Expression of a microinjected porcine class I major histocompatibility complex gene in transgenic mice

A porcine class I major histocompatibility complex (SLA) gene has been introduced into the genome of a C57BL/10 mouse. This transgenic mouse expressed SLA antigen on its cell surfaces and transmitted the gene to offspring, in which the gene is also expressed. Skin grafts of such transgenic mice were rejected by normal C57BL/10 mice, suggesting that the foreign SLA antigen expressed in the transgenic mice is recognized as a functional transplantation antigen.     

Presentation of exogenous antigen with class I major histocompatibility complex molecules

Soluble antigens (Ags) in the extracellular fluids are excluded from the class I major histocompatibility complex (MHC)-restricted pathway of Ag presentation in most cells. However, an exogenous Ag can be internalized, processed, and presented in association with class I MHC molecules on specialized Ag-presenting cells (APCs). These APCs express class II molecules and can simultaneously present exogenous Ags to both class I and class II MHC-restricted T cells. These APCs may be important participants in the regulation of host immune responses. This APC activity may explain several phenomena of cytotoxic T lymphocyte (CTL) priming in vivo and might be exploited for eliciting CTL responses to protein vaccines.     

Viral persistence in neurons explained by lack of major histocompatibility class I expression

Viruses frequently persist in neurons, suggesting that these cells can evade immune surveillance. In a mouse model, 5 x 10(6) cytotoxic T lymphocytes (CTLs), specific for lymphocytic choriomeningitis virus (LCMV), did not lyse infected neurons or cause immunopathologic injury. In contrast, intracerebral injection of less than 10(3) CTL caused disease and death when viral antigens were expressed on leptomeningeal and choroid plexus cells of the nervous system. The neuronal cell line OBL21 expresses little or no major histocompatibility (MHC) class I surface glycoproteins and when infected with LCMV, resisted lysis by virus-specific CTLs. Expression of MHC heavy chain messenger RNA was limited, but beta 2-microglobulin messenger RNA and protein was made normally. OBL21 cells were made sensitive to CTL lysis by transfection with a fusion gene encoding another MHC class I molecule. Hence, neuronal cells probably evade immune surveillance by failing to express MHC class I molecules.     

The NOD mouse: recessive diabetogenic gene in the major histocompatibility complex

Examination of the histocompatibility region of the nonobese diabetic (NOD) mouse with antibodies against class II glycoproteins (products of immune response genes of the major histocompatibility complex I-A and I-E), hybrid T-cell clones, and mixed-lymphocyte cultures and analysis of restriction fragment length polymorphisms indicate that the NOD mouse has a unique class II major histocompatibility complex with no expression of surface I-E, no messenger RNA for I-E alpha, and an I-A not recognized by any monoclonal antibodies or hybrid T-cell clones studied. In crosses of NOD mice with control C3H mice, the development of diabetes was dependent on homozygosity for the NOD mouse's unique major histocompatibility region.     

Depletion of CD4+ T cells in major histocompatibility complex class II-deficient mice

The maturation of T cells in the thymus is dependent on the expression of major histocompatibility complex (MHC) molecules. By disruption of the MHC class II Ab beta gene in embryonic stem cells, mice were generated that lack cell surface expression of class II molecules. These MHC class II-deficient mice were depleted of mature CD4+ T cells and were deficient in cell-mediated immune responses. These results provide genetic evidence that class II molecules are required for the maturation and function of mature CD4+ T cells.     

Genes of the major histocompatibility complex in mouse and man

The genes of the major histocompatibility complex code for cell-surface molecules that play an important role in the generation of the immune response. These genes and molecules have been studied intensively over the last five decades by geneticists, biochemists, and immunologists, but only recently has the isolation of the genes by molecular biologists facilitated their precise characterization. Many surprising findings have been made concerning their structure, multiplicity, organization, function, and evolution.     

Molecular analysis of the hotspot of recombination in the murine major histocompatibility complex

Biological and serological assays have been used to define four subregions for the I region of the major histocompatibility complex (MHC) in the order I-A, I-B, I-J, and I-E. The I-J subregion presumably encodes the I-J polypeptide of the elusive T-cell suppressor factors. Restriction enzyme site polymorphisms and DNA sequence analyses of the I region from four recombinant mouse strains were used to localize the putative I-B and I-J subregions to a 1.0-kilobase (kb) region within the E beta gene. Sequencing this region from E beta clones derived from the two mouse strains: B10.A(3R), I-Jb and B10.A(5R), I-Jk initially used to define the I-J subregion revealed that these regions are identical, hence the distinct I-Jb and I-Jk molecules cannot be encoded by this DNA. In addition, the DNA sequence data also refute the earlier mapping of the I-B subregion. Analysis of the DNA sequences of three parental and four I region recombinants reveals that the recombinant events in three of the recombinant strains occurred within a 1-kb region of DNA, supporting the proposition that a hotspot for recombination exists in the I region. The only striking feature of this hotspot is a tetramer repeat (AGGC)n that shows 80 percent homology to the minisatellite sequence which may facilitate recombination in human chromosomes.     

鱼类主要组织相容性复合体研究现状与展望

主要组织相容性复合体 (ｍａｊｏｒｈｉｓｔｏｃｏｍｐａｔｉｂｉｌｉｔｙｃｏｍｐｌｅｘ ,ＭＨＣ)是指染色体上由一系列紧密连锁的基因位点所组成的具有高度多态性的复合遗传系统或区域[1 ] 。ＭＨＣ广泛参与免疫应答的诱导与调节 ,激发机体特异性免疫反应 ,在免疫学上具有极为重要的意义。在鱼类 ,ＭＨＣ研究刚刚开始。1　哺乳动物的ＭＨＣ目前对人和小鼠的ＭＨＣ有较详细的研究[1 ] 。 1 999年人类的ＭＨＣ基因组测序工作已经全部完成[2 ] 。人类ＭＨＣ又称ＨＬＡ(ＨｕｍａｎＬｅｕｋｏｃｙｔｅＡｎｔｉｇｅｎ ,人类白细胞抗原 ) ,定位在…     

鱼类主要组织相容性复合体研究现状与展望

主要组织相容性复合体 (ｍａｊｏｒｈｉｓｔｏｃｏｍｐａｔｉｂｉｌｉｔｙｃｏｍｐｌｅｘ ,ＭＨＣ)是指染色体上由一系列紧密连锁的基因位点所组成的具有高度多态性的复合遗传系统或区域[1 ] 。ＭＨＣ广泛参与免疫应答的诱导与调节 ,激发机体特异性免疫反应 ,在免疫学上具有极为重要的意义。在鱼类 ,ＭＨＣ研究刚刚开始。1　哺乳动物的ＭＨＣ目前对人和小鼠的ＭＨＣ有较详细的研究[1 ] 。 1 999年人类的ＭＨＣ基因组测序工作已经全部完成[2 ] 。人类ＭＨＣ又称ＨＬＡ(ＨｕｍａｎＬｅｕｋｏｃｙｔｅＡｎｔｉｇｅｎ ,人类白细胞抗原 ) ,定位在…     

Influence of the major histocompatibility complex on positive thymic selection of V beta 17a+ T cells

A monoclonal antibody was used to show directly positive thymic selection of the T cell repertoire in mouse strains expressing the 17a beta-chain variable domain (V beta 17a) of the T cell receptor. In the absence of the potent tolerizing class II major histocompatibility complex (MHC) molecule, I-E, peripheral expression of V beta 17a+ T cell receptors varied with the MHC haplotype of the mouse strain. In the most extreme case, H-2q mice expressed high peripheral levels of CD4+ V beta 17a+ T cells (14 to 19 percent), whereas H-2b mice expressed low levels (3 to 4 percent). Analysis of (b x q)F1 mice and chimeric mice showed that these differences were determined by positive thymic selection and implicated the thymic epithelium as the controlling cell type.     

Molecular biology of the H-2 histocompatibility complex

The H-2 histocompatibility complex of the mouse is a multigene family, some members of which are essential for the immune response to foreign antigens. The structure and organization of these genes have been established by molecular cloning, and their regulation and function is being defined by expression of the cloned genes.     

The relation between major histocompatibility complex (MHC) restriction and the capacity of Ia to bind immunogenic peptides

The capacity of purified I-Ad, I-Ed, I-Ak, and I-Ek to bind to protein derived peptides that have been previously reported to be T cell immunogens has been examined. For each of the 12 peptides studied strong binding to the relevant Ia restriction element was observed. All the peptides bound more than one Ia molecule; however, for 11 of 12 peptides, the dominant binding was to the restriction element, whereas in one instance the dominant binding was to a nonrestriction element. When the peptides were used to inhibit the presentation of antigen by prefixed accessory cells to T cells, an excellent correlation was found between the capacity of a peptide to inhibit the binding of an antigen to purified Ia and the capacity of the peptide to inhibit accessory cell presentation of the antigen. Thus, the binding of peptide to purified Ia is immunologically relevant, and Ia seems to be the only saturable molecule on the surface of the accessory cell involved in antigen presentation. Inhibition analysis also indicated that all peptides restricted to a particular Ia molecule competitively inhibited one another, suggesting that each Ia restriction element has a single binding site for antigen. Cross-linking of labeled peptides to Ia followed by electrophoretic analysis and autoradiography suggested that this single binding site is made up of portions of both alpha and beta chains of Ia.     

Genetic and immunological complexity of major histocompatibility regions

There are genetic differences within the major histocompatibility complex of the mouse which lead to skin graft rejection but which cannot be detected serologically. When confronted with these differences on allogeneic cells, lymphocytes proliferate in vitro. In other cases, in vitro lymphocyte proliferation but no skin graft rejection is associated with loci that are linked to but genetically separable from the loci controlling the serologically defined antigens.     

乙醇脱氢酶I类基因全长cDNA的克隆与表达

I类乙醇脱氢酶（ADH）在乙醇的肝代谢中发挥重要作用，由ADHl，ADH2和ADH3组成。根据序列数据设计一对引物，利用RT—PCR同时克隆乙醇脱氢酶I类基因全长eDNA。测序后的eDNA被克隆在表达载体pTYBll上并在大肠杆菌中稳定表达。纯化获得的酶通过其在340nm处吸光值的变化进行酶活性测定。经检测重组ADHl，ADH2和ADH3的酶活力分别为2．0±0．3，0．8±0．2，1．5±0．2U·mg^-1。     

The major genetic determinants of HIV-1 control affect HLA class I peptide presentation

Infectious and inflammatory diseases have repeatedly shown strong genetic associations within the major histocompatibility complex (MHC); however, the basis for these associations remains elusive. To define host genetic effects on the outcome of a chronic viral infection, we performed genome-wide association analysis in a multiethnic cohort of HIV-1 controllers and progressors, and we analyzed the effects of individual amino acids within the classical human leukocyte antigen (HLA) proteins. We identified >300 genome-wide significant single-nucleotide polymorphisms (SNPs) within the MHC and none elsewhere. Specific amino acids in the HLA-B peptide binding groove, as well as an independent HLA-C effect, explain the SNP associations and reconcile both protective and risk HLA alleles. These results implicate the nature of the HLA-viral peptide interaction as the major factor modulating durable control of HIV infection.     

兔支气管败血性波氏杆菌fimN基因的原核表达

应用PCR方法扩增兔支气管波氏杆菌(Bb)的菌毛蛋白基因( fimN),将fimN基因克隆到表达载体pET-28a(+)中,获得重组质粒pET28a-fimN。将此重组质粒转化受体菌BL21后,用IPTG进行诱导表达,SDS-PAGE结果显示表达蛋白分子量大小约为27 kD,与理论预期值相符。用Western-blot试验分析纯化的表达产物,结果表明,该重组蛋白能与Bb阳性血清发生特异性反应。     

Defective presentation of endogenous antigen by a cell line expressing class I molecules

Cytotoxic T lymphocytes (CTLs) recognize class I major histocompatibility complex (MHC) molecules associated with antigenic peptides derived from endogenously synthesized proteins. Binding to such peptides is a requirement for class I assembly in the endoplasmic reticulum (ER). A mutant human cell line, T2, assembles and transports to its surface some, but not all, class I MHC molecules. The class I molecules expressed on the surface of T2 do not present peptides derived from cytosolic antigens, although they can present exogenously added peptides to CTL. The transported class I molecules may interact weakly with an unknown retaining factor in the ER such that they can assemble despite the relative shortage of peptides.