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Results for “Major Histocompatibility Complex”

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At least 19 recordsLinked to original sources
PubMed1978

Major histocompatibility complex and non-major histocompatibility complex antigens on mouse ectoplacental cone and placental trophoblastic cells.

The expression of major histocompatibility complex and non-major histocompatibility complex antigens on mouse trophoblast cultured from two defined stages of development was investigated by the sensitive in vitro mixed haemadsorption assay. Outgrowths obtained 3 to 5 days after explanation of 7 1/2-day ectoplacental cones contained a mixed population of cells. Those with a giant cell morphology showed no haemadsorption with congenic H-2 antisera and were reactive with non H-2 antiserum only in the CBA strain. Other, smaller cells were reactive for both H-2 and non-H-2 in all strains examined except for C57BL, where the cells were nonreactive for H-2. Monolayer cultures of 13 to 14-day placental suspensions tested 24 hr after preparation were strongly reactive for both H-2 and non-H-2. The identity and alloantigenic status of the cells are discussed in relation to their function in maternal-foetal immunological interactions.

Animals↗
PubMed1991

Evolution of the major histocompatibility complex: molecular cloning of major histocompatibility complex class I from the amphibian Xenopus.

Class I major histocompatibility complex (MHC) cDNA clones have been isolated from an expression library derived from mRNA of an MHC homozygous Xenopus laevis. The nucleotide and predicted amino acid sequences show definite similarity to MHC class I molecules of higher vertebrates. The immunoglobulin-like alpha-3 domain is more similar to the immunoglobulin-like domains of mammalian class II beta chains than to those of mammalian class I molecules, and a tree based on nucleotide sequences of representative MHC genes is presented.

Amino Acid Sequence↗
PubMedDate not supplied

Rabbit major histocompatibility complex. IV. Expression of major histocompatibility complex class II genes.

The rabbit MHC class II DP, DQ, and DR alpha and beta chain genes were transfected into murine B lymphoma cells. The transfected cells expressed R-DQ and R-DR molecules on the cell surface but they did not express the R-DP genes either on the cell surface or at the level of mRNA. Northern blot analyses showed that the R-DP genes were expressed, albeit at low levels, in rabbit spleen. Similar analyses showed that the R-DQ and R-DR genes were expressed at high levels in rabbit spleen. A new monoclonal anti-rabbit class II antibody, RDR34, has been developed and shown to react with the R-DR transfected cells and not with the R-DQ transfected cells. The previously described monoclonal anti-rabbit class II antibody, 2C4, reacted with the R-DQ transfected cells and not with the R-DR transfected cells. Thus, 2C4 and RDR34 MAb's are specific for the R-DQ and R-DR molecules, respectively. Each of the antibodies reacted with approximately 50% of rabbit spleen cells as shown by immunofluorescent antibody studies.

Animals↗
PubMedDate not supplied

Complexity in the major histocompatibility complex.

The human major histocompatibility complex (MHC) is one of the most intensively studied regions of the human genome, containing over 70 known genes and spanning about 4 million base pairs (4 Mbp) of DNA on chromosome 6p21.3 (Klein, 1986). It can be divided up into three regions: the class I region (telomeric), the class II region (centromeric), and the class III region (between class I and II), which includes the complement component genes C2, C4, and Bf (Trowsdale & Campbell, 1988). The MHC has been mapped in detail using pulse field gel electrophoresis (PFGE) and by cloning in yeast artificial chromosome (YAC) and cosmid vectors, revealing long stretches of DNA between the regions as well as between individual class I and class II genes. Novel genes, that have no sequence relationships with class I, class II or complement components, have recently been found in these areas, and we will present an update on these after reviewing the more established loci.

Chromosome Mapping↗
PubMed1980

Structure and function of major histocompatibility complex.

The major histocompatibility complex (MHC) contains genes that control the structure of many important cell surface antigens and influence a variety of important biological functions. The structures of the MHC in the human, rat and mouse show a remarkable similarity both in terms of the location of their genes and the chemical structures of the gene products. Thus, the region of the chromosome containing the MHC has been highly conserved during evolution, and this finding suggests that its genes are important for survival. Another set of genes, which influences growth and development, is linked to the MHC in the mouse (T/t complex) and in the rat (Grc): this entire chromosomal region may function as a "supergene" with broad effects on tissue organization and compatibility.

Animals↗
PubMed1989

Genetic characterization of FLA, the cat major histocompatibility complex.

The major histocompatibility complex (MHC) of the domestic cat (termed FLA) has been refractile to genetic and serological definition largely because of repeated failure to detect cytotoxic antibodies in multiparous cats or to elicit antibody following allogeneic lymphocyte immunization. We have developed a protocol for producing cytotoxic alloantisera in the cat following rejection of multiple surgical skin grafts. Of 59 cats subjected to grafting, 13 produced lymphocytotoxic antisera which had varying specificities among a panel of outbred cat cells. A population cluster analysis of the 13 alloantisera permitted the identification of six clusters of overlapping FLA specificities. Serological analysis of cells from 12 cat kindreds led to the definition of 24 allogeneic haplotypes, which segregate as a single Mendelian complex. Feline FLA antisera were characterized as class I or class II specific by immunoprecipitation of FLA gene products on lymphocyte cell surfaces. Abundant antigenic polymorphisms for both class I and class II MHC determinants were discovered, a result consistent with precedence in other species and the common expectation of the adaptive value of MHC variation. Development of feline MHC typing reagents and the definition of haplotypes for the cat hold promise for experimental analysis of valuable feline models for virus-induced immune deficiencies.

Animals↗
PubMed1986

Evolution of the major histocompatibility complex.

The major histocompatibility complex is a group of closely linked loci that code for molecules used by T-lymphocytes as context for the recognition of antigens. The loci fall into two classes: I, coding for molecules used as context by cytotoxic T-lymphocytes and II, used as context by helper and other regulatory T-cells. The Mhc is present in all mammals and perhaps all vertebrates. Some of the Mhc loci are highly polymorphic, while others are not. This article will summarize what is known about the genetic organization of the Mhc in different species and will discuss the selection pressures acting on the individual loci and the tempo and the mechanisms of their evolution.

Animals↗
PubMedDate not supplied

The major histocompatibility complex.

The major histocompatibility complex on the sixth chromosome controls expression of a complex series of cell surface antigens which comprise the human leukocyte antigen (HLA) system. These markers, beyond their importance in human organ transplantation, have been demonstrated to occur with an increased prevalence in certain disease states. The group of conditions showing the closest association with specific HLA antigens are the "spondyloarthropathies." These include ankylosing spondylitis (AS), Reiter's syndrome (RS), psoriatic arthritis (PsA), and the arthritis of inflammatory bowel disease (AIBD). Clinical and radiographic studies were made of 310 unrelated caucasoid patients with seronegative arthritis. HLA-A, B, C, and DR typing were performed using the microdroplet lymphocyte cytotoxicity test. Statistically increased prevalences of A26, B27, and Bw38 were observed, while B27 was associated with spinal involvement regardless of diagnosis (90 percent in AS p less than 0.0001). Experiments found A26 (23 percent p less than 0.001) and Bw38 (38 percent p less than 0.0001) in patients with PsA. Spondyloarthritis patients with spinal involvement who lacked B27 frequently had B7. The HLA DR typing for seven specificities was carried out in 196 patients. It was found that DRw4 (52 percent p less than 0.03) and DRw7 (39 percent p less than 0.04) were increased in the PsA patients. This study further confirms the close association of HLA antigens and the spondylarthropathies.

Arthritis↗
PubMed1987

Persistence and selectivity of the immune phagocytosis inhibition by major histocompatibility complex antibodies.

Major histocompatibility complex (MHC) antibodies induce immune phagocytosis inhibition (IPI) which lasts for at least 7 days. IPI-inducing antibodies do not inhibit the phagocytosis mediated by the beta-glucan receptor. This corresponds well to recent findings that these antibodies do not interfere with the phagocytosis of deactivated saccharomyces, mediated by the mannose-fucose receptor, or polyacrylic acid particles, also mediated by non-Fc receptors. Substances that interact with certain MHC antigens or with Fc receptors, certain toxins that inhibit surface molecule mobility, and ciclosporin do not cause IPI and do not suppress the induction of IPI by MHC antibodies. These substances are: opioid peptides, insulin, penicillin G, immune complexes, aggregated IgG, Fc fragments, ciclosporin, botulinum C2 toxin, sodium azide. Some lectins and EDTA are inhibitory in a non-selective fashion, since the Fc receptor independent phagocytosis is also abrogated.

Antibodies, Monoclonal↗
PubMed1978

The unity of genes in the major histocompatibility complex.

The major histocompatibility complex (MHC) of the mouse can be genetically divided into several regions specialized to performing specific functions. Thus the class I regions (K and D) code for antigens that activate effector (killer) T cells, class II region (I) for antigens causing T-cell proliferation, and class III regions (s) for complement components. A strong case is made for the theory that the division of labor within the MHC is not absolute. Evidence is presented that class I antigens can sometimes cause as strong T-cell proliferation as class II antigens; that class II antigens can generate effector T cells; and that class I antigens may be involved in the immune response to some antigens. The fact that different regions can perform similar functions argues for the unity of the MHC genes.

Animals↗
PubMed1983

Specificity of T cell clones for antigen and autologous major histocompatibility complex products determines specificity for foreign major histocompatibility complex products.

We have analyzed a panel of T cell clones that corecognize defined epitopes of the insulin molecule in association with Ia for their patterns of recognition of alloantigens. A striking correlation is observed between recognition of the I-Ab gene product and cow insulin alpha loop and recognition of I-Eu of the PL/J haplotype. These results are consistent with the notion that reactions to foreign major histocompatibility complex (MHC) products reflect molecular mimicry by foreign class II antigens of 'physiologic' complexes formed by autologous class II MHC molecules and antigen.

Animals↗
PubMed1987

Aberrant expression of class II major histocompatibility complex molecules by B cells and hyperexpression of class I major histocompatibility complex molecules by insulin containing islets in type 1 (insulin-dependent) diabetes mellitus.

Twenty-three patients with recent onset Type 1 (insulin-dependent) diabetes in whom residual insulin secreting B cells were present and 12 patients with disease of more prolonged duration (maximum 9 years), 8 of whom had residual B cells, were studied. Aberrant expression of Class II major histocompatibility complex molecules was demonstrated immunohistochemically on insulin secreting B cells in 21 out of 23 patients with recent onset disease and 6 of the patients with more prolonged disease. No such expression was seen on glucagon secreting A cells or somatostatin secreting D cells. Islets where there was marked hyperexpression of Class I major histocompatibility complex molecules on islet endocrine cells were seen in all cases in which residual B cells were present. Ninety-two per cent of insulin containing islets but only 1% of insulin deficient islets exhibited this phenomenon (p less than 0.001, Chi-squared test). There was evidence to suggest that both these abnormalities of major histocompatibility complex expression preceded insulitis within a given islet. They also appeared to be unique to Type 1 diabetes, being absent in pancreases of patients with Type 2 (non-insulin-dependent) diabetes, chronic pancreatitis, cystic fibrosis, graft-versus-host disease and Coxsackie B viral pancreatitis. The development of autoimmunity to B cells in Type 1 diabetes may be a "multistep" process in which abnormalities of major histocompatibility complex expression on islet endocrine cells are crucial events.

Adolescent↗
PubMed1989

Embryonal carcinoma cells express Qa and Tla class I genes of the major histocompatibility complex.

The murine major histocompatibility complex encodes H-2K and H-2D transplantation antigens and other class I-like proteins called Qa and Tla molecules; the functions of the Qa/Tla molecules are not known. That they may participate in embryonic cell-cell interactions and/or play a role in immune responses against tumors has been speculated. We have studied two murine embryonal carcinoma tumors, 402AX and PCC4, that are rejected in vivo immunologically, although they do not express H-2K or H-2D antigens. Transplantation studies with these cells suggest that rejection is mediated by class-I-like major histocompatibility complex antigens. As a first step in evaluating Qa/Tla function(s), we have characterized expression of class I-like genes and proteins in 402AX and PCC4 cells. Northern (RNA) blot hybridizations, polymerase chain reaction studies, and cDNA cloning experiments demonstrate that EC lines transcribe genes allelic to the Tla region gene "37", Qa-2 region gene "Q7", and another, previously uncharacterized, class I-like gene. Immunoprecipitation studies show that the embryonal carcinoma tumor cells contain low levels of beta 2-microglobulin expressed in association with non-H-2K, non-H-2D class I-like proteins.

Amino Acid Sequence↗
PubMed1983

Evidence for extensive polymorphism of class I genes in the rat major histocompatibility complex (RT1).

The major histocompatibility complex of the rat (RT1) has been poorly characterized with respect to the number, linkage, and polymorphism of class I genes. To estimate the number of class I RT1 genes and the relative extent of their polymorphism, we performed Southern blot analysis with liver DNA from rat strains expressing eight RT1 haplotypes. After digestion with EcoRI and BamHI, the DNA was separated on agarose gels, blotted onto nitrocellulose, and hybridized with mouse H-2 cDNA probes, pH-2III and pH-2IIa. Ten to 20 EcoRI and 13 to 20 BamHI bands hybridized with pH-2III and pH-2IIa; restriction fragment length patterns were observed to be highly polymorphic. The restriction fragments associated with different RT1 haplotypes differed by 17-70%; this range is similar to the differences observed between mouse H-2 haplotypes. The same restriction fragment pattern was observed in DNA from three different rat strains sharing the same RT1 allele, confirming that the patterns were RT1-associated. Further, the RT1l and RT1lvl haplotypes, which differ at a single previously identified RT1-linked locus, were associated with EcoRI restriction pattern differences of 39-50%, confirming the supposition that RT1 class I genes identified by previous serological and T-cell-mediated assays have identified only a minority of the actual number of RT1-linked class I genes. In summary, the results reported in this communication demonstrate that the RT1 complex encompasses a large family of highly polymorphic class I genes similar to the H-2 and HL-A complexes of mouse and man.

Alleles↗
PubMed1986

Genes for the tumor necrosis factors alpha and beta are linked to the human major histocompatibility complex.

The human major histocompatibility complex (MHC) includes the closely linked genes for the tumor necrosis factors alpha and beta. Their location is within the chromosomal segment between HLA-DR and HLA-A or centromeric of HLA-DP. This assignment is based on Southern blot analysis of a number of different MHC deletion mutants and is corroborated by chromosome in situ hybridization.

Chromosome Deletion↗
PubMed1987

Subregions and functions of the chicken major histocompatibility complex.

The chicken major histocompatibility complex (MHC) exerts genetic influence over a variety of important biological functions including immune response, disease resistance, growth and development, aging, and reproduction. The chicken MHC possesses at least three subregions encoding distinct gene products. The B-G subregion encodes antigens unique to erythrocyte surfaces. The B-L and B-F subregions encode cell surface glycoproteins homologous to mammalian Class II and Class I antigens, respectively. Class I and Class II molecules are crucial for recognition of self vs. nonself and for cell communication, and therefore are fundamental for all immune responses. Studies of chromosomal recombinants have been particularly useful in eliciting the structure and function of subregions of the chicken MHC.

Animals↗
PubMed1992

Genes, genes and more genes in the human major histocompatibility complex.

The human major histocompatibility complex (MHC), on the short arm of chromosome 6, represents one of the most extensively characterised regions of the human genome. This approximately 4 Mb segment of DNA contains genes encoding the polymorphic MHC class I and class II molecules which are involved in antigen presentation during an immune response. Recently the whole of the MHC has been cloned in cosmids and/or yeast artificial chromosomes (YACs) and large portions have been characterised for the presence of novel genes. Many unrelated genes, both housekeeping and tissue specific, have been identified and the gene density in some regions is now approaching one gene every few kilobases. Some of the novel genes encode proteins involved in the intracellular processing and transport of antigens that are presented by MHC class I molecules. Others, however, have no obvious role in the immune response. The MHC is located in the chromosome band 6p21.3 which is a Giemsa (G)-light band. The detection of such a large number of functional genes (at least 70) in this region is compatible with the idea that both housekeeping and tissue-specific genes are localised predominantly in G-light bands.

Chromosome Mapping↗
PubMed1991

Reactions of the subunits of the class II major histocompatibility complex molecule IAd.

Major histocompatibility complex (MHC) class II molecules are heterodimers formed by noncovalent linkage of alpha and beta chains. It has been shown that the subunits of the MHC class II molecules IAd and IEk bind antigenic peptides as well as antigenic peptides labeled with fluorescent probes. Laser scanning fluorescence microscopy on SDS/polyacrylamide gels demonstrates that the subunit-peptide complexes of IAd are stable over a wide pH range. Below pH 5.3 the heterodimer of IAd dissociates into the free chains, which still bind antigenic peptides such as the 18-amino acid peptide obtained by a tyrosine addition to a chicken ovalbumin peptide, Ova-(323-339)Y. The stability of preformed subunit complexes with fluorescein-labeled Ova-(323-339)Y was investigated by using high-performance size exclusion chromatography and epifluorescence microscopy. Each subunit forms a long-lived complex, both in detergent solutions and in reconstituted lipid bilayers. At 37 degrees C and pH 7.0 the dissociation half-time of the beta-subunit-peptide complex was determined to be 28 hr and that of the alpha-subunit-peptide complex was 10 hr. In contrast to the dissociation of the peptide from the IAd heterodimer, the half-times for dissociation of the peptide from the separate chains are not decreased at pH 5.0.

Animals↗