contain latent viral DNA which is transcribed and the resulting protein produces an immune response. In addition to proteins, other substances like cell surface glycolipids and glycoproteins may also have an abnormal structure in tumor cells and could thus be targets of the immune system. Tumor antigens, because of their relative abundance in tumor cells are useful in identifying specific tumor cells. Certain tumors have certain tumor antigens in abundance. Certain tumor antigens are thus used as tumor markers. More importantly, tumor antigens can be used in cancer therapy as tumor antigen vaccines. Tumor antigen

title: Kidd antigen system

text: hemolyzed by 2M urea. This can be used as a screening test for Jk(a-b-) donors. The Jk(a-b-) phenotype has no clinical defect, although two individuals with this phenotype have been reported to have mild urine-concentrating defects. Kidd antibodies are capable of behaving as histocompatibility antigens in renal transplants and may be responsible for allograft rejection in some cases. Kidd antigen system The Kidd antigen system (also known as Jk antigen) is present on the membranes of red blood cells and the kidney and helps determine a person's blood type. The Jk antigen is found on a protein responsible for urea

title: Apical membrane antigen 1

text: is conserved throughout plasmodium, and shows high similarity to P. falciparum AMA-1. Following schizont rupture, the distribution of PK66 changes in a coordinate manner associated with merozoite invasion. Prior to rupture, the protein is concentrated at the apical end, following which it distributes itself entirely across the surface of the free merozoite. Immunofluorescence studies suggest that, during invasion, PK66 is excluded from the erythrocyte at, and behind, the invasion interface. Apical membrane antigen 1 In molecular biology, apical membrane antigen 1 is a novel antigen of "Plasmodium falciparum" which has been cloned. It contains a hydrophobic domain typical of an

title: Tumor antigen

text: Tumor antigen Tumor antigen is an antigenic substance produced in tumor cells, i.e., it triggers an immune response in the host. Tumor antigens are useful tumor markers in identifying tumor cells with diagnostic tests and are potential candidates for use in cancer therapy. The field of cancer immunology studies such topics. Normal proteins in the body are not antigenic because of self-tolerance, a process in which self-reacting cytotoxic T lymphocytes (CTLs) and autoantibody-producing B lymphocytes are culled "centrally" in primary lymphatic tissue (BM) and "peripherally" in secondary lymphatic tissue (mostly thymus for T-cells and spleen/lymph nodes for B cells). Thus

title: Antigen-presenting cell

text: been processed and presented by cells via carrier molecules like MHC molecules. Helper T cells can recognize exogenous antigen presented on MHC class II; cytotoxic T cells can recognize endogenous antigen presented on MHC class I. Most cells in the body can present antigen to CD8+ cytotoxic T cells via MHC class I ; however, the term "antigen-presenting cell" is often used specifically to describe professional APCs. Such cells express MHC class I and MHC class II molecules and can stimulate CD4+ helper T cells as well as cytotoxic T cells. APCs can also present foreign and self lipids to

title: SV40 large T antigen

text: are heavily dependent on the cell for transcription and genome replication. The cis-acting regulatory element surrounding the origin of replication directs transcription, and T-antigen directs transcription and replication. SV40 DNA replication is initiated by binding of large T-antigen to the origin region of the genome. The function of T-antigen is controlled by phosphorylation, which attenuates the binding to the SV40 origin. Protein-protein interactions between T-antigen and DNA polymerase-alpha directly stimulate replication of the virus genome. T-antigen also binds and inactivates tumor suppressor proteins (p53, p105-Rb). This causes the cells to leave G1 phase and enter into S phase, which promotes

title: Antigen processing

text: surface of antigen-presenting cells like macrophages and dendritic cells. The bound antigen molecules are engulfed into the B cell by receptor-mediated endocytosis. The antigen is digested into fragments which are then displayed at the cell surface nestled inside a class II histocompatibility molecule. Helper T cells specific for this structure (i.e., with complementary TCRs) bind the B cell and secrete lymphokines that: stimulate the B cell to enter the cell cycle and develop, by repeated mitosis, into a clone of cells with identical BCRs; Link to discussion of clonal selection. switch from synthesizing their BCRs as integral membrane proteins to

title: Sjögren syndrome antigen B

text: interact with nucleolin. Sjögren syndrome antigen B Sjögren syndrome type B antigen (SS-B) also known as Lupus La protein is a protein that in humans is encoded by the "SSB" gene. La is involved in diverse aspects of RNA metabolism, including binding and protecting 3-prime UUU (OH) elements of newly RNA polymerase III-transcribed RNA, processing 5-prime and 3-prime ends of pre-tRNA precursors, acting as an RNA chaperone, and binding viral RNAs associated with hepatitis C virus. La protein was originally defined by its reactivity with autoantibodies from patients with Sjögren's syndrome and systemic lupus erythematosus. Sjögren syndrome antigen B has

title: Sjögren syndrome antigen B

text: Sjögren syndrome antigen B Sjögren syndrome type B antigen (SS-B) also known as Lupus La protein is a protein that in humans is encoded by the "SSB" gene. La is involved in diverse aspects of RNA metabolism, including binding and protecting 3-prime UUU (OH) elements of newly RNA polymerase III-transcribed RNA, processing 5-prime and 3-prime ends of pre-tRNA precursors, acting as an RNA chaperone, and binding viral RNAs associated with hepatitis C virus. La protein was originally defined by its reactivity with autoantibodies from patients with Sjögren's syndrome and systemic lupus erythematosus. Sjögren syndrome antigen B has been shown to

title: Large tumor antigen

text: splicing. The LTag gene is usually encoded in two exons, of which the first overlaps with the gene for the small tumor antigen (STag); as a result, the two proteins share an N-terminal sequence of around 80 residues, while the remaining ~90 residues of STag are unshared. In a few polyomaviruses - most notably murine polyomavirus, the first member of the family discovered and an efficient oncovirus - an additional protein called middle tumor antigen is expressed from the early region and is highly efficient at cellular transformation. Some, but not all, polyomaviruses are oncoviruses capable of inducing neoplastic transformation

title: Duffy antigen system

text: the spleen, liver and kidney and the large pulmonary venules. In some people who lack the Duffy antigen on their erythrocytes it may still be expressed in some cells. It has two potential N-linked glycosylation sites at asparagine (Asn) 16 and Asn27. The Duffy antigen has been found to act as a multispecific receptor for chemokines of both the C-C and C-X-C families, including: and the angiogenic CXC chemokines: Consequently, the Fy protein is also known as DARC (Duffy Antigen Receptor for Chemokines). The chemokine binding site on the receptor appears to be localised to the amino terminus. The antigen

title: Antigen-presenting cell

text: the antigen-presenting cell, leading to activation of the T cell. The expression of co-stimulatory molecules and MHC class II are defining features of professional APCs. All professional APCs also express MHC class I molecules as well. The main types of professional antigen-presenting cells are dendritic cells, macrophages and B cells. Dendritic cells have the broadest range of antigen presentation and are necessary for activation of naive T cells. DCs present antigen to both helper and cytotoxic T cells. They can also perform cross-presentation, a process by which they present exogenous antigen on MHC class I molecules to cytotoxic T cells.

title: Induced-self antigen

text: 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. 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

title: Duffy antigen system

text: Duffy antigen system Duffy antigen/chemokine receptor (DARC), also known as Fy glycoprotein (FY) or CD234 (Cluster of Differentiation 234), is a protein that in humans is encoded by the "DARC" gene. The Duffy antigen is located on the surface of red blood cells, and is named after the patient in which it was discovered. The protein encoded by this gene is a glycosylated membrane protein and a non-specific receptor for several chemokines. The protein is also the receptor for the human malarial parasites "Plasmodium vivax", "Plasmodium knowlesi" and simian malarial parasite "Plasmodium cynomolgi". Polymorphisms in this gene are the basis

title: Antigen-presenting cell

text: B cell marker CD40 binds to CD40L on the T cell surface. When activated by a T cell, a B cell can undergo antibody isotype switching, affinity maturation, as well as formation of memory cells. Non-professional antigen presenting cells include all nucleated cell types in the body. They use an MHC class I molecule coupled to beta-2 microglobulin to display endogenous peptides on the cell membrane. These peptides originate within the cell itself, in contrast to the exogenous antigen displayed by professional APCs using MHC class II molecules. Cytotoxic T cells are able to interact with endogenous antigen presented using

title: NS1 antigen test

text: NS1 antigen test NS1 antigen test (nonstructural protein 1), is a test for dengue, introduced in 2006. It allows rapid detection on the first day of fever, before antibodies appear some 5 or more days later. It has been adopted for use in some 40 nations. The method of detection is through enzyme-linked immunosorbent assay. India has introduced in 2010 the NS1 test costing 1,600 rupees at a private hospital in Mumbai. The medical use of the NS1 antigen test can be defined to diagnose dengue infections and is effective to 1st day detection. Additionally, NS1 assay is useful for

title: Prostate-specific antigen

text: of PSA in order to determine the origin of malignant cells that have metastasized. Prostate-specific antigen has been shown to interact with protein C inhibitor. Prostate-specific antigen Prostate-specific antigen (PSA), also known as gamma-seminoprotein or kallikrein-3 (KLK3), is a glycoprotein enzyme encoded in humans by the "KLK3" gene. PSA is a member of the kallikrein-related peptidase family and is secreted by the epithelial cells of the prostate gland. PSA is produced for the ejaculate, where it liquefies semen in the seminal coagulum and allows sperm to swim freely. It is also believed to be instrumental in dissolving cervical mucus, allowing

title: Middle tumor antigen

text: induce neoplastic transformation in some cells. The genes for the small tumor antigen (STag), middle tumor antigen (MTag), and large tumor antigen (LTag) are encoded in the "early region" of the polyomavirus genome, so named because this region of the genome is expressed early in the infectious process. (The "late region" contains genes encoding the viral capsid proteins.) In MTag-containing polyomaviruses, the early region contains at least three genes encoding STag, MTag, and LTag, and is transcribed as a single messenger RNA processed by alternative splicing. The LTag gene is usually encoded in two exons, of which the first overlaps

title: Diego antigen system

text: natives of New Britain, and Polynesians. Diego antigen system The Diego antigen (or blood group) system is composed of 21 blood factors or antigens carried on the Band 3 glycoprotein, also known as Anion Exchanger 1 (AE1). The antigens are inherited through various alleles of the gene SLC4A1 (Solute carrier family 4), located on human chromosome 17. The AE1 glycoprotein is expressed only in red blood cells and, in a shortened form, in some cells in the kidney. The Diego antigen is fairly common in Indigenous peoples of the Americas (in both North and South America) and East Asians, but

title: Diego antigen system

text: Diego antigen system The Diego antigen (or blood group) system is composed of 21 blood factors or antigens carried on the Band 3 glycoprotein, also known as Anion Exchanger 1 (AE1). The antigens are inherited through various alleles of the gene SLC4A1 (Solute carrier family 4), located on human chromosome 17. The AE1 glycoprotein is expressed only in red blood cells and, in a shortened form, in some cells in the kidney. The Diego antigen is fairly common in Indigenous peoples of the Americas (in both North and South America) and East Asians, but very rare or absent in most

title: Lewis antigen system

text: to detect the antigen Le-a. This is because the activity of the FUT2 enzyme is more efficient than the FUT3 enzyme, so the type I oligosaccharide chain is mostly converted into Le-b instead of Le-a. Therefore, people with readily detectable Lewis-a antigen are non-secretors; they do not have FUT2 activity. Lewis-b antigen is found only in secretors: people who possess the Se allele and thus have FUT2 activity. Lewis negative people (Le a-, Le b-) are homozygous for the recessive le allele and can be either secretors or non-secretors. Lewis antigens are expressed on the surface of red blood cells,

title: Small tumor antigen

text: effects independent of its PP2A-binding activity. MCPyV STag is believed to induce dysregulation of cap-dependent translation by promoting phosphorylation of eukaryotic translation initiation factor 4E-BP1. "In vivo" studies in rodent animal models suggest that MCPyV STag alone can be sufficient to drive transformation. Small tumor antigen The small tumor antigen (also called the small T-antigen and abbreviated STag or ST) is a protein encoded in the genomes of polyomaviruses, which are small double-stranded DNA viruses. STag is expressed early in the infectious cycle and is usually not essential for viral proliferation, though in most polyomaviruses it does improve replication efficiency.

title: Large tumor antigen

text: Large tumor antigen The large tumor antigen (also called the large T-antigen and abbreviated LTag or LT) is a protein encoded in the genomes of polyomaviruses, which are small double-stranded DNA viruses. LTag is expressed early in the infectious cycle and is essential for viral proliferation. Containing four well-conserved protein domains as well as several intrinsically disordered regions, LTag is a fairly large multifunctional protein; in most polyomaviruses, it ranges from around 600-800 amino acids in length. LTag has two primary functions, both related to replication of the viral genome: it unwinds the virus's DNA to prepare it for replication,

title: Chimeric antigen receptor

text: in incorporation of the artificial TCR into the native TCR, a factor that is dependent on the presence of the native CD3-zeta transmembrane charged aspartic acid residue. Different transmembrane domains result in different receptor stability. The CD28 transmembrane domain results in a highly expressed, stable receptor. This is the functional end of the receptor. After antigen recognition, receptors cluster and a signal is transmitted to the cell. The most commonly used endodomain component is CD3-zeta which contains 3 ITAMs. This transmits an activation signal to the T cell after the antigen is bound. CD3-zeta may not provide a fully competent

title: Chimeric antigen receptor

text: them, then infuse the resulting CAR-T cells into patients to attack their tumors. CAR-T cells can be either derived from T cells in a patient's own blood (autologous) or derived from the T cells of another healthy donor (allogenic). Once isolated from a person, these T cells are genetically engineered to express a specific CAR, which programs them to target an antigen that is present on the surface of tumors. For safety, CAR-T cells are engineered to be specific to an antigen expressed on a tumor that is not expressed on healthy cells. After CAR-T cells are infused into a

title: Kell antigen system

text: Kell antigen system The Kell antigen system (also known as Kell–Cellano system) is a group of antigens on the human red blood cell surface which are important determinants of blood type and are targets for autoimmune or alloimmune diseases which destroy red blood cells. Kell can be noted as K, k, or Kp. The Kell antigens are peptides found within the Kell protein, a 93-kilodalton transmembrane zinc-dependent endopeptidase which is responsible for cleaving endothelin-3. The "KEL" gene encodes a type II transmembrane glycoprotein that is the highly polymorphic Kell blood group antigen. The Kell glycoprotein links via a single disulfide

title: Duffy antigen system

text: not yet been identified. Biochemical analysis of the Duffy antigen has shown that it has a high content of α-helical secondary structure - typical of chemokine receptors. Its N-glycans are mostly of the triantennary complex type terminated with α2-3- and α2-6-linked sialic acid residues with bisecting GlcNAc and α1-6-linked fucose at the core. The Duffy antigen is expressed in greater quantities on reticulocytes than on mature erythrocytes. While the Duffy antigen is expressed on erythrocytes it is also found on some epithelial cells, Purkinje cells of the cerebellum, endothelial cells of thyroid capillaries, the post-capillary venules of some organs including

title: Lewis antigen system

text: no further modifications are made to the H antigen, the person is type O. When the A gene product acts on the H antigen and adds an N-acetylgalactosamine, the A antigen results and the person is type A. When the B gene product acts on the H antigen to add a galactose, the B antigen results and the person is type B. The Le gene encodes a fucosyltransferase that adds fucose to type 1 precursor substance (both free in serum and in secretions) to make the Le(a) antigen. The le gene is an amorph. The Lewis antigen produced on free

title: Fragment antigen-binding

text: Fragment antigen-binding The antigen-binding (Fab) fragment is a region on an antibody that binds to antigens. It is composed of one constant and one variable domain of each of the heavy and the light chain. The variable domain contains the paratope (the antigen-binding site), comprising a set of complementarity determining regions, at the amino terminal end of the monomer. Each arm of the Y thus binds an epitope on the antigen. In an experimental setting, Fc and Fab fragments can be generated in the laboratory. The enzyme papain can be used to cleave an immunoglobulin monomer into two Fab fragments

title: Fragment antigen-binding

text: the original specificity of the parent immunoglobulin. Fragment antigen-binding The antigen-binding (Fab) fragment is a region on an antibody that binds to antigens. It is composed of one constant and one variable domain of each of the heavy and the light chain. The variable domain contains the paratope (the antigen-binding site), comprising a set of complementarity determining regions, at the amino terminal end of the monomer. Each arm of the Y thus binds an epitope on the antigen. In an experimental setting, Fc and Fab fragments can be generated in the laboratory. The enzyme papain can be used to cleave

title: Rapid antigen test

text: Rapid antigen test A rapid antigen test (RAT) is a rapid diagnostic test suitable for point-of-care testing that directly detects the presence or absence of an antigen. This distinguishes it from other medical tests that detect antibodies (antibody tests) or nucleic acid (nucleic acid tests), of either laboratory or point of care types. Common examples of RATs or RADTs include: Antigen tests and antibody tests are often immunoassays (IAs) of one kind or another, such as dipstick IAs or fluorescence immunoassays. While RAT is an immunochromatographic assay which gives visual results that can be seen with naked eye. It is

title: Rapid antigen test

text: tests, although the particulars depend on which disease and which test are involved. Rapid antigen test A rapid antigen test (RAT) is a rapid diagnostic test suitable for point-of-care testing that directly detects the presence or absence of an antigen. This distinguishes it from other medical tests that detect antibodies (antibody tests) or nucleic acid (nucleic acid tests), of either laboratory or point of care types. Common examples of RATs or RADTs include: Antigen tests and antibody tests are often immunoassays (IAs) of one kind or another, such as dipstick IAs or fluorescence immunoassays. While RAT is an immunochromatographic assay

title: Duffy antigen system

text: the Duffy antigen found no differential resistance to malaria vivax between Duffy antigen positive and negative individuals. Nancy Ma's night monkey ("A. nancymaae") is used as an animal model of "P. vivax" infection. This species' erythrocytes possess the Duffy antigen and this antigen is used as the receptor for "P. vivax" on the erythrocytes in this species. Examination of this gene in 497 patients in the Amazonas State, Brazil, made by the doctor Sérgio Albuquerque, suggests that the genotypes FY*A/FY*B-33 and FY*B/FY*B-33 (where -33 refers to the null mutation at position -33 in the GATA box) may have an advantage

title: Diego antigen system

text: to the Diego family, but occurred in several populations in Venezuela and elsewhere in South America. Investigators suspected that the Diego factor might be a Mongoloid trait, and tested groups of Native Americans in the United States and people of Chinese and Japanese ancestry, and found Di in those groups. Anti-Di was found in 1967, establishing the Diego group as a two-antigen system. In 1993 the Diego pair of antigens was found to result from a single point mutation (nucleotide 2561) on what is now called the SLC4A1 gene on chromosome 17. The Wright antigen (Wr), a very low frequency

title: Antigen-antibody interaction

text: between a single binding site on an antibody and its target epitope is termed the affinity of that interaction. Avidity and affinity can be judged by the dissociation constant for the interactions they describe. The lower the dissociation constant, the higher the avidity or affinity, and the stronger the interaction. Antigen-antibody interaction is used in laboratory techniques for serological test of blood compatibility and various pathogenic infections. The most basic is ABO blood group determination, which is useful for blood transfusion. Sophisticated applications include ELISA, enzyme-linked immunospot (Elispot), immunofluorescence, and immunoelectrophoresis. Antigen-antibody interaction Antigen-antibody interaction, or antigen-antibody reaction, is a

title: Antigen-antibody interaction

text: has two paratopes, and in many circumstances complex binding occurs, the multiple binding equilibrium can be summed up as: where, at equilibrium, c is the concentration of free ligand, r represents the ratio of the concentration of bound ligand to total antibody concentration and n is the maximum number of binding sites per antibody molecule (the antibody valence). The overall strength of the binding of an antibody to an antigen is termed its avidity for that antigen. Since antibodies are bivalent or polyvalent, this is the sum of the strengths of individual antibody-antigen interactions. The strength of an individual interaction

title: Antigen

text: toward the antigens of the pathogen invading that recipient. Paul Ehrlich coined the term antibody (in German "Antikörper") in his side-chain theory at the end of the 19th century. In 1899, Ladislas Deutsch (Laszlo Detre) (1874–1939) named the hypothetical substances halfway between bacterial constituents and antibodies "substances immunogenes ou antigenes" (antigenic or immunogenic substances). He originally believed those substances to be precursors of antibodies, just as zymogen is a precursor of an enzyme. But, by 1903, he understood that an antigen induces the production of immune bodies (antibodies) and wrote that the word "antigen" is a contraction of antisomatogen ("Immunkörperbildner").

title: H-Y antigen

text: greater the inhibitory effect on brain masculinization, which is believed to be a factor in sexual orientation. This hypothesis is supported by evidence that older sisters have no discernible influence on the sexual orientation of later-born males, which would be expected since H-Y antigen is male tissue specific, the 'probable involvement of H-Y antigen in the development of sex-typical traits, and the detrimental effects of immunization of female mice to H-Y antigen on the reproductive performance of subsequent male offspring'. H-Y antigen H-Y antigen is a male tissue specific antigen. Originally thought to trigger the formation of testes (via loci,

title: Dharmendra antigen

text: from lepromatous leprosy. Dharmendra antigen The Dharmendra antigen is a test widely used in India. The antigen is a suspension of de-fatted leprosy bacilli which has been extracted with chloroform-ether and killed, either by heat, or by other effective methods. This antigen was first reported by Dharmendra in 1941–42 and later standardized in 1979 by Sangupta et al. Dharmendra's Lepromin suspension consists of 10 mg of the dried and de-fatted, bacillary powder, dissolved in 100 ml carbol saline solution. It is a revised form of the original Lepromin test developed in 1919 by Kensuke Mitsuda. The Dharmendra test allows to

title: Dharmendra antigen

text: Dharmendra antigen The Dharmendra antigen is a test widely used in India. The antigen is a suspension of de-fatted leprosy bacilli which has been extracted with chloroform-ether and killed, either by heat, or by other effective methods. This antigen was first reported by Dharmendra in 1941–42 and later standardized in 1979 by Sangupta et al. Dharmendra's Lepromin suspension consists of 10 mg of the dried and de-fatted, bacillary powder, dissolved in 100 ml carbol saline solution. It is a revised form of the original Lepromin test developed in 1919 by Kensuke Mitsuda. The Dharmendra test allows to differentiate tuberculoid leprosy

title: Antigen-antibody interaction

text: of Anthrax; Determination of adulteration in food. It acts on antigen-antibody reaction in which the antibodies cross-link particulate antigens resulting in the visible clumping of the particle. Use: Sereologic diagnosis of Enteric Fever. In an antibody, the Fab (fragment, antigen-binding) region is formed from the amino-terminal end of both the light and heavy chains of the immunoglobulin polypeptide. This region, called the variable (V) domain, is composed of amino acid sequences that define each type of antibody and their binding affinity to an antigen. The combined sequence of variable light chain (V) and variable heavy chain (V) creates three hypervariable

title: Diego antigen system

text: and in ethnic Indians (descended from southern Indians) to be a little under 1%. (A smaller sample of Malays in Penang, Malaysia, were 4% Di+.) The Di antigen is very rare in African and European populations. One West African subject had an ambiguous possible reaction to Di. About 0.5% of Europeans of Polish ancestry have been found to be Di+. Probably this incidence has been attributed to gene mixture from Tatars who invaded Poland five to seven centuries ago. Diego Antigen found in 0.89% of Germans from Berlin. The Di antigen is very rare or absent in Aboriginal Australians, Papuans,

title: Antigen transfer in the thymus

text: from the periphery to the thymus to mediate selection processes. "All these thymic DC subsets were shown to participate in antigen transfer". Nevertheless, only tDCs and mDCs were observed to utilize transferred TRAs for indirect presentation which led to the processes of central tolerance. The unambiguous mechanism of the antigen transfer is still unknown. However, there are three possible ways: I. "acquisition of mTEC apoptotic bodies", which could possibly be related with low mTEC lifespan II. "acquisition of exosomes" and III. "acquisition via trogocytosis", how antigen transfer can be mediated. There is also an evidence, that antigen transfer and therefore

title: Rapid antigen test

text: considered to be qualitative but an experience personal in RDT testing can easily quantify the results. Being a screening test, the results should be evaluated on the basis of confirmatory tests like PCR tesing or western blot. One inherent advantage of an antigen test over an antibody test (such as antibody-detecting rapid HIV tests) is that it can take time for the immune system to develop antibodies after infection begins, but the foreign antigen is present right away. Although any diagnostic test may have false negatives, this latency period can open an especially wide avenue for false negatives in antibody

title: Antigen-antibody interaction

text: on the interaction sites. Antigen and antibody interact through a high affinity binding much like lock and key. A dynamic equilibrium exists for the binding. For example, the reaction is a reversible one, and can be expressed as: where [Ab] is the antibody concentration and [Ag] is the antigen concentration, either in free ([Ab],[Ag]) or bound ([AbAg]) state. The equilibrium association constant can therefore be represented as: where "K" is the equilibrium constant. Reciprocally the dissociation constant will be: However, these equations are applicable only to a single epitope binding, i.e. one antigen on one antibody. Since the antibody necessarily

title: Dog leukocyte antigen

text: region two, this increases the risk of developing diabetes in dog as arginine is a positive amino acid which can impair antigen binding. This allele is also associated with hypothyroidism which implies that this allele increases susceptibility for endocrinopathic immune-mediated diseases. It is possible that the link discovered between DLA associations and diabetes could be due to "makers" of susceptibility and that the true reason for susceptibility lies elsewhere in the genome. It could be associated with particular DLA alleles/haplotypes or caused by the strong linkage disequilibrium. Dog leukocyte antigen The dog leukocyte antigen (DLA) is a part of the

title: Autologous patient-specific tumor antigen response

text: an immunoadjuvant, but also due to increases in antigen accessibility caused by the destruction of the tumor. Both elements of this protocol are crucial. Since this method independently triggers the immune response in each individual, it does not depend upon cross reactivity in the expression of tumor-specific antigen between hosts (as is required in conventional antibody immunotherapy and vaccination.) Veterinary Cancer Therapeutics, LLC, a subsidiary of IMULAN BioTherapeutics, LLC, is in exploratory trials for canine osteosarcoma, canine melanoma, canine and feline fibrosarcoma, and several other forms of cancer. Autologous patient-specific tumor antigen response Autologous patient-specific tumor antigen response (apSTAR) technology

title: Prostate-specific antigen

text: hyperplasia (BPH) and the commercial assay kits for PSA did not provide correct PSA values. The presence of inactive proenzyme forms of PSA is another potential indicator of disease. PSA exists in serum in the free (unbound) form and in a complex with alpha 1-antichymotrypsin; research has been conducted to see if measurements of complexed PSA are more specific and sensitive biomarkers for prostate cancer than other approaches. It is now clear that the term prostate-specific antigen is a misnomer: it is an antigen but is not specific to the prostate. Although present in large amounts in prostatic tissue and