双特异性单链抗体介导的T细胞对前列腺癌细胞的杀伤作用

目的 研究并比较两种抗人γ-精浆蛋白/抗CD3双特异性单链抗体介导T细胞杀伤前列腺癌细胞的作用.方法 利用流式细胞仪分析双特异性单链抗体(BsAb)及多价双特异性单链抗体(mBsAb)与LNCaP细胞和Jurkat细胞的亲和力;将LNCaP细胞作为靶细胞,分为抗体浓度固定组和效应细胞/靶细胞比例固定组,利用51Cr释放试验评价两种双特异性单链抗体在体外介导T细胞杀伤靶细胞的能力;将Jurkat细胞种植裸鼠后,建立裸鼠前列腺癌模型,并分为非治疗组、对照组、BsAb组和mBsAb组,进一步评价两种双特异性单链抗体在体内介导T细胞杀伤靶细胞的能力.结果 流式细胞仪结果显示:BsAb和mBsAb均可特异性结合LNCaP细胞和Jurkat细胞,阳性结合率分别为56.3%、55.4%和74%、83%.51Cr释放试验结果显示:在体外,BsAb和mBsAb均可介导T细胞对前列腺癌细胞的杀伤,并且T细胞的杀伤效率与抗体浓度和效应细胞/靶细胞比例呈正相关.与非治疗组和对照组比较,接种前列腺癌细胞的裸鼠在体内注射激活的细胞毒T细胞的同时分别接受两种抗体的治疗后,肿瘤生长均明显受到抑制(P＜0.05).另外,体外介导杀伤作用和体内抑制肿瘤生长等方面,多价双特异性抗体的效果明显优于双特异性抗体.结论 同时识别人γ-精浆蛋白和CD3分子的双特异性单链抗体可有效地介导T细胞对前列腺癌细胞的杀伤作用,并且双特异性单链抗体四聚体的形成可明显改善抗体介导杀伤作用的效率.     

微型双功能抗体抗CD3／抗CD20的构建和表达

目的：构建和表达抗CD3／抗CD20微型双功能抗体,并测定微型双功能抗体的生物学活性。方法：采用PCR和overlap PCR方法构建抗CD3／抗CD20微型双功能抗体,并用双脱氧终止法测定DNA序列;采用亲和层析法纯化该产物,并用Western blot和分了排阻层析鉴定纯化产物;采用FACS法和玫瑰花环试验鉴定纯化产物与靶细胞的结合活性。结果：DNA序列测定结果表明：抗CD3／抗CD20微型双功能抗体已构建成功,表达可溶性产物的产量达1mg/ml以上,纯化产物中二聚体的比例达90％,具有与Jurkat(CD3^ 0和Daudi细胞（CD20^ ）结合的活性,且能同时与Jurkat和Daudi细胞结合形成玫瑰花环。结论：利用Diabody形式,首次成功地构建了抗CD3／抗CD20微型双功能抗体,并获得较高表达,表达产物具有与相应2个靶抗原结合的活性。     

抗人卵巢癌×抗人CD3双特异单链抗体介导的效应细胞在体外对卵巢癌细胞的杀伤作用

目的　研究双特异单链抗体 (scBsAb)介导的Jurkat细胞 (CD3+ )及人外周血单个核细胞(PBMC)在体外对人卵巢癌细胞株SKOV3细胞的杀伤活性 ,从而探讨其用于卵巢癌治疗的可能性。方法以抗人卵巢癌×抗人CD3scBsAb激活效应细胞 ,以SKOV3为靶细胞 ,用MTT法测定不同实验条件下的杀伤活性。结果　 (1)以重组白细胞介素 2 (rIL 2 )、抗CD3单克隆抗体、抗CD2 8重链单域抗体 (VH)预刺激Jurkat及PBMC细胞比单纯用scBsAb激活效应细胞杀伤活性高 ;(2 )以Jurkat细胞或PBMC细胞作为杀伤细胞可得到相似的杀伤活性 ,最高杀伤率均在 75 %左右 ;(3)杀伤活性与scBsAb的浓度、作用时间及效靶比有关。对于Jurkat细胞 ,在抗体终浓度为 2 1μg ml,反应时间为 4 8h ,效靶比为 10∶1时达到最大杀伤率 74 .8% ;对于PBMC细胞 ,在抗体浓度为 2 0 μg ml,反应时间为 72h ,效靶比为 1∶1时达到最大杀伤率73.1%。 (4 )多因子联合应用能有效提高杀伤活性。结论　scBsAb在体外能够有效介导效应细胞杀伤肿瘤细胞 ,有明显的抗癌作用 ,具有潜在的应用前景。     

抗人喉癌/抗CD3双功能抗体的制备及对Hep-2细胞株的杀伤作用

目的：研究制备抗人喉癌／抗CD3双功能抗体，探讨喉癌主动免疫治疗。方法：以化学方法将人喉癌及抗CD3单克隆抗体交联为双功能抗体，进行介导对肿瘤细胞的杀伤作用。结果：该双功能抗体介导效应细胞对靶细胞的杀伤率高于抗CD3的介导作用，并随着效靶比的提高而升高。结论：采用化学交联法制备的抗人喉癌／CD3双功能抗体具有潜在的临床应用价值。     

免疫亲和层析法纯化抗Pgp/抗CD3双功能抗体

目的：制备可以纯化抗Pgp/抗CD3双功能抗体的免疫亲和层析柱。方法：纯化的抗抗CD3ScFv单克隆抗体与预活化的Sepharose4B偶联制成免疫亲和层析柱,采用自制的免疫亲和层析柱纯化由摇瓶发酵获得的抗Pgp/抗CD3双功能抗体,采用间接免疫荧光法测定抗CD3/抗Pgp微型双功能抗体能与Jurkat细胞及K562/A02细胞特异性结合活性。结果：成功地制备了可以纯化抗Pgp/抗CD3双功能抗体的免疫亲和层析柱,采用此柱纯化的抗体与Jurkat细胞及K562/A02细胞特异性结合的活性与带有E-tag纯化标志的抗体基本一致。结论：此介质可以替代价格高昂的E-tag亲和层析介质在纯化Pgp/抗CD3双特异双功能抗体中的应用,同时还可以避免由于E-tag纯化标志而带来的免疫原性问题,此项研究工作为抗Pgp/抗CD3双功能抗体将来在临床应用奠定了基础。     

双功能单抗介导CD3AK细胞对人原发性肝癌的杀伤作用

目的了解CD3AK细胞在双功能单抗介导下对人原发性肝癌(PLC)的杀伤作用.方法用二次杂交瘤方法制备得双功能单抗(GP95×CD3),将该单抗激活人淋巴细胞,分别测定后者对PLC细胞的体内外杀伤效应.结果GP95×CD3能显著提高T细胞与癌细胞的结合率,对靶细胞的杀伤具有较强的特异性.体外试验明显增加细胞毒效应,裸鼠体内试验具有显著抑制肝癌生长的作用.结论GP95×CD3在体内外均可介导CD3AK细胞对PLC的杀伤作用.     

抗CD3—抗胶质瘤双特异性抗体的制备及其细胞毒活性作…

采用化学联法制备抗ＣＤ３－抗胶质瘤双特异性的抗体，其分子结构为杂合的Ｆ（ａｂ‘）２片段、结合率试验证明，此双抗能同时识别并结合ＬＡＫ细胞和胶质瘤细胞，在细胞毒性试验中，虽然双抗，ＣＤ３单抗和ＳＺ－３９单抗混和物均能提高ＬＡＫ细胞对胶质瘤细胞的杀伤作用，但双抗的作用特别显著，增强效应为１４８％，而在以非胶质瘤细胞为靶细胞时，双抗虽有增强作用，但低于ＣＤ３单抗的作用。     

人胃癌双功能抗体制备的研究

以不同技术路线制备Ｐ２１０／ＭＭＣ，Ｐ２１０／ＴＮＰ及Ｐ４０／ＣＤ３三种双功能抗体（ＢｓＡｂ）。在１１次细胞融合中，接种７４８４孔，获１５株二次杂交瘤，其中５株分泌ＢｓＡｂ。将亲本杂交瘤分别诱变为ＨＧＰＲＴ＾－及ＴＫ＾－，融合后以ＨＡＴ选择培养并辅以饲养细胞较易获得二次杂交瘤。证明两种抗原交互反应的桥联试验，特别是当二次杂交瘤分泌不同类别的Ｉｇ时，对于确证ＢｓＡｂ的存在有着重要意义。本文首次报告，     

抗Pgp/抗CD3双特异双链抗体的生物学活性研究

目的　研究抗Pgp 抗CD3双特异双链抗体介导的特异性靶向杀伤活性。方法　采用亲和层析法分离纯化本室构建的抗Pgp 抗CD3双特异双链抗体可溶性表达产物 ,并用SDS PAGE、Westernblot及抗活细胞间接免疫荧光法鉴定纯化产物 ;采用51 Cr释放试验测定其介导的体外靶向杀伤活性。结果　纯化的抗Pgp 抗CD3双特异双链抗体具有与Jurkat细胞 (CD3 )和K5 6 2 A0 2 (Pgp )细胞结合的活性 ;抗Pgp 抗CD3双特异双链抗体具有介导激活的T淋巴细胞杀伤Pgp表达阳性的耐药肿瘤细胞的作用 ,杀伤作用的强弱显示出效靶比和剂量依赖关系 ,且可被CD3ScFv或PgpScFv特异性的阻断。结论　抗Pgp 抗CD3微型双功能抗体有望成为治疗耐药肿瘤 ,特别是肿瘤残留灶和微小转移灶的治疗的一种新策略。     

抗CD3/抗CD20双特异双链抗体的生物学活性研究

目的研究抗CD3/抗CD20双特异双链抗体的生物学活性.方法采用亲和层析法纯化本室构建的抗CD3/抗CD20双特异双链抗体可溶性表达产物,并用SDS-PAGE,Westernblot和分子排阻层析鉴定纯化产物;采用FACS法和玫瑰花环试验测定纯化产物与靶细胞的结合活性;采用3H-TdR掺入实验和51Cr释放试验测定该双特异双链抗体的生物学性质.结果纯化的抗CD3/抗CD20双特异双链抗体具有与Jurkat(CD3+)和Daudi细胞(CD20+)的结合活性,且能同时与Jurkat和Daudi细胞结合形成玫瑰花环,并能竞争性封闭亲代鼠源性抗体HIT3a和HI47与Jurkat和Daudi细胞的结合位点;该双特异双链抗体具有促有丝分裂原作用和介导激活的T细胞杀伤Daudi细胞的活性.结论抗CD3/抗CD20双特异双链抗体具有与亲代鼠源性抗体HIT3a和HI47相同的性质,且能介导激活的T细胞杀伤表达CD20抗原的肿瘤细胞,是一个有望用于B细胞恶性肿瘤临床治疗的双特异性抗体.     

Immunosuppressive properties of anti-CD3 single-chain Fv and diabody

The mouse anti-human CD3 monoclonal antibody OKT3 is a potent immunosuppressive agent used in clinical transplantation. However, OKT3 therapy is associated with unpleasant and often serious side effects which appear to result from cytokine release, complement activation and a human anti-mouse antibody (HAMA) response. To decrease these adverse side effects, we constructed antibody fragments comprising OKT3 variable domains without any constant domains. Single-chain Fv (scFv) monomers, dimers and trimers were generated by changing the linker length between the V(H) and V(L) domains. The linkers used were the natural extensions of the V(H) into the C(H)1 domain. The dimeric molecules (diabodies) demonstrated the best CD3-binding activity. The diabody with the six amino acid linker was produced in bacteria with a tenfold higher yield than other scFvs and possessed CD3-binding affinity approaching that of the parental mAb. In contrast to OKT3 mAb, the anti-CD3 diabody and scFv monomer did not cause any T-cell activation and cytokine release in vitro, while demonstrating CD3 modulation. In mixed lymphocyte cultures, both diabody and scFv, but not the monoclonal antibody OKT3, were able to suppress T-cell activation and secretion of IL-2 and IFN-gamma in a dose-dependent manner. The anti-CD3 diabody may provide a potent immunosuppressive drug with low toxicity and immunogenicity.     

Specific binding of Fyn and phosphatidylinositol 3-kinase to the B cell surface glycoprotein CD19 through their src homology 2 domains

CD 19 is a B cell surface protein capable of forming non-covalent molecular complexes with a number of other B cell surface proteins including the CD21/CD81/Leu-13 complex as well as with surface immunoglobulin. CD19 tyrosine phosphorylation increases after B cell activation, and is proposed to play a role in signal transduction through its cytoplasmic domain, which contains nine tyrosine residues. Several second messenger proteins have been shown to immunoprecipitate with CD 19, including p59 Fyn (Fyn), p59 Lyn (Lyn) and phosphatidylinositol-3 kinase (PI-3 kinase). These associations are predicted to occur via the src-homology 2 (SH2) domains of the second messenger proteins. Two of the cytoplasmic tyrosines in the CD 19 cytoplasmic region contain the consensus binding sequence for the PI-3 kinase SH2 domain (Y^PO4-X-X-M). However, the reported consensus binding sequence for the Fyn and Lyn SH2 domains (Y^PO4-X-X-I/L) is not found in CD 19. We investigated the capacity of CD 19 cytoplasmic tyrosines to bind both Fyn and PI-3 kinase SH2-domain fusion proteins. In activated B cells, both Fyn and PI-3 kinase SH2-domain fusion proteins precipitate CD 19. Using synthetic tyrosine-phosphorylated peptides comprising each of the CD 19 cytoplasmic tyrosines and surrounding amino acids, we investigated the ability of the Fyn SH2 and PI-3 kinase SH2 fusion proteins to bind to the different CD 19 cytoplasmic phosphotyrosine peptides. ELISA revealed that the two CD 19 cytoplasmic tyrosine residues contained within the Y-X-X-M sequences (Y⁴⁸⁴ and Y⁵¹⁵) bound preferentially to the PI-3 kinase SH2-domain fusion proteins. Two different tyrosines (Y⁴⁰⁵ and Y⁴⁴⁵) bound preferentially to the Fyn SH2-domain fusion protein via a novel sequence, Y-E-N-D/E, different from that previously reported for the Fyn SH2 domain. In precipitation studies, peptide Y⁴⁸⁴ was able to compete with tyrosine phosphorylated CD 19 specifically for binding to the PI-3 kinase SH2 domain fusion proteins, while peptides Y⁴⁰⁵ and Y⁴⁴⁵ were able to compete specifically for binding to the Fyn SH2 domain fusion proteins. These results indicate that CD19 may be capable of binding both Fyn and PI-3 kinase concurrently, suggesting a mechanism for CD 19 signal transduction, in which binding of PI-3 kinase to the Fyn SH3 domain results in activation of PI-3 kinase.     

BsAb HER-2×CD3对过度表达HER-2乳腺癌细胞的细胞毒作用

目的 :研究应用抗HER 2抗原和CD3抗原的双向基因工程抗体BsAbHER 2×CD3介导T淋巴细胞对过度表达HER 2乳腺癌细胞的细胞毒作用。方法 :以过度表达HER 2的乳腺癌细胞株SK BR 3为靶细胞 ,T淋巴细胞为效应细胞 ,采用MTT法、3 H TdR掺入法测定BsAbHER 2×CD3对靶细胞、效应细胞的抑制作用及其介导的效应细胞对靶细胞的杀伤作用。结果 :BsAbHER 2×CD3具有MAbHER 2和MAbCD3的双重特性 ,既能抑制SK BR 3细胞生长 ,又可促进正常人外周血T淋巴细胞增殖。BsAbHER 2×CD3介导T淋巴细胞对靶细胞产生显著的细胞毒作用 ,明显强于MAbHER 2对靶细胞的作用 ,E∶T =2 0∶1为最佳效靶比。结论 :BsAbHER 2×CD3 ,既可以与HER 2过度表达的肿瘤细胞特异性结合 ,又可以介导T淋巴细胞对肿瘤细胞产生特异性杀伤作用 ,具有明显的抗肿瘤作用     

抗CD4单抗增强抗CD3单抗／IL—2活化的肿瘤特异性T细胞的抗瘤活性

目的探讨抗CD4mAb增强抗CD3mAb刺激的肿瘤特异性T细胞增殖和杀瘤活性的作用。方法将肿瘤细胞免疫的小鼠脾细胞,采用4种不同的方案培养1单独加2×104U/LrIL2IL2组2单独加抗CD3mAb抗CD3组3加抗CD3mAb48h后,再加入抗CD3mAb和2×104U/LrIL2抗CD3 IL2组4同时加抗CD3mAb和抗CD4mAb48h后,再加入抗CD3mAb、抗CD4mAb和2×104U/LrIL2抗CD3 IL2 抗CD4组。然后分别检测4组效应细胞的增殖水平、杀瘤活性及表型。结果抗CD3 IL2组细胞的3HTdR掺入量在第6,12和20d分别为:22045、13986和1931;抗CD3 IL2 抗CD4组细胞的3HTdR掺入量在第6、12和20d,分别为46193、31047和7443,后者明显高于前者P0.05。在培养12d时,抗CD3 IL2组的细胞对FBL3细胞株的最大杀伤率为83.6%;抗CD3 IL2 抗CD4组细胞的最大杀伤率为91.7%。细胞表型:FACS分析表明,抗CD3 IL2 抗CD4组培养12d的细胞,99%以上为Thy1.2 细胞,且CD4 、CD25 细胞的百分率均高于抗CD3 IL2组。结论抗CD4mAb对抗CD3mAb刺激、IL2诱导的肿瘤特异性T细胞的增殖和杀瘤活性具有增强作用。     

Acquisition of regulatory function by human CD8(+) T cells treated with anti-CD3 antibody requires TNF

Anti-CD3 mAb can modulate graft rejection and attenuate autoimmune diseases but their mechanism(s) of action remain unclear. CD8(+) T cells with regulatory function are induced in vitro by Teplizumab, a humanized anti-CD3 antibody and inhibit responses of autologous and allogeneic T cells. They inhibit CD4(+) T-cell proliferation by mechanisms involving TNF and CCL4, and by blocking target cell entry into G2/M phase of cell cycle but neither kill them, nor compete for IL-2. CD8(+) Treg can be isolated from peripheral blood following treatment of patients with Type 1 diabetes with Teplizumab, but not from untreated patients. The induction of CD8(+) Treg by anti-CD3 mAb requires TNF and signaling through the NF-κB cascade. The CD8(+) Treg express CD25, glucocorticoid-induced TNF receptor family, CTLA-4, Foxp3, and TNFR2, and the combined expression of TNFR2 and CD25 identifies a potent subpopulation of CD8(+) Treg. These studies have identified a novel mechanism of immune regulation by anti-CD3 mAb and markers that may be used to track inducible CD8(+) Treg in settings such as chronic inflammation or immune therapy.     

去除Etag标记的抗CD3/抗Pgp微型双功能抗体原核表达载体的构建及表达

目的:构建和表达不带Etag标记的抗CD3/抗Pgp微型双功能抗体(Diabody[CD3×Pgp]),并测定其生物学活性。方法:利用PCR方法构建不带Etag的Diabody[CD3×Pgp]原核表达载体,进行原核表达,制备抗抗CD3scFv亲和层析柱进行纯化,SDS-PAGE鉴定。通过间接免疫荧光法和竞争性免疫荧光结合流式细胞术(FCM)检测生物学活性。结果:无Etag的Diabody[CD3×Pgp]表达载体经测序证实其序列正确。SDS-PAGE电泳显示2条带,相对分子质量(Mr)分别为25000和26000,与预期Mr相符。去除Etag的Dia-body[CD3×Pgp]与K562/A02和Jurkat细胞结合阳性率分别为89.87%和83.95%。竞争结合实验中,与K562/A02和Jurkat细胞竞争后结合率分别为50.25%和43.78%。结论:成功构建了不带Etag的Diabody[CD3×Pgp]表达载体、进行原核表达及纯化。不带Etag的Diabody[CD3×Pgp]能特异性结合CD3和Pgp靶抗原,Etag标记去除后其生物学活性没有降低。