major histocompatibility complex
a group of genes that control the expression of cell surface protein markers (also known as human leukocyte antigen or HLA markers) that determine receptor shape and allow immune cells to recognize components of the body (i.e., to distinguish "self" from "non-self"). MHC molecules are necessary for antigen presentation and for recognition of antigens by immune system cells. Each individual has one of a variety of genetically-determined MHC/HLA patterns. There are two classes of MHC molecules, MHC-I and MHC-II. | ||||
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Major histocompatibility complex Definition from Medicine Dictionaries & Glossaries
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MAJOR HISTOCOMPATIBILITY COMPLEX
Two classes of molecules on cell surfaces. MHC class I molecules exist on all cells, and hold and present foreign antigens<!-- (see) --> to CD8 cytotoxic T lymphocytes<!-- (see) --> if the cell is infected by a virus or other microbe. MHC class II molecules are the billboards of the immune system. Peptides derived from foreign proteins are inserted into MHC's binding groove and displayed on the surface of antigen-presenting cells. These peptides are then recognized by T lymphocytes so that the immune system is alerted to the presence of foreign material. See Histocompatibility Testing.
Two classes of molecules on cell surfaces. MHC class I molecules exist on all cells, and hold and present foreign antigens<!-- (see) --> to CD8 cytotoxic T lymphocytes<!-- (see) --> if the cell is infected by a virus or other microbe. MHC class II molecules are the billboards of the immune system. Peptides derived from foreign proteins are inserted into MHC's binding groove and displayed on the surface of antigen-presenting cells. These peptides are then recognized by T lymphocytes so that the immune system is alerted to the presence of foreign material. See Histocompatibility Testing.
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MHC
the gene cluster that controls certain aspects of the immune response. Among the products of these genes are the histocompatibility antigens, such as HLA class I antigens, which are present on every cell with a nucleus and serve as markers to distinguish self from non-self. (See also HLA.)
the gene cluster that controls certain aspects of the immune response. Among the products of these genes are the histocompatibility antigens, such as HLA class I antigens, which are present on every cell with a nucleus and serve as markers to distinguish self from non-self. (See also HLA.)
Major histocompatibility complex Definition from Science & Technology Dictionaries & Glossaries
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Major Histocompatibility Complex
(MHC): A genetic complex of vertebrates consisting of around 100 genes including the extremely polymorphic cell surface molecules called HLA in humans and H-2 in mice. These molecules provide an immunological marker for selfness and a genetic self-identity to the individual. This information is used in mate choice, union of gametes, maintenance of pregnancy, and immune response against nonself (including a transplanted graft). These molecules are the most polymorphic ones in vertebrates. The polymorphism arises from point mutations not at an unusually higher rate than other genes, and mainly from interallelic gene conversion events. The polymorphism is maintained through pathogen and non-pathogen driven mechanisms via heterozygous advantage (overdominant selection) and negative frequency dependent selection. A 3.6 Mb long human MHC haplotype and the 92 kb chicken MHC have been totally sequenced (see Nature 1999(Oct 28);401:921-925).
(MHC): A genetic complex of vertebrates consisting of around 100 genes including the extremely polymorphic cell surface molecules called HLA in humans and H-2 in mice. These molecules provide an immunological marker for selfness and a genetic self-identity to the individual. This information is used in mate choice, union of gametes, maintenance of pregnancy, and immune response against nonself (including a transplanted graft). These molecules are the most polymorphic ones in vertebrates. The polymorphism arises from point mutations not at an unusually higher rate than other genes, and mainly from interallelic gene conversion events. The polymorphism is maintained through pathogen and non-pathogen driven mechanisms via heterozygous advantage (overdominant selection) and negative frequency dependent selection. A 3.6 Mb long human MHC haplotype and the 92 kb chicken MHC have been totally sequenced (see Nature 1999(Oct 28);401:921-925).
Major histocompatibility complex Definition from Encyclopedia Dictionaries & Glossaries
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Major histocompatibility complex
The major histocompatibility complex (MHC) is a large genomic region or gene family found in most vertebrates. It is the most gene-dense region of the mammalian genome and plays an important role in the immune system, autoimmunity, and reproductive success. The proteins encoded by the MHC are expressed on the surface of cells in all jawed vertebrates, and display both self antigens (peptide fragments from the cell itself) and nonself antigens (e.g. fragments of invading microorganisms) to a type of white blood cell called a T cell that has the capacity to kill or co-ordinate the killing of pathogens, infected or malfunctioning cells.
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