6C6鼠-人嵌合抗体的纯化及鉴定

采用基因工程技术 ,将小鼠 6C6单克隆抗体可变区基因与人抗体恒定区基因连接 ,构建了鼠 人 6C6嵌合抗体基因 ,并在CHO细胞中高效表达 .利用ProteinA亲和层析柱从细胞培养上清中分离纯化 6C6嵌合抗体 ,得到电泳纯度大于 98%的 6C6嵌合抗体 ,其重链 (5 5kD)和轻链 (2 4kD)符合IgG相对分子质量的理论值 .Western印迹、细胞免疫荧光和免疫组织化学实验结果均呈阳性 .表明6C6嵌合抗体可识别人乳腺癌细胞表面上的肿瘤相关抗原 ,保持了 6C6单克隆抗体的特性 。

^（99m）Tc直接法标记鼠／人嵌合抗体ccM_4及在动物体内分布研究和初步临床应用

ＳｎＣｌ２还原９９ｍＴｃＯ４后与２－巯基乙醇还原的ｃｃＭ４混合标记．薄层层析测定标记率为９８％．ｃｃＭ４嵌合抗体标记前后免疫活性没有明显变化（Ｐ＞０．０５）。动物体内分布实验结果显示：注射９９ｍＴｃ－ｃｃＭ４后１２ｈ．其放射性主要分布在肾（８．１７±１．０９ＩＤ％／ｇ）．肝（６．９４±１．７９ＩＤ％／ｇ）和血液（４．０３±１．０ＩＤ％／ｇ）；荷瘤裸鼠实验显示，１２５Ｉ－ｃｃＭ４瘤体内聚集量最多。９９ｍＴｃ－ｃｃＭ４初步应用于１０例胃癌患者．

抗人整合素ανβ_3 单抗E10鼠/人嵌合Fab噬菌体抗体的构建和表达

为构建抗人整合素ανβ3单抗E10鼠/人嵌合Fab噬菌体抗体表达载体,并在噬菌体表面表达,采用PCR方法从整合素ανβ3单抗E10ScFv载体中,扩增重链可变区VH和轻链可变区VL基因。将VH基因与人重链恒定区CH1基因连接,VL基因与人CK基因连接,分别构建了鼠/人嵌合重链FD基因和轻链基因,将其克隆入pComb3,构建了鼠/人嵌合Fab噬菌体抗体表达载体,用辅助噬菌体VCSM13超感染,间接ELISA及竞争抑制ELISA检测鼠/人嵌合Fab噬菌体抗体活性。结果成功构建了鼠/人嵌合Fab噬菌体抗体表达载体,并在噬菌体表面展示了可结合人整合素ανβ3抗原的鼠/人嵌合Fab抗体。

基因重组制备鼠/人嵌合McAb研究进展

利用淋巴细胞杂交瘤技术建立分泌特异性McAb杂交瘤细胞系,从中提取已重排的编码功能性Ig DNA 基因组(组建DNA文库)或成熟的IgH,L链mRNA片段(组建cDNA文库及制备探针),从而获得编码特异性McAb的V区基因。利用基因重组技术,将此来源于小鼠特异性IgH、L链的V区基因分别与编码人IgH、L链的C区基因相重组,构成鼠/人嵌合的Ig重组基因。然后将此重组嵌合Ig基因导入真核表达质粒(多为pSV2-ypt和pSV2-neo)_4经磷酸钙沉淀技术,原生质体融合技术或电穿孔导入技术(以后2种方法较为实用且转化频率较高),将此质粒转染哺乳动物非分泌型骨髓瘤细胞如Sp2/0等,经选择性培养基培养,从中筛选分必完整功能性的鼠/人嵌合McAb。将此cMcAb临床应用于人体内进行诊断和治疗时,具有原鼠亲本McAb特异性结合抗原的能力,同时还具备优于亲本鼠McAb的介导补体,细胞对靶抗原的杀伤和吞噬作用。而且不引起过敏反应或干扰治疗效果。从而给临床诊断,治疗恶性肿瘤。病毒,细菌等感染提供了一种新颖的免疫治疗试剂、本文对近年来鼠/人嵌合McAb的研究进展,基本技术及原理,优越性及不足之处作了简要阐述,并认为制备嵌合McAb是今后制备并取代人McAb研制及应用的一种发展趋向。

单克隆抗体药物研制的关键技术之一：抗体药物靶标筛选

单克隆抗体技术的研究经过了5个主要阶段：鼠源性抗体、鼠／人嵌合抗体、人源化抗体、人抗体及全人抗体。治疗性抗体的上述5个发展阶段使鼠源性蛋白成分分别从100％，下降至33％，乃至0，成为真正的全人抗体。随着单克隆抗体人源化程度的提高、

The Anti—tumor Effects of an Anti—CD71 Chimeric Antibody in Vitro and Its Distribution in a Tumor Xenograft Model

Objective To investigate the anti-tumor effects in vitro and in vivo distribution of the human/murine chimeric antibody (D2C). Methods The CD71 positive target cells (K562, GEM and SMMC7721) and the effector cells, freshly isolated human PBMC, with the ratio of target cells to effector cells 1:50, were incubated in various dilutions of D2C antibody ( Ab) . Antibody dependent cytotoxicity (AD-CC) was tested by using an LDH-release assay. Instead of effector cells, complement was added to the target cells (GEM, SMMC-7721) with various dilutions of D2C Ab. A method of counting death cells was used in complement dependent cytotoxicity (CDC) assay. Tumor localization and distribution of the chimeric antibody (D2C) were observed by labeling the chimeric Ab with radioiodine(131I) and injecting it into nude mice (Balb/c nu/nu) transplanted with human hepatocellular carcinoma cells (SMMC-7721).Results A significant ADCC was observed with the increased concentration of the D2C Ab. Cytolysis of CD71-positive target cells by the D2C Ab was found in the presence of fresh rabbit complement. Labeled D2C administered by intraperitoneal as well as tumor regional injection, was visualized by SPECT. The distribution of D2C Ab in murine organs and tissues showed that non-specific binding was lower following tumor regional administration than when the antibody was administered by an intraperitoneal injection. The human/murine chimeric antibody (D2C) has in vitro anti-tumor effects and can exert its effects in specific tumor localization. Its distribution and local effects in vivo can be detected by radioimmunoimaging.Conclusion CD71 human/murine chimeric antibody showed marked killing of tumor cells in vitro, and specific recognition and high affinity binding to tumor tissue in vivo

基于体细胞突变的单克隆抗体制备技术自主多样化库系统的原理与应用

自主多样化库（ADLib）是近年新建立的一种基于体细胞突变的生产抗体的系统，其原理为以鸡的传染性法式囊淋巴细胞瘤细胞（DT40，表达鸡IgM有膜结合与分泌两种形式）为靶细胞，利用-曲古酶抑菌素（TSA）抑制DT40的去乙酰活性酶，促进组蛋白乙酰化，从而造成免疫球蛋白基因高频转换，在细胞的表面展示膜结合IgM文库，最后通过抗原标记磁珠分选法从文库中选择有抗原特异性鸡源性抗体的细胞，培养细胞获得分泌性单克隆抗体IgM。进而，通过将人IgG的重链Fc段DNA序列插入DT40细胞IgM重链区相应位置，建立了合成人Fc段鸡Fab段的嵌合人IgG（重链Fc段决定免疫球蛋白类型）的ADLib系统。ADLib系统可应用于生产诊断与治疗性抗体药物的单克隆抗体（mAb）。