Per—S（2）蛋白T细胞识别的精细特异性

本文采用合成交叠肽扫描的方法在６种不同Ｈ－２单位型小鼠确定了ｄ／ｙ二种亚型Ｐｒｅ－Ｓ（２）蛋白的Ｔ细胞识别部位。发现：（１）在所观察的６种同类系小鼠均存在对Ｐｒｅ－Ｓ（２）蛋白反应的亚型特异性，这可能与Ｐｒｅ－Ｓ（２）蛋白分子的末端的多态性有关；（２）Ｐｒｅ－Ｓ（２）蛋白的Ｔ细胞识别部位在５种同类系小鼠位于Ｃ末端３２个氨基酸残基顺序内，在另一种同类系小鼠则位于Ｎ末端顺序，这与我们先前的理论观测结果     

Pre－S_（2）蛋白B细胞表位的精细特异性

采用我室建立的短肽点免疫结合试验确定Ｐｒｅ－Ｓ＿（２）蛋白Ｂ细胞表位的精细特异性。结果发现Ｐｒｅ－Ｓ＿（２）蛋白的Ｂ细胞识别部位（１４～２４）可进一步区分为两个部分交叠的表位：１４～２１和１８～２４，从而绘出了Ｐｒｅ－Ｓ＿（２）蛋白Ｂ细胞表位图谱。这对设计新一代疫苗及诊断试剂有指导意义。     

Pre—S（2）蛋白B细胞表位的精细特异性

采用我室建立的短肽点免疫结合试验确定Ｐｒｅ－Ｓ（２）蛋白Ｂ细胞表位的精细特异性。结果发现Ｐｒｅ－Ｓ（２）蛋白的Ｂ细胞识别部位（１４－２４）可进一步区分为两个部分交叠的表位：１４－２１和１８－２４，从而绘出了Ｐｒｅ－Ｓ（２）蛋白Ｂ细胞表位图谱。这对设计新一代疫苗及诊断试剂有指导意义。     

北方汉族群HLA—A2亚型分布及p53的合成肽体外诱导C …

目的 研究北方汉族人群中ＨＬＡ－Ａ２亚型的分布及树突状细胞提呈基于ｐ５３基因合成肽体外诱导特异性Ｔ杀伤细胞（ＣＴＬ）反应的影响。方法 利用ＰＣＲ－ＳＳＰ技术分析北方汉族人群中ＨＬ－Ａ２基因型及其亚型的分布,并在适当Ａ２亚型背景下,选择与ＨＬＡ－Ａ２０１分子具有高亲和性的２个来自ｐ５３蛋白及１个来自ＨＢＶ核心抗原的蛋白合成多肽,将其分别负载到经体外ＧＭ－ＣＳＦ＋ＩＬ－４刺激增殖的人脐带血树突状细胞（     

从HCV蛋白一级结构预测其C,E,NS5区的CD_4~ T细胞抗原位点

我们根据ＣＤ４＋Ｔ细胞识别抗原位点的物理化学和生物学特征，设计了一个具有查找两亲性螺旋状结构（ａｍｐｈｉｐａｔｈｉｃｈｅｌｉｘｓｔｒｕｃｔｕｒｅ）肽段功能的计算机程序。用该程序对ＨＣＶ－１型病毒Ｃ、Ｅ（Ｅ１、Ｅ２／ＮＳ１）、ＮＳ５蛋白一级结构进行分析，发现这些蛋白区存在ＣＤ４＋Ｔ细胞识别位点。此结果支持了ＣＤ４＋Ｔ细胞对ＨＣＶＣ，Ｅ，ＮＳ５区可发生增殖反应的结论。提示该程序可作为一种预测ＣＤ４＋Ｔ细胞识别ＨＣＶ抗原位点的方法。     

逆转录病毒载体介导乙型肝炎病毒反义基因的转录表达

为了探索在真核细胞内转录表达乙型肝炎病毒（ＨＢＶ）反义核酸的方法，用基因重组技术将ＨＢＶ前Ｃ／Ｃ基因（ＰｒｅＣ／Ｃ）和前Ｓ／Ｓ基因（ＰｒｅＳ／Ｓ）片段反向插入逆转录病毒载体质粒，再将重组体分别转染ＰＡ３１７包装细胞，进而获得能够介导ＨＢＶ反义基因向小鼠ＮＩＨ３Ｔ３细胞转移表达的重组逆转录病毒。经分子杂交试验表明，含有ＨＢＶ反义基因的重组逆转录病毒序列已经整合到转染的ＰＡ３１７细胞染色体上；转导的ＮＩＨ３Ｔ３细胞内有ＨＢＶ反义ＲＮＡ转录表达。结论：逆转录病毒载体包装细胞系统能够介导ＨＢＶ反义基因在真核细胞中转录表达，因而有可能利用反义技术和基因转移方法进行抗－ＨＢＶ基因治疗     

抗天花粉蛋白单抗用于天花粉蛋白免疫毒素的亲和纯化

天花粉蛋白（ＴＣＳ）是一种单链致核糖体失活的蛋白，用细胞融合技术筛选到一株分泌抗该蛋白单抗的杂交瘤细胞株（Ｔ１Ａ９），并将单抗Ｔ１Ａ９制成免疫亲和凝胶，用此亲和凝胶纯化以ＴＣＳ和抗人黑色素瘤单抗Ｎｇ７６构建的免疫毒素，能有效地分离掉样品中的游离抗体，提高免疫毒素的毒效。体外细胞毒性实验表明，亲和纯化的免疫毒素对黑色素瘤细胞（Ｍ２１）的杀伤作用比分子筛（ＳｅｐｈａｃｒｙｌＳ－２００）层析后的样品提高了６．３倍。它对Ｍ２１细胞的半致死浓度（ＩＣ＿（５０））为１．０×１０￣（－１０）ｍｏｌ／Ｌ。比ＴＣＳ和Ｎｇ７６的混合物的毒性（ＩＣ＿（５０）＝２．５×１０￣（－７）ｍｏｌ／Ｌ）提高了２５００倍。ＴＣＳ是制备免疫毒素的一种有效和常用的“弹头”，用此法纯化这类免疫毒素将会有一定的普遍性。     

ANALYSIS OF MOTIF IN TCR Vβ HV4 SEQUENCES BINDING SUPERANTIGEN TSST-1

首先对４１种人和小鼠的Ｔ细胞受体β链可变基因编码肽段（Ｖβ）的氨基酸序列进行多序列对准，就Ｖβ之第四高变区（ＨＶ４）片段进行比较，分析与超抗原毒素休克综合征毒素－１（ＴＳＳＴ－１）结合的四种Ｖβ（小鼠Ｖβ３、Ｖβ１５、Ｖβ１７和人Ｖβ２）之ＨＶ４序列内是否存在特定的氨基酸残基排列模式。结果发现：小鼠Ｖβ３和Ｖβ１７的ＨＶ４具有特异的ＲＦＳＡＸＣＸＳＮＳ模式，而小鼠Ｖβ１５和人Ｖβ２的ＨＶ４则含独特的ＫＦＸＩＸＨ模式。提示：与ＴＳＳＴ－１结合的四种Ｖβ所对应的Ｔ细胞识别表位可能不止一个。     

从HCV蛋白一级结构预测其C,E,NS5区的CD4^＋T细胞抗…

我们根据ＣＤ４＾＋Ｔ细胞识别抗原位占的物理化学和生物学特征，设计了一个具有查找两亲性螺旋结构（ａｍｐｈｉｐａｔｈｉｃ ｈｅｌｉｘ ｓｔｒｕｃｔｕｒ）肽段功能的计算机程序。用该程序对ＨＣＶ－１型病毒Ｃ、Ｅ（Ｅ１、Ｅ２／ＮＳ１）、Ｎ５蛋白一级结构进行分析，发现这些蛋白区存在的ＣＤ４＾＋Ｔ细胞识别位点。此结果支持了ＣＤ４＾＋Ｔ细胞对ＨＣＶ Ｃ，Ｅ，ＮＳ５区可发生增殖反应的结论。提示该程度可作为一种预测Ｃ     

人细胞色素P4502B6的GST融合蛋白及其抗体的制备

目的：获得纯化抗原用于制备ＣＹＰ２Ｂ６多克隆抗体方法：ＰＣＲ扩增目的基因片段,亚克隆入融合蛋白表达载体ＰＧＥＸ－３ｂ,构建了重组质粒ＰＧＥＸ／２Ｂ６。然后将该重组质粒转化大肠杆菌ＤＨ５α,ＩＰＴＧ诱导表达,ＳＤＳ＿ＰＡＧＥ分离,获纯化融合蛋白ＧＳＴ－２Ｂ６。用ＧＳＴ－３Ｂ２免疫ＢＡＬＢ／Ｃ小鼠,自腹水中获取ＣＹＰ２Ｂ６多克隆抗体。结果：融合蛋白ＧＳＴ－２Ｂ６（ＣＹＰ２Ｂ６２０２￣３５２ａａ）,并获     

Binding of divalent H-2Kd/IgG2aFc fusion protein to murine macrophage via Fc-FcR interaction

Peptide-MHC class I complex （pMHC） is a specific ligand for TCR recognition, and important for CD8^＋T cell activation. Here we described a genetically engineered divalent class I major histocompatibility complex （MHC） molecule, H-2K^d/IgG2aFc, a fusion protein consisting of the extracellular domains of H-2K^d, a murine MHC class I molecule, and the Fc region of IgG2a. This fusion protein is expected to attach the H-2K^d molecule to the surface of murine macrophage （MФ） through its Fc portion binding to Fc receptor （FcR） of MФ. cDNAs coding for the extracellular domains of H-2K^d and the Fc region of IgG2a were cloned respectively, and then recombined into plasmid pcDNA3.1（＋）. The H-2K^d/IgG2aFc protein was expressed by the plasmid-transfected cell line J558L, and purified from its supernatant with a Staphylococcal Protein A （SPA） column. The fusion protein showed a 58.4 kDa band as revealed by SDS-PAGE and Western blotting with murine IgG-specific antibody, which consists with that expected for extracellular domains of H-2K^d heavy chain plus the Fc region of IgG2a. The sandwich ELISA assay with antibodies specific for Fc portion and for H-2K^d indicated the fusion protein consists of both Fc portion and H-2K^d. Peritoneal MФ of C57BL/6 （H-2K^b） can be stained with H-2K^d specific monoclonal antibody （mAb） after incubated with the H-2K^d/IgG2aFc fusion protein. These results demonstrate the fusion protein can be used to attach the H-2K^d molecule to the surface of murine MФ, and provides a novel means to manipulate the T cell recognized epitope on the surface of murine MФ, which can be applied to activate antigen-specific cytotoxic T lymphocyte （CTL）.     

CD8 expression alters the fine specificity of an alloreactive MHC class I-specific T hybridoma.

The influence of CD8 on the fine specificity of MHC class I-restricted T cell allorecognition was evaluated by comparing the reactivity of CD8- and CD8-transfected forms of an allospecific, H-2Kb-restricted T hybridoma. The CD8- T hybridoma responded to cells expressing H-2Kb, H-2Kbm6, and the individual H-2Kb----bm10 back mutations 165V----M, 173K----E, and 174N----L. Under the same conditions the CD8- T hybridoma responded poorly or not at all to cells expressing H-2Kbm10, H-2Kbm8, the individual H-2Kb----bm10 back mutants 163T----A and 167W----S, and the individual H-2Kb----bm8 back mutations 22Y----F and 24E----S. In contrast, T hybridoma cells expressing high levels of CD8 reacted strongly with antigen presenting cells (APC) expressing H-2Kb and H-2Kbm6 molecules, as well as APC expressing H-2Kbm10 (weakly), H-2Kbm8, and all five individual H-2Kb----bm10 and the two H-2Kb----bm8 back mutants 22Y----F and 24E----S. The mutations which distinguish the T cell recognition of both H-2Kbm10 and H-2Kbm8 from H-2Kb are predicted to control the interaction of these class I molecules with antigenic peptides in the binding site, implying an important role for peptide antigen in T cell allorecognition. Nonetheless, CD8 expression by the H-2Kb-restricted T cells conferred novel or enhanced alloreactivity with cells expressing H-2Kbm10, H-2Kbm8, and each of the individual H-2Kb----bm10 and H-2Kb----bm8 back mutants. These findings reflect an important role for CD8 in influencing the fine specificity of MHC class I recognition by T cells and may indicate a limited structural role for peptide antigen in defining the ligand recognized by these alloreactive T cells.     

Fine antigenic specificity and genetic restriction of lysozyme-specific suppressor T cell factor produced by radiation leukemia virus-transformed suppressor T cells

Culture supernatants obtained from a radiation leukemia virus-transformed, hen egg-white lysozyme (HEL)-specific, suppressor T cell line are able, when injected into mice, to specifically suppress the anti-HEL antibody response. Suppression is observed on both primary and secondary anti-HEL antibody responses evaluated by direct and developed hemolytic plaque assays. Culture supernatants from this HEL-specific suppressor T cell line do not suppress the antibody response induced by a structurally related lysozyme, demonstrating the presence in the culture supernatant of a suppressor factor endowed with fine antigenic specificity. The suppressor factor is able to selectively suppress the anti-HEL antibody response induced by the N-terminal C-terminal peptide of the HEL molecule indicating that the fine specificity of this factor is restricted to an antigenic epitope present in this region of the HEL molecule. The suppressive activity is restricted by genes located within the H-2 complex and analysis of the suppression induced in recombinant mice demonstrates that the interaction between HEL-specific suppressor T cell factor and its cellular target requires identity in the I-J region of the H-2 complex.     

Preferential positive selection of V alpha 2+ CD8+ T cells in mouse strains expressing both H-2k and T cell receptor V alpha a haplotypes: determination with a V alpha 2-specific monoclonal antibody.

A monoclonal antibody, B20.1, was generated by fusing spleen cells from a Lou rat immunized with a soluble alpha/beta T cell receptor (TcR; V alpha 2/V beta 2) to mouse myeloma cells. Analysis of a panel of V alpha 2 mRNA-expressing T cell lines, hybridomas and transfectants revealed that the B20.1 antibody was specific for murine TcR V alpha 2 chains. The V alpha 2+ T cell population was examined in various inbred strains by two-color immunofluorescence using B20.1 and CD4- and CD8-specific antibodies with the following results: (a) the B20.1 antibody detected most members of the TcR V alpha 2 subfamily in the four TcR V alpha haplotypes tested; (b) in most strains examined, TcR V alpha 2 expression was biased to the CD4 subset (7.4%-17.4% V alpha 2+ T cells) as compared to the CD8 compartment (3.8%-13.3%); (c) TcR V alpha 2 expression was not influenced by Mls gene products and (d) increased positive selection of V alpha 2+ CD8+ T cells by H-2k major histocompatibility complex molecules occurred in all murine strains tested of the TcR V alpha a, but not in those bearing the TcR V alpha b haplotype.     

Qa-1/Tla region alloantigen-specific CTL with alpha beta receptor

Recent studies involving T cells that express gamma delta T-cell receptor (gamma delta TcR) have raised the possibility that Qa-1/Tla region class I major histocompatibility complex (MHC)-like molecules are antigen-presenting molecules for gamma delta TcR. In this report, cytotoxic T lymphocyte (CTL) clones specific for a Qa-1/Tla region gene product were isolated from a bulk B10. QBR (Kb, Ib, Dq Qa-1/Tlab) anti-B10.MBR (Kb, Ik, Dq, Qa/Tlaa) CTL line. These CTL lysed blasts from all Qa-1a strains regardless of the H-2 haplotype, indicating that the recognition of the Qa-1 antigen by these CTL is not restricted by other class I molecules. In bulk populations, CTL activity of this specificity was found only in the CD8+CD4- subpopulation. Accordingly, all established CTL clones were phenotyped as Thy-1+, CD8+CD4-. Furthermore, these clones were shown to express alpha beta TcR rather than gamma delta TcR. Thus, the results indicate that Qa-1 antigen can be recognized by alpha beta TcR T cells in a manner similar to recognition of classical class I molecules.     

An adjunct trait of HEL/I-Ab-specific T helper cell is sensitivity to antigen-specific immunosuppression

The present study tests whether the specific inhibition of helper T (Th) cell (and T hybridomas) by suppressor T (Ts) cells is a phenotypic trait of Th cells correlating with their acquired specificity for antigen/major histocompatibility complex or a genotypic trait not related to selection of the T cell repertoire for antigen. To do this we took advantage of the fact that H-2d parental strains of mice commonly restrict recognition of chicken egg-white lysozyme to the L3 peptide (a.a. 105-129) and H-2b parental mice to the L2 peptide (a.a. 13-105). F1 hybrids of these strains display two subsets of lysozyme-reactive T cells, one for each parental phenotype. Using (B10 X B10.D2)F1 mice reconstituted with B10.D2 bone marrow, we were able to develop genetic H-2d T cell clones that could express an atypical specificity, that is L2/I-Ab. Clones of this type, like genetic H-2b, are also sensitive to the inhibiting effects of HEL-activated Ts cells. To overcome some of the drawbacks of using heterogeneous populations of T, B and accessory cells in our assays, we constructed T hybridomas from HEL-immune, chimeric lymph node T cell blasts which respond to a unique antigen/major histocompatibility complex with production of the lymphokine interleukin 2. Our results indicate that all HEL/I-Ab-specific T cells (helper and hybridomas) are inhibited by suppression regardless of the T cell's haplotype at the H-2 locus: H-2b (B10), H-2d (D2) or H-2b,d (BDF1). Furthermore, there is a strict correlation between the antigen and I-A specificity: I-Ab-restricted T cells recognize non-L3 determinants even though some are derived from H-2d mice.     

Characterization of virus-specific cytotoxic T cell clones from allogeneic bone marrow chimeras

We established several H-2-restricted lymphocytic choriomeningitis virus (LCMV)-specific cytotoxic T cell clones from spleens of virus-primed C57BL/6 or C57BL/10 (H-2b) and B10.BR (H-2k) mice and from allogeneic C57BL/10----B10.BR and B10.BR----C57BL/10 bone marrow chimeras. Two T cell clones of H-2b origin and restricted to H-2b, 3 of H-2k origin and restricted to H-2k were compared with two clones each derived from the two types of chimeras. Their surface phenotype was found to be Lyt-2+, L3/T4- and KJ16-133+ (2 of 9). Clones from chimeras expressed bone marrow donor H-2 and are restricted to the recipient H-2. H-2k-restricted clones were all specific for Kk whereas all H-2b-restricted clones were specific for Db. These restriction specificities could be further defined by the blocking activity of various monoclonal anti-H-2 antibodies. Interestingly the anti-H-2Db antibodies blocked the restricted virus-specific killing activity of the clones derived B10.BR----C57BL/10 chimeras much more effectively than the activity of the clones derived from conventional H-2b mice. The various clones differed with respect to their fine specificity for LCMV strains. The 3 clones of conventional B10.BR origin only recognized LCMV-WE but not LCMV-Armstrong, Aggressive or Docile; H-2b-restricted conventional clones recognized target cells infected with all LCMV strains except LCMV-UBC-Docile; the T cell clones from the bone marrow chimeras recognized with one exception all LCMV strains tested.     

Identification of overlapping epitopes in mutant ras oncogene peptides that activate CD4+ and CD8+ T cell responses

Mutant ras p21 proteins contain sequences which distinguish them from normal endogenous ras and, thus, may represent unique epitopes for T cell recognition of antigen bearing tumor cells. Here, we examined the capacity of a mutant K-ras 9-mer peptide to induce in vivo CD8⁺ cytotoxic T lymphocytes (CTL). The peptide chosen reflected positions 4–12 of the point-mutated sequence of the K-ras oncogene encoding the Gly to Val substitution at codon 12. The overall rationale for selecting this particular 9-mer sequence was threefold: the mutant peptide contained a putative major histocompatibility complex (MHC) class I consensus anchor motif for murine H-2K^d; specific binding to MHC class I may then create an immunogenic complex for the induction of anti-ras CD8⁺ CTL; and finally, the mutant sequence overlapped with a newly characterized anti-ras CD4⁺ T helper type 1 epitope, which may have implications for the coordination and activation of both anti-ras immune mechanisms against the same target cell antigenic determinant. A functional interaction with H-2K^d was demonstrated with the mutant ras4–12(V12) peptide, but not the normal ras4–12(G12) peptide, which specifically inhibited an H-2K^d-restricted, anti-nucleoprotein NP147–155 CTL response in a dose-dependent fashion. An anti-ras CD8⁺ T cell line was then established from immune splenocytes of BALB/c (H-2^d) mice injected with ras4–12(V12) in adjuvant, which mediated peptide-specific lysis of syngeneic P815 tumor targets. Cytotoxicity was restricted by H-2K^d and strongly specific for the mutant ras peptide. Importantly, these anti-ras CTL specifically lysed a syngeneic tumor line (i.e. A20 lymphoma) transduced with the corresponding point-mutated ras oncogene, suggesting T cell receptor recognition of endogenously derived antigen. Overall, these data demonstrated that mutant ras p21 at codon 12 (Gly → Val) contained a peptide sequence which exhibited specific functional binding to a murine MHC class I molecule; the ability of the mutant, but not the normal sequence to bind selectively to murine MHC class I likely reflected the generation of a C-terminal anchor residue; and the ras 4–12(V12) peptide was immunogenic for the production of antigen-specific CD8⁺ CTL, which lysed in vitro a syngeneic tumor cell line harboring the mutant K-ras oncogene.     

Suicide selection of murine T helper clones specific for variable regions of the influenza hemagglutinin molecule

A negative selection procedure has been developed to obtain murine T helper clones specific for variable regions of the influenza A hemagglutinin. T cell lines, established from mice primed by intranasal infection with X31 (H3N2) virus, were cross-stimulated with natural variant viruses of known primary sequence (either A/TEXAS/1/77 or A/ENG878/69) and proliferating cells eliminated by treatment with the cell cycle-specific drug 5-bromodeoxyuridine. After two suicide cycles, T cell lines were subtype specific and failed to recognize the natural variants. Clones were established by limiting dilution and their specificity was determined against a panel of viruses. Extensive diversity was evident in the reactivity of clones from individual donors, and two major T cell recognition sites were defined in the globular head region of the hemagglutinin molecule.     

Fine specificity mapping of two allospecific T cell lines: recognition of private specificities in the H-2 IA subregion

Two allospecific T-cell lines, C.C3.11.75 (H-2d anti-H-2k) and B6.C.7.76 (H-2b anti-H-2d) established from mixed lymphocyte cultures, were selected by continuous antigenic stimulation over several years. Both cell lines proliferated to alloantigen, provided allohelp to B cells in the humoral antibody response, and one of them showed cytolytic activity. Using spleen cells from various congenic mouse strains, the specificity of antigen recognition was examined in order to examine whether there is a correlation between T cell function and antigen recognition. Results showed that in all functional assays. This shows that there is no obligatory correlation between T cell function and antigen recognition and may suggest that the T cell receptor repertoire is biased towards recognizing private specificities.