抗CD3/抗CD19微型双功能抗体的构建、表达及活性测定

背景与目的:微型双功能抗体是基因工程抗体的-种形式,它具有两个抗原结合位点,可选择性募集效应细胞到靶细胞周围,介导特异性杀伤作用.本实验构建抗CD3/抗CD19微型双功能抗体(diabody)载体,表达纯化后测定其生物学活性.方法:用重叠PCR(overlap PCR)和PCR方法,构建抗CD3/抗CD19 diabody 载体,转化感受态大肠埃希菌进行原核表达.表达产物经抗His-tag亲和层析柱分离纯化,12%SDS-PAGE电泳及Western blot鉴定.应用间接免疫荧光和竞争性免疫荧光结合流式细胞分析技术(PACS)检测生物学活性.结果:基因重组质粒经测序证实序列正确.抗CD3/抗CD19 diabody能够在原核表达系统中进行可溶性表达.12%SDS-PAGE显示28×103和26×103各有-条带,Western blot在28×103显示有条带,与预期相符.表达产物经纯化定量可达5 mg/L.FACS检测抗CD3/抗CD19 diabody可与CD19+ Raji细胞和CD3+ Jurkat细胞特异结合,并能竞争性抑制HIT3a和HIT19a与上述细胞的结合活性.结论:本实验成功构建了抗CD3/抗CD19 diabody,并且能够进行可溶性表达,可与CD19+ Raji细胞和CD3+ Jurkat细胞特异结合,为以后的抗体功能实验奠定了基础.     

肝癌细胞凋亡-抗HBx/抗CD3双功能抗体介导细胞毒性T细胞对靶细胞的杀伤

研究发现，针对效应细胞毒性T淋巴细胞[CTL]表面受体[TCB／CD3复合物]与肿瘤相关抗原的双功能抗体能有效地介导CTL对靶肿瘤细胞的杀伤。为此，我们通过细胞融合法经流式细胞仪[FACS]无菌分选建立了抗HBx／抗CD3二次杂交瘤，应用该二次杂交瘤所分泌的双特性单克隆抗体[BsAb]介导CTL在LTNM4裸鼠人肝癌模型进行了实验性治疗研究。     

抗CD3/抗TNP双功能抗体的制备及对胃癌细胞系的杀伤作用

:目的　以化学方法将抗CD3 及抗三硝基苯 (TNP)单克隆抗体交联为双功能抗体 ,研究此双功能抗体与任何TNP化的抗肿瘤单抗结合 ,介导对肿瘤细胞的杀伤作用。方法　分别纯化抗CD3 及抗TNP单克隆抗体 ,经二硫苏糖醇 (DTT)还原、偶联得到抗CD3 /抗TNP双抗。TNP化抗胃癌单抗PD4 、3H11与抗CD3 /抗TNP双抗介导人淋巴细胞对胃癌细胞系MGC80 3的细胞毒作用。结果　双抗与TNP化的单抗结合 ,介导效应细胞对靶细胞的杀伤率高于未TNP化单抗 ,并随着效靶比的提高而升高。结论　抗CD3 /抗TNP双抗能够与不同种类的TNP化单抗结合介导效应细胞杀伤靶细胞 ,有潜在的临床应用价值     

双功能抗体介导结肠癌细胞杀伤效应的研究

目的：研究抗CD3/抗TNP双功能抗体与TNP化抗癌胚抗原（CEA）McAb结合。在裸鼠体内对结肠癌细胞的杀伤作用。方法：将抗癌胚抗原单抗TNP化。TNP化后的抗CEA单抗（TNP-CEA），抗CD3/抗TNP双功能抗体，人淋巴细胞及结肠癌细胞CL187接种裸鼠体内。计算肿瘤生长体积，观察成瘤率。结果：双功能抗体能够介导PBLs对CL187细胞的杀伤作用。结肠癌细胞CL187的成瘤能力受到抑制，成瘤率为0/4。结论：此双功能抗体在免疫治疗中具有潜在的应用价值。     

抗CD3抗CEA抗体诱导杀伤细胞对胃癌体内杀伤的作用

目的探讨抗CD3抗CEA双特异性单链抗体诱导杀伤细胞(CIK细胞)在体内杀伤胃癌的作用。方法将BGC823细胞种植裸鼠后,建立裸鼠胃癌模型,分为3组,分别经尾静脉注入生理盐水、CIK细胞和CIK细胞+双特异性单抗,每3天治疗1次,共6次,取出肿瘤组织称重,并计算出各组的抑瘤率。结果在体内,CIK组和CIK+双特异性单抗组均可抑制肿瘤生长,抑瘤率分别为27.4%和41.7%,与对照组比较,差异均有统计学意义(均P<0.05)。CIK组与CIK+双特异性单抗组的瘤体积、瘤重、抑瘤率比较,差异均有统计学意义(均P<0.05)。结论 CIK细胞本身可以抑制肿瘤细胞的生长,在加入抗CD3抗CEA双特异性单链抗体后,抑瘤作用明显增强。     

抗EGFR／抗CD3双功能抗体对胃癌荷瘤小鼠的免疫治疗研究

目的 通过抗EGFR／抗CD3双功能抗体（EGFR/CD3 BsAb）治疗SGC7901胃癌细胞移植瘤小鼠模型,初步验证该抗体在体内对胃癌细胞的杀伤能力。方法 采取化学偶联法合成的EGFR/CD3 BsAb联合人外周血淋巴细胞（PBLS）经尾静脉给药注入荷SGC7901胃癌细胞移植瘤小鼠体内。实验裸鼠随机分为抗EGFR单抗联合PBLS组（抗EGFR组）、抗CD3单抗联合PBLS组（抗CD3组）、EGFR／CD3 BsAb联合PBLS组（EGFR/CD3 BsAb组）和空白对照组（生理盐水组）。治疗后检测并比较加药各组对胃癌细胞的杀伤能力。结果 EGFR／CD3 BsAb成功制备,分子量为43kD。EGFR／CD3 BsAb组裸鼠的肿瘤抑制率为(57.2±8.6）％,显著高于抗EGFR组的（38.5±6.1）％和抗CD3组的（6.9±7.6）％（P＜0.05）;治疗结束时EGFR／CD3 BsAb组的瘤重为（517.1±45.4）mg,显著低于抗EGFR组的（737.4±54.3）mg和抗CD3组的（1097.9±167.7）mg（P＜0.05）。各组移植瘤组织EGFR免疫组化染色均为强阳性。EGFR／CD3 BsAb组裸鼠肿瘤组织CD3免疫组化染色可见部分细胞呈阳性。透射电镜观察显示,EGFR／CD3 BsAb组和抗EGFR组可见肿瘤坏死。结论 EGFR／CD3 BsAb在体内条件下可能对胃癌有治疗作用。     

抗Pgp/抗CD3微型双功能抗体裸鼠体内分布研究

肿瘤部位的免疫效应细胞数量过少,难以达到杀伤肿瘤细胞的有效浓度是肿瘤逃避人体免疫系统监测的原因之一.     

微型双功能抗体介导人T细胞杀伤耐药实体瘤细胞

目的 探讨抗P-糖蛋白（P-gP）／抗CD3微型双功能抗体介导人T细胞杀伤耐药实体瘤细胞的作用。方法 采用抗E-tag亲和层析柱分离纯化抗P-gp／抗CD3微型双功能抗体,十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）进行鉴定;采用^51Cr释放实验,测定抗P-gP／抗CD3微型双功能抗体介导的人T细胞体外靶向杀伤活性;采用多药耐药（MDR）细胞系KB／MDR、敏感KB细胞裸鼠移植瘤模型,测定该微型双功能抗体介导的体内靶向杀伤活性。结果 纯化的抗P-gp／抗CD3微型双功能抗体,在相对分子质量28000和26000处各有1条蛋白带。在抗P-gp／抗CD3微型双功能抗体存在的情况下,激活的T淋巴细胞能够裂解KB／MDR细胞,且随着效靶比的增高而增高。抗P-gp／抗CD3微型双功能抗体联合人T淋巴细胞能有效抑制KB／MDR细胞裸鼠移植瘤的生长,而对敏感KB细胞移植瘤的生长无抑制作用。结论 抗P-gP／抗CD3微型双功能抗体在体内外均能介导人T淋巴细胞杀伤表达P-gP抗原的KB／MDR细胞,是有望用于耐药实体瘤临床治疗的双特异性抗体。     

抗B-CLL-IgM Id×抗CD3双功能抗体对LAK细胞杀伤活性的影响

抗肿瘤双特异性抗体(bispecific antibody,BsAb)由于具有同时与效应细胞及靶瘤细胞两种不同抗原特异性结合的双重特异性,从而提高了效应细胞对靶瘤细胞的特异性杀伤活性,因此,其在肿瘤靶向生物治疗中的应用日益受到重视.本研究通过体外实验,观察了抗人慢性B淋巴细胞白血病LgM独特型×抗CD3双特异性抗体(抗B-CLL-LgM Id×抗CD3 BsAb)对LAK细胞杀伤靶瘤细胞活性的影响,现报道如下.     

抗CD3／抗TNP双功能抗体的制备及对胃癌细胞系的杀伤作用

 目的　以化学方法将抗CD3及抗三硝基苯(TNP)单克隆抗体交联为双功能抗体,研究此双功能抗体与任何TNP化的抗肿瘤单抗结合,介导对肿瘤细胞的杀伤作用。方法　分别纯化抗CD3及抗TNP单克隆抗体,经二硫苏糖醇(DTT)还原、偶联得到抗CD3/抗TNP双抗。TNP化抗胃癌单抗PD4、3H11与抗CD3/抗TNP双抗介导人淋巴细胞对胃癌细胞系MGC803的细胞毒作用。结果　双抗与TNP化的单抗结合,介导效应细胞对靶细胞的杀伤率高于未TNP化单抗,并随着效靶比的提高而升高。结论　抗CD3/抗TNP双抗能够与不同种类的TNP化单抗结合介导效应细胞杀伤靶细胞,有潜在的临床应用价值。     

Serial killing of tumor cells by cytotoxic T cells redirected with a CD19-/CD3-bispecific single-chain antibody construct

Certain bispecific antibodies exhibit an extraordinary potency and efficacy for target cell lysis by eliciting a polyclonal T-cell response. One example is a CD19-/CD3-bispecific single-chain antibody construct (bscCD19xCD3), which at femtomolar concentrations can redirect cytotoxic T cells to eliminate human B lymphocytes, B lymphoma cell lines and patient-derived malignant B cells. Here we have further explored the basis for this high potency. Using video-assisted microscopy, bscCD19xCD3 was found to alter the motility and activity of T cells from a scanning to a killing mode. Individual T cells could eliminate multiple target cells within a 9 hr time period, resulting in nuclear fragmentation and membrane blebbing of target cells. Complete target cell elimination was observed within 24 hr at effector-to-target cell ratios as low as 1:5. Under optimal conditions, cell killing started within minutes after addition of bscCD19xCD3, suggesting that the rate of serial killing was mostly determined by T-cell movement and target cell scanning and lysis. At all times, T cells remained highly motile, and no clusters of T and target cells were induced by the bispecific antibody. Bystanding target-negative cells were not detectably affected. Repeated target cell lysis by bscCD19xCD3-activated T cells increased the proportion of CD19/CD3 double-positive T cells, which was most likely a consequence of transfer of CD19 from B to T cells during cytolytic synapse formation. To our knowledge, this is the first study showing that a bispecific antibody can sustain multiple rounds of target cell lysis by T cells.     

Disulfide-stabilized diabody antiCD19/antiCD3 exceeds its parental antibody in tumor-targeting activity

Background

A diabody is a bispecific antibody that is capable of recruiting a polyclonal T cell to antibody target-expressing tumor cells. However, the two chains of diabodies tend to dissociate because they are integrated non-covalently. Therefore, it is necessary to remodel the diabody to increase its stability in order to enhance the antitumor activity.

Methods

We constructed an antiCD3×antiCD19 diabody with one binding site for the T cell antigen receptor (TCRCD3) and the other for the B cell-specific antigen (CD19) by recombinant gene engineering technology. Cysteine residues were introduced into the V domains of the anti-CD3 segment. The stability and cytotoxicity of the two diabodies were compared in vitro and vivo.

Results

The disulfide-stabilized (ds) diabodies produced by Escherichia coli were secreted with high yields in a fully active form without a decrease in affinity. Compared with the parental diabody, the disulfide-stabilized (ds) diabody proved more stable in vitro and in vivo without reducing binding affinity. Both were able to effectively eliminate human lymphoma Raji cells by redirecting T lymphocytes in vitro and in vivo, but the ds diabody was more effective in inhibiting the growth of xenografts transplanted in BALB/C nude mice.

Conclusion

The antiCD3×antiCD19 ds diabody is more suitable for a controlled polyclonal T cell therapy of human CD19-positive B cell malignancies than its parental diabody.     

Effect of tetravalent bispecific CD19xCD3 recombinant antibody construct and CD28 costimulation on lysis of malignant B cells from patients with chronic lymphocytic leukemia by autologous T cells

To develop an effective antitumor immunotherapy for B-lineage non-Hodgkin's lymphoma, we constructed a tetravalent tandem diabody (tanDb) specific for both human CD19 (B-cell marker) and CD3 (T-cell antigen). Here, we report the effective killing of malignant primary B cells from patients with B-cell chronic lymphocytic leukemia (B-CLL) by autologous T cells induced by tanDb at very low E:T ratios. Mononuclear cells from patients with B-CLL were cultured with bispecific antibody fragments in either the presence or absence of monospecific anti-CD28 antibody. Use of tetravalent tanDbs caused almost quantitative elimination of malignant B cells from the blood samples of 19 patients and some cytotoxic activity in 3 of 23 analyzed cases. In contrast, the structurally similar but bivalent diabody and single-chain diabody demonstrated nearly no antitumor activity in an autologous system. tanDb-induced activation and proliferation of T cells occurred only in the presence of CD19+ target cells. Expression of the B7-1 (CD80) and B7-2 (CD86) molecules on the surface of leukemia cells made unnecessary the additional CD28-costimulation of T cells. When only a few tanDb molecules were present, the effect of CD28 costimulation on T-cell activation was more pronounced. Depending on the patient sample, we observed a 10- to 1,000-fold decrease of the half-maximal concentrations of tanDb for cell lysis. Upon CD28 crosslinking by agonistic MAb, specific tumor cell lysis was found at tanDb concentrations as low as 0.5 pM. These data demonstrate that the tetravalent CD19xCD3 tanDb might be a promising tool for the immunotherapy of human B-cell leukemias and lymphomas.     

Extremely potent,rapid and costimulation-independent cytotoxic T-cell response against lymphoma cells catalyzed by a single-chain bispecific antibody

A recent study reported on an anti-CD19/anti-CD3 single-chain bispecific antibody (bscCD19xCD3) exhibiting high activity against human B lymphoma cell lines (L?ffler et al., Blood 2000;95:2098-103). In the present study, we have explored in detail the in vitro efficacy, T-cell donor variability, binding characteristics, specificity, kinetics and interleukin-2 (IL-2) dependence of bscCD19xCD3. We found that a majority of human donor T cells tested (n = 86) gave half-maximal B-lymphoma cell lysis (ED(50)) within a range of 10-50 pg/ml bscCD19xCD3, corresponding to sub-picomolar concentrations of the bispecific antibody. Under identical experimental conditions, the anti-CD20 monoclonal antibody rituximab had an at least 100,000-fold lower in vitro efficacy. The extreme potency of bscCD19xCD3 was in sharp contrast to the relatively low affinity of the anti-CD3 and anti-CD19 single-chain Fv portions in K(D) ranges of 10(-7) and 10(-9) M, respectively. Cell lysis by bscCD19xCD3 was predominantly mediated by the population of CD8/CD45RO-positive T cells. Both immortalized CD4- and CD8-positive human T-cell clones were highly active effector cells as well. Cell lysis by bscCD19xCD3 was rapid and specific. The respective parental monoclonal antibodies inhibited cell lysis and CD19-negative cells were not harmed by T cells in the presence of high amounts of bscCD19xCD3. The potent T-cell stimulus IL-2 could not markedly augment the activity of bscCD19xCD3-stimulated T cells. In conclusion, bscCD19xCD3 could redirect unstimulated cytotoxic T cells against CD19-positive cells in an unexpectedly potent, rapid and specific fashion.     

靶向抗PD-1/CD19双特异性抗体的表达与活性鉴定

目的:重组表达和纯化靶向抗PD-1/CD19双特异性抗体(bispecific antibody, BsAb)并验证其活性.方法:以pCAR1为载体,利用分子克隆技术构建抗PD-1/CD19 BsAb真核表达载体,通过PEI试剂转染哺乳动物细胞株CHO-S瞬时表达抗体.利用亲和层析法对BsAb进行纯化,用SDS-PAG...     

The cytotoxic action of lymphokine activated killer cells upon the human glioma cell line U251 is stimulated by bispecific monoclonal antibody (MoAb) constructs

The ability of IL-2 stimulated mononuclear cells to kill the human glioblastoma cell line U251 has been investigated. Highest cytotoxic activity was generated in low cell density cultures incubated for 15 days with 250–1000 U/ml IL-2. Sub-optimal killing was noted, with cells only exposed to IL-2 for three days. Under the latter conditions, bispecific monoclonal antibodies (MoAbs) of either anti-CD3 or anti-CD16 and an anti-NCAM MoAb stimulated LAK cell activity markedly. Anti-CD16 conjugates were found more effective than anti-CD3 and (Fab)₂ constructs more efficacious than those made with whole Ig molecules. Maximal stimulation of LAK cell activity was noted with bispecific MoAbs. Little effect was observed with either single or mixtures of monomeric MoAbs. Furthermore, no effect of bispecific MoAbs was observed when target cells lacked expression of NCAM. These results could be of clinical importance as it is not always feasible to screen LAK cells for optimal activity before administration to patients. Whilst bispecific MoAbs have no effect on optimally stimulated LAK cells, they are not inhibitory and can stimulate killing under sub-optimal IL-2 stimulation.     

阿糖胞苷增强白血病细胞B7分子表达及促进双功能抗体对靶细胞的杀伤

目的：研究阿糖胞苷(cytarabine,AraC)对白血病细胞共刺激分子B7表达的影响,以及联合双功能抗体antiCD3/antiPgp介导T细胞对耐药白血病细胞的杀伤作用。方法：应用流式细胞术检测白血病细胞株K562和多药耐药白血病细胞株K562/A02细胞经AraC刺激不同时间后B71、B72分子的表达,RTPCR方法检测B71mRNA、B72 mRNA的表达,MTT法检测经AraC刺激的K562和K562/A02细胞对T淋巴细胞增殖的影响。CytoTox 96非放射性细胞毒性分析检测AraC联合antiCD3/antiPgp微型双功能抗体对人外周血淋巴细胞杀伤K562和K562/A02靶细胞的影响。结果：经AraC刺激的K562和K562/A02细胞B71、B72分子的表达较对照组明显升高;MTT结果显示,经AraC刺激的K562和K562/A02细胞能促进T淋巴细胞增殖;AraC联合antiCD3/antiPgp双功能抗体在0.39∶1~25∶1效靶比范围内,随着效靶比的升高,介导T淋巴细胞对K562和K562/A02细胞的杀伤率随之提高,对高表达Pgp的耐药K562/A02细胞尤为明显。结论：AraC可上调白血病细胞B7分子的表达,从而增强antiCD3/antiPgp双功能抗体介导的T细胞对靶细胞的体外杀伤作用。     

Heterodimeric bispecific antibody-derivatives against CD19 and CD16 induce effective antibody-dependent cellular cytotoxicity against B-lymphoid tumor cells

Bispecific scFv antibody-derivatives (bsscFvs) recruiting natural killer (NK) cells for the lysis of malignant cells have therapeutic potential. However, a bsscFv specific for the B-lymphoid tumor antigen CD19 and the trigger molecule CD16 on NK cells had similar affinities for both antigens (42 and 58nM, respectively) and was not optimal for cytotoxicity. Therefore, a bispecific tribody (bsTb) was constructed with two binding sites for CD19 and one for CD16. This bsTb contained a CD19-specific Fab fragment carrying a CD16-specific scFv fused to its light chain and a CD19-specific scFv fused to its heavy chain. The bsTb was compared with a bispecific bibody (bsBb) lacking the CD19-specific scFv. The bsTb had 3-fold greater avidity for CD19 than the bsBb (8 and 24nM, respectively), while both had equal affinity for CD16 (56nM). Both molecules mediated antibody-dependent cellular cytotoxicity (ADCC) of leukemia-derived SEM cells and primary cells from leukemia patients. The bsTb showed half-maximum effective concentrations (EC(50)) of 55pM and promoted equal lysis as the bsBb and the bsscFv at 6- and 12-fold lower concentrations, respectively. Among these three molecules the bsTb showed the most promising in vitro properties which are anticipated to be displayed also in vivo.