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see transplantation, medicaltransplantation, medical,
surgical procedure by which a tissue or organ is removed and replaced by a corresponding part, usually from another part of the body or from another individual.
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A term used to describe the genes that influence acceptance or rejection of grafts. When grafts of tissue are exchanged between genetically dissimilar individuals, profound immunological rejection generally takes place. In contrast, grafts between genetically similar individuals, such as identical twins, are normally tolerated; they are histocompatible. Most known examples of histocompatibility (or H) genes encode polymorphic (that is, tending to differ between individuals) cell-surface proteins.

The major histocompatibility complex (MHC) contains a set of histocompatibility genes, termed major because mismatching at these genes invokes rapid rejection. The main function of MHC genes involves distinguishing self from nonself in the immune system, as part of preventing the spread of infectious disease. The body employs special mechanisms to avoid rejection of the fetus, which is effectively an allograft, that is, a graft from a donor to a genetically dissimilar recipient of the same species; in this case, the mechanisms include a diminution of MHC gene expression.

The MHC contains a spectrum of genes, many of which influence processing and presentation of antigens to the immune system. In mice, the MHC is designated the H-2 complex; in humans, it is referred to as the HLA complex (for human leukocyte A system). Mice and other mammals seem to have a similar arrangement of genes in their MHCs. See Antigen, Cellular immunology, Mendelism, Transplantation biology

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.


The capacity to accept or reject a tissue graft.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Molecular genetics of the swine major histocompatibility complex, the SLA complex.
Following the discovery of the first histocompatibility antigen "MAC" in 1958, numerous independent laboratories began identifying HLA specificities with alloantibodies.
Key words: Major histocompatibility complex (MHC); cDNA; genomic structure; polymorphism; swamp eel(Monopterus albus).
A mean for a comprehensive measure of histocompatibility can in the context of the extensive polymorphism only take place as a systematic study of key alleles with distinct polymorphism.
The study is not the first to implicate the major histocompatibility complex (MHC), a cluster of genes critical to the recognition of the body's own cells as "self," but it is the largest and most definitive, and its findings call into question data from smaller studies that suggested critical roles for other genetic regions.
SAN DIEGO -- A very large genetic linkage study has pinpointed the major histocompatibility complex on the short arm of chromosome 6 as the key genetic player in multiple sclerosis.
This is accomplished by selecting cells that express a known marker, such as proteins expressed by genes encoding the major histocompatibility complex.
This technique requires that whole proteins or selected peptide antigens are added to blood cells, allowing the simultaneous analysis of both major histocompatibility complex class I and II restricted T-cell responses (7).
This antibody binds to certain cell surface receptors, the so-called MHC (major histocompatibility complex) class II molecules, killing activated, proliferating MHC class II positive tumor cells, including B-cell- and T-cell-lymphomas and others.
Furthermore, a Major Histocompatibility Complex (MHC)-class-I-restricted T cell activation ELISPOT assay showed elevated interferon- [gamma], interleukin-2, and interleukin-12 production in HA/SHIV 89.6 VLP-immunized mice, indicating that phenotypically mixed HA/SHIV 89.6 VLPs can enhance both humoral and cellular immune responses at multiple mucosal sites.
The purpose of this project is to examine the DRB region of the major histocompatibility complex (MHC) in the owl monkey (Aotus azarai).
The major histocompatibility complex (MHC) or Histocompatibility-2 (H-2) complex is lobated within the seventeenth chromosome of mice.