Glycolipid antigen processing for presentation by CD1d molecules

The requirement for processing glycolipid antigens in T cell recognition was examined with mouse CD1d-mediated responses to glycosphingolipids (GSLs). Although some disaccharide GSL antigens can be recognized without processing, the responses to three other antigens, including the disaccharide GSL Gal(alpha1-->2)GalCer (Gal, galactose; GalCer, galactosylceramide), required removal of the terminal sugars to permit interaction with the T cell receptor. A lysosomal enzyme, alpha-galactosidase A, was responsible for the processing of Gal(alpha1-->2)GalCer to generate the antigenic monosaccharide epitope. These data demonstrate a carbohydrate antigen processing system analogous to that used for peptides and an ability of T cells to recognize processed fragments of complex glycolipids.     

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.     

Expression of interleukin-10 activity by Epstein-Barr virus protein BCRF1

Cytokine synthesis inhibitory factor (CSIF; interleukin-10), a product of mouse TH2 T cell clones that inhibits synthesis of cytokines by mouse TH1 T cell clones, exhibits extensive sequence similarity to an uncharacterized open reading frame in the Epstein-Barr virus BCRF1. Recombinant BCRF1 protein mimics the activity of interleukin-10, suggesting that BCRF1 may have a role in the interaction of the virus with the host's immune system.     

Leucine-tRNA initiates at CUG start codons for protein synthesis and presentation by MHC class I

Effective immune surveillance by cytotoxic T cells requires newly synthesized polypeptides for presentation by major histocompatibility complex (MHC) class I molecules. These polypeptides are produced not only from conventional AUG-initiated, but also from cryptic non-AUG-initiated, reading frames by distinct translational mechanisms. Biochemical analysis of ribosomal initiation complexes at CUG versus AUG initiation codons revealed that cells use an elongator leucine-bound transfer RNA (Leu-tRNA) to initiate translation at cryptic CUG start codons. CUG/Leu-tRNA initiation was independent of the canonical initiator tRNA (AUG/Met-tRNA(i)(Met)) pathway but required expression of eukaryotic initiation factor 2A. Thus, a tRNA-based translation initiation mechanism allows non-AUG-initiated protein synthesis and supplies peptides for presentation by MHC class I molecules.     

Asymmetric segregation of polarized antigen on B cell division shapes presentation capacity

During the activation of humoral immune responses, B cells acquire antigen for subsequent presentation to cognate T cells. Here we show that after mouse B cells accumulate antigen, it is maintained in a polarized distribution for extended periods in vivo. Using high-throughput imaging flow cytometry, we observed that this polarization is preserved during B cell division, promoting asymmetric antigen segregation among progeny. Antigen inheritance correlates with the ability of progeny to activate T cells: Daughter cells receiving larger antigen stores exhibit a prolonged capacity to present antigen, which renders them more effective in competing for T cell help. The generation of progeny with differential capacities for antigen presentation may have implications for somatic hypermutation and class switching during affinity maturation and as B cells commit to effector cell fates.     

Assistance of microbial glycolipid antigen processing by CD1e

Complexes between CD1 molecules and self or microbial glycolipids represent important immunogenic ligands for specific subsets of T cells. However, the function of one of the CD1 family members, CD1e, has yet to be determined. Here, we show that the mycobacterial antigens hexamannosylated phosphatidyl-myo-inositols (PIM6) stimulate CD1b-restricted T cells only after partial digestion of the oligomannose moiety by lysosomal alpha-mannosidase and that soluble CD1e is required for this processing. Furthermore, recombinant CD1e was able to bind glycolipids and assist in the digestion of PIM6. We propose that, through this form of glycolipid editing, CD1e helps expand the repertoire of glycolipidic T cell antigens to optimize antimicrobial immune responses.     

Long-term high-titer neutralizing activity induced by octameric synthetic HIV-1 antigen

A titer for homologous viral neutralization activity (greater than 1:19,683) was observed after a 3.5-year immunization period with an octameric, branching peptide representing the principal neutralizing determinant (PND) of the human immunodeficiency virus-1IIIB envelope protein. Booster immunizations elicited persistent and potent antibodies in guinea pigs, exceeding responses produced by a conventional bovine serum albumin conjugate by 100-fold. Peptide length, central presentation of a conserved sequence, and inclusion of an upstream sequence contributed to immunogenicity. Titers (greater than 1:1,000) of heterotypic neutralizing antibodies also developed. Octameric PND peptides are a promising approach for an acquired immunodeficiency syndrome (AIDS) vaccine.     

伏马菌素B_1人工抗原的构建

碳化二亚胺法将伏马菌素B1(fumonisin B1,FB1)与载体蛋白进行偶联制备免疫抗原FB1-BSA及包被抗原FB1-OVA,比较了不同偶联条件对抗原合成的影响。紫外扫描初步显示载体蛋白与伏马菌素偶联成功。皮下注射免疫BALB/c小鼠,获抗FB1多克隆抗体,间接非竞争ELISA分析所得抗血清效价,最高可达1∶23000,间接竞争ELISA显示所制备的抗血清能有效识别伏马菌素B1,与脱氧雪腐镰刀菌烯醇(DON)、玉米赤霉烯酮(ZEN)、T-2毒素无交叉反应。     

Prostacyclin synthesis induced in vascular cells by interleukin-1

Supernatants from cultures of human monocytes that had been stimulated with endotoxin or silica induced the synthesis of prostacyclin in endothelial and smooth muscle cells. The lymphokine mediating these effects on the cells of the blood vessel wall was identified as interleukin-1; interferons and interleukin-2 were inactive. Interleukin-1-induced prostacyclin synthesis represents a new aspect of the interaction between the immune system (as well as other tissues) and the vessel wall and may serve as a basis for the development of new strategies in antithrombotic therapy.     

Infection of normal human epithelial cells by Epstein-Barr virus

Primary cultures of epithelial cells were grown from the tonsils and adenoids of patients with diseases not related to Epstein-Barr virus. The cells could not be infected by Epstein-Barr virus. Fluorescein-labeled Epstein-Barr virus and a cytofluorograph were then used to show that the epithelial cells do not have detectable receptors for the virus. However, implantation with Epstein-Barr virus receptors gave the cells the ability to bind the labeled virus. One to 5 percent of receptor-implanted cells exposed to the transforming B95-8 substrain of the virus expressed Epstein-Barr nuclear antigen. The early and viral capsid Epstein-Barr virus-determined antigens were not detected in the virus-infected cultures. The results show that normal human epithelial cells from the nasopharynx become susceptible to infection by Epstein-Barr virus when the membrane barrier resulting from the lack of viral receptors is overcome by receptor implantation.     

Homology of cytokine synthesis inhibitory factor (IL-10) to the Epstein-Barr virus gene BCRFI

Complementary DNA clones encoding mouse cytokine synthesis inhibitory factor (CSIF; interleukin-10), which inhibits cytokine synthesis by TH1 helper T cells, were isolated and expressed. The predicted protein sequence shows extensive homology with an uncharacterized open reading frame, BCRFI, in the Epstein-Barr virus genome, suggesting the possibility that this herpes virus exploits the biological activity of a captured cytokine gene to enhance its survival in the host.     

Epstein-Barr virus: inhibition of replication by three new drugs

Epstein-Barr virus (EBV) is the cause of infectious mononucleosis and is associated with three human malignancies. Acyclovir [9-(2-hydroxyethoxymethyl)guanine], the first clinically useful drug effective against replication of EBV, is without effect against latent or persistent EBV infection. Three nucleoside analogs, E-5-(2-bromovinyl)-2'-deoxyuridine, 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodocytosine, and 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-methyluracil are potent inhibitors of EBV replication in vitro. Moreover, in contrast to the reversibility of viral inhibition by Acyclovir, these three drugs have prolonged effects in suppressing viral replication even after the drugs are removed from persistently infected cell cultures.     

Control of behavior by presentation of an imprinted stimulus

When presentation of an imprinted stimulus is contingent upon an arbitrarily chosen response, the rate of emission of this response increases. This control of responding requires a moving imprinted stimulus and does not require a following response by the duck.     

Blocking of HIV-1 infectivity by a soluble, secreted form of the CD4 antigen

The initial event in the infection of human T lymphocytes, macrophages, and other cells by human immunodeficiency virus (HIV-1) is the attachment of the HIV-1 envelope glycoprotein gp120 to its cellular receptor, CD4. As a step toward designing antagonists of this binding event, soluble, secreted forms of CD4 were produced by transfection of mammalian cells with vectors encoding versions of CD4 lacking its transmembrane and cytoplasmic domains. The soluble CD4 so produced binds gp120 with an affinity and specificity comparable to intact CD4 and is capable of neutralizing the infectivity of HIV-1. These studies reveal that the high-affinity CD4-gp120 interaction does not require other cell or viral components and may establish a novel basis for therapeutic intervention in the acquired immune deficiency syndrome (AIDS).     

伏马菌素B_1人工抗原的鉴定及抗体的制备

采用戊二醛(GA)一步法将半抗原伏马菌素B1(FB1)分别与鸡卵清蛋白(OVA)、牛血清白蛋白(BSA)偶联,制备2种具有免疫原性的FB1人工抗原FB1-OVA和FB1-BSA。分别采用凝胶电泳法、紫外光谱法(UV)、红外光谱法(IR)、基质辅助激光分析电离飞行时间质谱法(MALDI-TOF-MS)4种方法鉴定人工抗原偶联效果并测定偶联比。将FB1-BSA作为免疫抗原免疫BALB/c小鼠,FB1-OVA作为固相包被抗原,采用间接酶联免疫吸附法(i-ELISA)测定小鼠抗血清滴度。结果表明:4种方法均鉴定FB1人工抗原合成成功。凝胶电泳法测定FB1-OVA和FB1-BSA相对分子质量分别约为50 000和75 000。MALDI-TOF-MS测定FB1-OVA和FB1-BSA相对分子质量分别为48 009.212和74 355.301,并精确计算FB1-OVA和FB1-BSA偶联比分别为5∶1和10∶1。FB1-BSA免疫后小鼠的抗血清效价为1∶1.25×105,并具有较高灵敏度。     

豆状带绦虫抗原的SDS-PAGE及Western-blot分析

为筛选豆状囊尾蚴的特异性抗原,采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)和免疫印迹(Western-blot)技术对自然感染的豆状带绦虫成虫、幼虫的头节、囊壁可溶性抗原及囊液抗原进行了分析.结果表明:从豆状带绦虫不同发育阶段的虫体中分离出5~12条主要蛋白区带,分子质量为25~114ku.以第7周自然感染家兔血清对7种虫体抗原进行的Western-blot分析显示,7种虫体抗原在42、57、63ku处均能被兔抗豆状囊尾蚴血清识别.以家兔阳性血清中提取出来的IgG免疫球蛋白对7种虫体抗原进行的Western-blot分析显示,7种虫体抗原在63ku处均能被兔抗豆状囊尾蚴血清识别.说明63ku蛋白带可作为预防兔豆状囊尾蚴病的候选疫苗抗原.试验初步阐明了豆状带绦虫7种不同抗原的部分生化特性,为对该抗原的进一步深入研究奠定了基础.     

6 -hydroxy- 1 -tetrahydrocannabinol synthesis and biological activity

6beta-Hydroxy-delta(1)-tetrahydrocannabinol, a metabolite of delta(1)-tetrahydrocannabinol has been synthesized from delta(6)-tetrahydrocannabinol. It shows high tetrahydrocannabinol-type activity in rhesus monkeys. The implications of this funding are discussed.     

Differential reactivity of human serums with early antigens induced by Epstein-Barr virus

Inoculation of 64-10 or Raji cultures with Epstein-Barr virus derived from the HRI-K clone of the P3J Burkitt's lymphoma line caused abortive infections in most of the lymphoblastoid cells with synthesis of "early antigens" but few, if any, capsids. Antibodies to early antigens were detected by indirect immunofluorescence in serums of many patients with infectious mononucleosis, Burkitt's lymphoma, or nasopharyngeal carcinoma. These antibodies were rarely present in other serums even though some of them showed high titers of antibodies to Epstein-Barr virus when assayed on EB3 Burkitt tumor cells; they also prevented synthesis of early antigens, provided the serums were mixed with the virus prior to inoculation. Antibodies to early antigens possibly reflect current or recent disease processes that are associated with the virus.     

2-巯基吡啶-N-氧化物的合成方法及其用途

对 2 -巯基吡啶 - N-氧化物 (PTO)的 4类合成方法 (2 -卤吡啶氧化法、氢氧化钠催化吡啶氧化法、2 -羧酸吡啶 - 1-氧化物金属盐脱羧法、1-氧化吡啶同 Na H和 L i H等强碱作用的方法 )进行了综述 ;并总结了 PTO及其金属盐的广谱杀菌防霉活性及其在农业、医学、化学化工等领域的应用。