噬菌体展示 protein A 及 protein L Ig 结合单结构域随机组合文库及 Ig 亲和筛选

Protein A 和 protein L 是细菌产生的两种结构和功能均不同的免疫球蛋白 (immunoglobulin , Ig) 结合分子,在细菌的致病中起重要作用 . 用含 SacⅠ位点的特定引物 PCR 分别扩增制备 protein A 的 A 、 B 、 C 、 D 抗体结合结构域和 protein L 的 B3 抗体结合结构域,各结构域 DNA 片段经 SacⅠ酶切后,再随机连接形成各种不同长度的分子组合文库,将该文库呈现在噬菌体表面构建了噬菌体展示 Ig 结合分子单结构域随机组合文库,所建组合文库容量为 2.3×10⁶个菌落形成单位,滴度为 4.1×10¹¹TU/ml , 包含各种单结构域片段,并以随机方式连接 . 用人 Ig 对该文库进行 4 轮亲和筛选,随机挑选 36 个代表性的阳性克隆进行序列测定分析表明,亲和筛选获得了多种非天然形式存在的新的 Ig 结合分子结构,其中 32 个克隆具有由 protein L 的单结构域和 protein A 的单结构域间隔重复排列而成的特征性 (MDPL-MDPA)n 结构 . 对噬菌体展示 Ig 结合分子单结构域随机组合文库的体外分子进化研究的尝试,为 Ig 结合分子的结构和功能研究提供了一新的途径,也为 Ig 结合分子的定向改造打下基础 .     

新型受体药物CTLA4－Ig的应用

新型受体药物ＣＴＬＡ４－Ｉｇ的应用方向东,刘宏,王小宁（第一军医大学分子免疫学研究所,广州５１０５１５）关键词受体药物,免疫抑制剂,基因重组利用生物体的一些天然或改造的受体作为治疗用药是目前国际上研究的热点之一,特别是在筛选有效的免疫抑制剂方面。细胞...     

CTLA4Ig融合蛋白在CHO细胞中的表达

CTLA4Ig是人CTLA4胞外区与人免疫球蛋白铰链区、CH2区、CH3区组成的融合蛋白,可以与B7结合,通过阻断B7与CD28的结合,从而阻断B7介导的T细胞活化必需的共刺激信号,可作为免疫抑制剂用于器官移植。将CTLA4Ig融合分子克隆到真核表达载体pCI-dhfr,并用脂质体方法转染到COS7和CHO-dhfr-细胞中,用氨甲喋呤筛选转染的CHO-dhfr-细胞。用RT-PCR、ELISA、细胞免疫荧光染色和Western-blot鉴定重组蛋白的表达。采用A蛋白纯化重组蛋白。     

应用亲和免疫印迹技术检测血清微量单克隆Ig

介绍了一种简便、快速、灵敏的检测血清微量 mIg 的新方法——亲和印迹法.首先将特异性 Ab 结合到 NC 膜上,以薄层琼脂糖凝胶区带电泳把蛋白分离,蛋白经毛细印迹到 NC-Ab 膜上与其抗体亲和,再用酶标抗体探测被印迹之蛋白.2h 内可显示出 mIg 的特征.不需任何昂贵特殊设备.其敏感度大约是自然印迹法的10倍,是 IF银染色法的100倍.     

两种测定血清“Ig”方法的比较

两种测定血清“Ｉｇ”方法的比较大连市劳动卫生研究所大连１１６０１１曹桂荣,王月芬用高浓度抗体单扩敢法测定Ｉｇ．具有方法简便,稳定可靠等比点,但需要４８小时才能报告结果。我们的方法是将扩散温度４℃改为３７℃,扩散２０小时,再移放４℃４小时,整个过程只有...     

Polymeric Ig receptor: defender of the fort or Trojan horse?

The polymeric immunoglobulin receptor (pIgR) is important in host defense, transporting antibodies across mucosal epithelial cells. Recent work has shown that, using a protein that binds directly to the pIgR, Streptococcus pneumoniae can co-opt the transcytosis machinery and gain entry into airway epithelial cells.     

CTLA4Ig-IRES-OX40Ig重组腺病毒的构建及其生物学特性

利用基因重组技术,拼接目的基因CTLA4Ig-IRES-OX40Ig,并亚克隆入腺病毒载体pTrack-CMV中,构建pT/CTLA4Ig-IRES-OX40Ig载体,与pAdeasy-1共同转染BJ5183以进行同源重组,所获得的重组子用LipofectAMINE2000转染293A细胞包装病毒,获得了可同时分别表达CTLA4Ig和OX40Ig的重组腺病毒AdCTLA4Ig-IRES-OX40Ig,并进行扩增和滴度测定,用Western印迹鉴定293A细胞培养上清中目的基因的表达,用混合淋巴细胞反应研究其免疫抑制活性.利用上述方法成功构建了穿梭质粒pT/CTLA4Ig-IRES-OX40Ig;并且获得了重组腺病毒AdCTLA4Ig-IRES-OX40Ig,在感染的293A细胞的培养上清中可以同时检测到CTLA4Ig和OX40Ig分子;AdCTLA4Ig-IRES-OX40Ig、AdCTLA4Ig和AdOX40Ig感染的Lewis大鼠脾细胞(刺激细胞)对Balb/c小鼠的脾细胞(反应细胞)的增殖均具有抑制作用,但AdCTLA4Ig-IRES-OX40Ig感染组的抑制效率明显强于AdCTLA4Ig和AdOX40Ig感染组,体外实验证实该两种分子可协同作用,强烈抑制混合淋巴细胞反应.     

Ig heavy chain of the sturgeon Acipenser baeri : cDNA sequence and diversity

 To investigate the gene organization of the IGH locus, and the VH diversity of the Siberian sturgeon, a cDNA library was constructed and screened with VH-specific probes from two holostean fish. Isolated clones were analyzed and domain-specific probes used in rescreening of the library, Southern blot analysis, and northern blots. It was concluded that the Siberian sturgeon has one IGH locus with a translocon type of organization. Two allelic variants of the mu gene were found, with identities ranging from 80 to 100% for the different domains (highest for CH4 and lowest for CH2). Sturgeon CH sequences are most closely related to those of holostean fish. There are three distinct VH families, VHI grouping with mammalian clan III, VHII grouping with the teleost clan, and VHIII grouping with the archaic clan. The variability of the CDR 3 region is substantial, and we identified a number of conserved motifs in the D segment. Further, we deduced that there are at least nine different JH segments in the locus, contributing to the antibody repertoire of the sturgeon. The variable segments of the three families can be associated with any of the D or JH segments in the rearrangement. Sturgeon, in addition to the random rearrangement of VH, D, and JH segments, have exonuclease activity, and an introduction of N and probably P nucleotides at the site of rearrangement. Received: 2 March 1998 / Revised: 20 May 1998     

用Ig—SPA花环法检测人末稍血淋巴细胞的初步探讨

目前国内外多采用荧光抗体法检测 B淋巴细胞。即用 FITC 标记抗人免疫球蛋白(Ig),然后和人淋巴细胞作用,因 B细胞上有特异的膜表面免疫球蛋白(SmIg)可与抗人 Ig 结合,从而使 B 细胞显示荧光,借助荧光显微镜计算阳性细胞的百分率。此法由于标记荧光的抗人     

PD-L1 Ig在缓解肾移植急性排斥反应中的免疫调节作用

目的:探讨PD-L1 Ig(Programmed death ligand-1 immunoglobulin,程序性死亡配体-1免疫球蛋白)在缓解肾移植急性排斥反应中的免疫调节作用。方法:选择健康成年雄性Lewis大鼠24只作为供体,另取24只健康雄性Wistar大鼠作为受体。所选大鼠3个月龄,体重300 g±30 g,创建肾移植大鼠模型,并将其随机分为三组,空白对照组,对照组,和PD-L1 Ig组。空白对照组:灌注液,肾动脉灌注3分钟。PD-L1 Ig组:含1 m L的PD-L1 Ig的灌注液,肾动脉灌注3分钟。对照组不进行额外灌注操作。术后观察三组大鼠食欲、精神状态及生存情况。7天后取血标本观察肌酐、尿素氮、γ-干扰素(Interferon-γ, IFN-γ),白细胞介素-2(Interleukin-2, IL-2),白细胞介素-10 (Interleukin-10, IL-10)水平,同时三组各处死3只大鼠行肾脏病理学检查。结果:1.病理:对照组及空白对照组大鼠较模型大鼠有改善,仍有较多的炎细胞浸润,间质水肿,红细胞管型,肾小管上皮细胞脱落。而PD-L1 Ig组大鼠较模型大鼠、对照组及空白对照组有显著改善。2.生存状态和肾功能:PD-L1 Ig组大鼠生存时间最长50天,平均存活时间和体重均显著高于对照组和空白对照组,差异均有统计学意义(P0.05);血肌酐、尿素氮水平显著低于对照组和空白对照组,差异均有统计学意义(P0.05)。3.细胞因子变化:PD-L1 Ig组IFN-γ、IL-2水平显著低于空白对照组、对照组,差异均有统计学意义(P0.05);PD-L1 Ig组IL-10水平显著高于空白对照组、对照组,差异均有统计学意义(P0.05)。结论:PD-L1 Ig可降低IL-2和IFN-γ,提升IL-10,调节移植肾急性排斥反应的细胞因子平衡,改善肾功能,延长移植肾存活时间。     

IgG1 cytoplasmic tail is essential for cell surface expression in Igβ down-regulated cells

It has been shown that cytoplasmic tail of the IgG1 B cell receptors (BCRs) are essential for the induction of T-dependent immune responses. Also it has been revealed that unique tyrosine residue in the cytoplasmic tail of IgG2a has the potential of being phosphorylated at tyrosine and that this phosphorylation modulates BCR signaling. However, it still remains unclear whether such phosphorylation of IgG cytoplasmic tail is involved in the regulation of BCR surface expression. In order to approach the issue, we established and analyzed the cell lines which express wild-type or mutated forms of IgG1 BCR. As the result, we found that IgG1 BCR expressed normally on the surface of A20 B cell line independent of the cytoplasmic tail. In contrast, IgG1 BCR whose cytoplasmic tyrosine was replaced with glutamic acid which mimics phosphorylated tyrosine, was expressed most efficiently on the surface of non-B lineage cells and Igβ-down-regulated B cell lines. These results suggest that tyrosine residue in IgG cytoplasmic tail is playing a essential role for the efficient expression of IgG BCR on the cell surface when BCR associated signaling molecules, including Igβ, are down-regulated.     

Altered Ig hypermutation pattern and frequency in complementary mouse models of DNA polymerase ζ activity

To test the hypothesis that DNA polymerase ζ participates in Ig hypermutation, we generated two mouse models of Pol ζ function: a B cell-specific conditional knockout and a knock-in strain with a Pol ζ mutagenesis-enhancing mutation. Pol ζ-deficient B cells had a reduction in mutation frequency at Ig loci in the spleen and in Peyer's patches, whereas knock-in mice with a mutagenic Pol ζ displayed a marked increase in mutation frequency in Peyer's patches, revealing a pattern that was similar to mutations in yeast strains with a homologous mutation in the gene encoding the catalytic subunit of Pol ζ. Combined, these data are best explained by a direct role for DNA polymerase ζ in Ig hypermutation.     

EB病毒LMP1在鼻咽癌细胞中通过NFκB促进Igκ表达

利用已建立的受四环素调控ＬＭＰ１表达的鼻咽癌细胞系,用受ＣＭＶ启动子调控的ＮＦκＢ报道基因质粒ｐＮＦκＢ－ｌｕｃ的荧光素酶表达分析ＮＦκＢ的活性,并以核蛋白的Ｗｅｓｔｅｒｎ印迹方法观察ＬＭＰ１表达前后核内ＮＦκＢ组分ｐ６５量的改变,用全蛋白Ｗｅｓｔｅｒｎ印迹分析Ｉｇκ蛋白质的表达等方法,探讨在鼻咽癌中,ＥＢ病毒ＬＭＰ１蛋白是否通过核转录因子ＮＦκＢ促进免疫球蛋白κ轻链（Ｉｇκ）基因的表达。结果显示     

醛化人血清火箭免疫电泳Ig定量技术 Ⅱ.微量全血IgG定量法

报告了一种快速、微量、可重复的全血IgG定量法。用血色素吸管采耳垂血20微升,用生理盐水适当稀释后,按前文所述方法进行醛化和火箭免疫电泳,结果每一样品形成单一的火箭蜂。测定了十八名健康青壮年耳垂血和十六例慢性气管炎病人静脉血,并将同一个体的2毫升全血和1毫升血清的IgG含量作了比较,结果差别无统计学意义。根据正常人全血中血浆约占55%的体积,提出公式D_s=2D_b(1—5%),借以将每2毫升全血的IgG含量换算成1毫升血清IgG含量的近似值。同一份血标本分别用不同稀释液稀释,保存于4℃,并在两周内反复作八次电泳,测它们的IgG含量。变异系数分别为7.11%和5.47%。应用此法,IgG的定量只需几滴血,且很适合于对婴儿、儿童血中Ig水平的测定,也适合于对同一个体血中Ig动态变化的研究。