p53转染黑色素瘤细胞修饰的树突状细胞疫苗体外抗肿瘤作用的研究

利用野生型p53质粒转染黑色素瘤B16细胞,反复冻融法提取p53修饰的肿瘤抗原(p53-Ag),将抗原体外冲击同基因小鼠骨髓来源的树突状细胞(dendritic cells,DC)制备特异性DC肿瘤疫苗;观察DC诱导的淋巴细胞增殖反应和细胞毒性T淋巴细胞(cytotoxic T lymphocytes,CTL)对黑色素瘤细胞的细胞毒效应,分析其诱导肿瘤抗原特异性免疫应答的机制。结果显示,p53-肿瘤抗原冲击的DC可显著刺激淋巴细胞增殖,其诱导的CTL效应对肿瘤细胞也有很好的杀伤效果。     

Hs-exosomes致敏树突状细胞介导的抗卵巢癌免疫治疗的实验研究

目的检测卵巢癌细胞的外排小体Hs-exosomes致敏树突状细胞DC诱导T淋巴细胞CTL特异性杀伤卵巢癌细胞的能力。方法:分离卵巢癌细胞株2780释放的Hs-exosomes,将其致敏DC并与T淋巴细胞共培养,检测CTL体外细胞毒活性。结果:Hs-exosomes致敏DC激活CTL的抗肿瘤能力显著高于未致敏DC组。结论:2780细胞释放的Hs-exosomes致敏DC激活T淋巴细胞对肿瘤具有很强的杀伤作用。     

PEG10基因转染的树突状细胞疫苗对肝癌细胞的杀伤实验研究

目的:研究印记基因PEG10修饰的树突状细胞(DC)疫苗对肝癌细胞的杀伤效应,为肝癌的治疗提供新的策略。方法:将重组PEG10腺病毒rAd-PEG10感染HLA-A2阳性的人外周血来源的DC,制备PEG10基因修饰的DC疫苗,并在体外刺激HLA-A2阳性限制性的单个核细胞,酶联免疫斑点试验(Enzyme Linked Immunospot Assay, ELISPOT)和标准⁵¹Cr释放试验分别检测PEG10腺病毒感染的DC所诱导的特异性CTL活性,并检测对HLA-A2阳性的HepG2肝癌细胞的杀伤作用。结果:成功制备了PEG10基因修饰的树突状细胞(DC)疫苗,并在体外能有效诱导抗原特异性CTL效应,对HepG2肝癌细胞有明显的杀伤毒性。结论:PEG10基因修饰的树突状细胞能有效激发出特异性CTL应答,并对HepG2肝癌细胞有明显的杀伤毒性,为肝癌治疗提供了新思路。     

负载肿瘤细胞抗原的树突状细胞联合奥沙利铂抑制胰腺癌细胞BxPC-3增殖的实验研究

目的：化疗是晚期胰腺癌的主要治疗手段,但临床效果有限。为提高胰腺癌化疗效果,本研究将化疗药物奥沙利铂（OXA）联合肿瘤全细胞抗原负载的树突状细胞（DC）体外作用于胰腺癌BxPC-3细胞系,观察对其增殖的影响。方法：自健康人外周血中分离培养DC和T细胞。反复冻融BxPC．3细胞,使其裂解并提取全细胞抗原后致敏DC,再以DC激活T细胞。ELISA检测T细胞培养上清中IL-2、IL-4、IL-10和IFN-g的含量。将T细胞与不同浓度的OXA联合作用于BxPC-3细胞,MTT法检测杀伤率。结果：负载BxPC．3全细胞抗原的DC能显著激活T细胞使其成为效应性T细胞,并使其分泌IL-2和IFN—Y。不同浓度的OXA与效应性T细胞联合作用于BxPC．3细胞可明显抑制其增殖,且杀伤效果与OXA的浓度呈正相关。结论：负载BxPC-3全细胞抗原的DC可诱导出抗肿瘤的效应性T细胞,联合OXA能显著提高对BxPC-3细胞的杀伤作用。生物治疗联合化疗抑制胰腺癌细胞增殖的作用明显,具有较好的临床应用前景。     

树突状细胞对小剂量化疗疗效影响的基础研究

目的 研究树突状细胞对小剂量化疗疗效的影响,探讨小剂量化疗的可能机制.方法 以615小鼠的前胃癌细胞株(MFC)造模,在体外用rmGM-CSF和rmIL-4从荷瘤小鼠骨髓细胞分化、诱导未成熟树突状细胞.分为4组:小剂量化疗组、树突状细胞组、小剂量化疗+树突状细胞组、对照组,以BAX试剂盒检测肿瘤凋亡情况.在瘤体内注射树突状细胞,计算抑瘤率、特异性细胞毒性T淋巴细胞(CTL)的增殖及其对肿瘤细胞的特异性杀伤作用.结果 小剂量化疗能诱导肿瘤细胞凋亡,BAX 基因产物表达增多.注射侧抑瘤率小剂量化疗+DC组、小剂量化疗组、DC组分别为100%、67.22%和57.98%.对侧抑瘤率小剂量化疗+DC组、小剂量化疗组、DC组分别为87.58%、59.69%和48.24%.体内凋亡肿瘤细胞致敏的DC能显著刺激T淋巴细胞增殖,其诱导的CTL对MFC有显著的杀伤作用,在效靶比为40∶ 1、20∶ 1、10∶ 1和5∶ 1时72 h杀伤率分别为87.64%、70.32%、34.63%和13.87%.并能特异性杀伤小鼠前胃癌细胞MFC(P<0.01).结论 小剂量化疗的机制与肿瘤细胞凋亡及免疫促进有一定的相关.     

体外制备和增殖烟曲霉特异性T细胞的研究

目的体外制备和增殖烟曲霉特异性T淋巴细胞。方法从健康志愿者外周抗凝血中分离并体外扩增DC,利用加热灭活的烟曲霉孢子作为抗原,体外共孵育制备烟曲霉孢子负载的DC,进一步将此成熟DC与源自同一个体的去除了DC细胞的外周血细胞共培养,体外诱导并扩增烟曲霉特异性T淋巴细胞。应用ELISPOT(酶联免疫斑点)技术检测活化T细胞IFN-γ的分泌情况,流式细胞仪检测细胞因子胞内合成情况,并分析功能细胞的类型和比例。结果 ELISPOT分析显示:PBMC+DC+Conidia实验组IFN-γ分泌(87.33±1.33/4.0×105)高于其他对照组,具有统计学意义(P0.05)。细胞因子流式细胞仪分析显示:PBMC+DC+Conidia组中,2.76%的细胞分泌IFN-γ,其中1.61%为CD4+T细胞,与各对照组相比具有统计学意义(P0.05)。获得的烟曲霉特异性T细胞可以在体外可进行大量增殖。结论本文结果显示烟曲霉孢子在体外可以作为变应原诱导产生烟曲霉特异性CD4+T细胞介导的Th1型免疫反应,为未来制备和扩增烟曲霉特异性T细胞及过继免疫治疗侵袭性曲霉病提供实验基础。     

多表位肽抗原诱导特异性CTL抗慢性髓性白血病细胞的体外实验研究

目的：在应用基因工程技术人工表达获得多表位BCR-ABL融合蛋白的基础上,对该融合抗原在体外诱导对自血病细胞的特异性杀伤效应进行检测,探索慢性髓性自血病（CML）免疫治疗的新途径。方法：从外周血单个核细胞培养树突细胞（DC）,以BCR-ABL融合抗原脉冲刺激DC,诱导特异性细胞毒T淋巴细胞（CTL）产生;MTT法检测CTL对白血病靶细胞的特异性杀伤活性。结果：以BCR-ABL融合抗原刺激产生的CTL能特异性抑制b3a2＋的靶细胞生长,包括K562细胞（P〈0．01）和HIJA-A2＋／b3a2＋的CML原代细胞（P〈0．05）,而对HIA-A2-或b2a2＋靶细胞无明显抑制作用。结论：设计表达的多表位BCR-ABL融合抗原能在体外诱导特异性抗CML免疫反应,抑制b3a2＋自血病细胞生长,有望为进一步的体内实验奠定基础。     

DCIK细胞用于肺癌临床免疫治疗

观察细胞因子诱导的杀伤细胞(CIK 细胞)和同源树突状细胞(DC)共培养后,共培养细胞树突状细胞调节的细胞因子诱导的杀伤细胞(DCIK 细胞)体外细胞毒活性,并观察DCIK细胞治疗肺癌的近期临床疗效、免疫学活性及副反应.收录 12例确诊肺癌经标准治疗方案治疗的患者,取外周血分离单个核细胞(PBMC),体外诱导出DC和CIK细胞共培养后,观察DCIK细胞表型,用MTT法测体外细胞毒活性;当效靶比为20∶1、10∶1时,DCIK细胞体外细胞毒活性杀伤率分别为55%、46.2%.所有患者均接受一定剂量的 DCIK细胞过继免疫治疗,观察其近期临床疗效、免疫反应、不良反应.12例患者中完全缓解 1例,部分缓解4例,病情稳定1例,近期有效率为41.6%,疾病控制率为50%,病情进展共6例,其中死亡2例.与DCIK细胞回输前相比,患者CD4 、CD8 、CD56 均有明显的升高(P＜0.05),这表示可以诱导患者产生特异性的免疫反应.除两例患者出现一过性的发热外,其余患者基本无不良反应.DCIK细胞在肺癌免疫治疗中能诱导机体产生特异性的免疫反应,亦是新的杀伤肿瘤细胞的效应细胞,有较好的临床疗效.     

体内致敏的树突状细胞诱导特异性抗肿瘤免疫的基础研究

目的证实树突状细胞（dendritic cells,DC）可在体内通过吞噬凋亡肿瘤细胞获取抗原物质,探讨其在肿瘤免疫治疗中的意义.方法以615小鼠的前胃癌细胞株造模,在体外用rmGM-CSF和rmIL-4从荷瘤小鼠骨髓细胞分化、诱导未成熟树突状细胞.分为4组：小剂量化疗组、树突状细胞组、小剂量化疗＋树突状细胞组和对照组,以BAX试剂盒检测肿瘤细胞凋亡.在瘤体内注射树突状细胞,观察给药侧瘤体及对侧瘤体体积,生存期,和特异性细胞毒性T淋巴细胞（CTLs）对肿瘤细胞的特异性杀伤作用.结果小剂量化疗能诱导肿瘤细胞凋亡.小剂量化疗后瘤内应用树突状细胞,给药侧瘤体及对侧瘤体体积明显缩小（P＜0.05）,小鼠的生存率提高,体内凋亡肿瘤细胞致敏的DC诱导的CTL对MFC有显著的杀伤作用,在效靶比为40：1、20：1、10：1和5：1时72 h的杀伤率分别为87.64%、70.32%、34.63%和13.87%.并能特异性杀伤小鼠前胃癌细胞MFC（P＜0.01）.结论体外诱导分化的未成熟DC,能于体内捕获小剂量化疗诱导的凋亡肿瘤细胞所携带的肿瘤抗原,诱导机体特异性抗肿瘤免疫反应.     

Epstein-Barr病毒特异性T细胞对重组痘苗病毒表达LMP和EBNA2的靶细胞的识别

本文用EB病毒转化自体淋巴细胞所建立的类淋巴母细胞系(LCL),以及用EB病毒潜伏感染膜蛋白(LMP)基因和核蛋白-2(EBNA2)基因与痘苗病毒重组的重组病毒(Vac-LMP和Vac-EBNA2)感染的自身纤维母细胞,同时作为刺激细胞和靶细胞,以~(51)Cr释放法检测5例血清中EB病毒VCA—IgA抗体阳性者及1例阴性健康者外周血单个核细胞(PBMC)的特异性T细胞杀伤效应。结果表明,用自身LCL激活的EB病毒特异性T细胞杀伤效应高峰出现在第14～28天;参与杀伤性细胞免疫反应的T细胞亚群主要是T3、T8阳性的细胞毒性T细胞,其对靶细胞的识别及杀伤受HLA-I的限制。用重组牛痘病毒感染的纤维母细胞作靶细胞或刺激细胞,有1例供者可接受LMP,另1例可接受EBNA2的刺激,并对相应的靶细胞产生特异性T细胞杀伤反应,表明EB病毒-LMP和EBNA2可能既是EB病毒特异性T细胞的刺激抗原,又是其识别的靶抗原。     

生物肽-蛋氨酸脑啡肽增强树突状细胞抗肿瘤活性研究

采用反复冻融法制备Rac-1淋巴瘤细胞总抗原,与树突状细胞（DC2.4）共培养制备DC瘤苗;设置不同实验组,M组及RM组加入蛋氨酸脑啡肽（MENK）,研究MENK对DC瘤苗抗肿瘤细胞的杀伤活性影响。结果表明：MENK作用于DC瘤苗后,DC2.4形态上更趋向于成熟,且CD86、MHC-Ⅱ类分子表达水平与对照组相比较明显升高;DC2.4酸性磷酸酶（ACP）含量与对照组相比较明显减少而IL-12的分泌水平升高;同时,DC2.4诱导淋巴细胞增殖能力增强,且诱导活化的淋巴细胞对Rac-1淋巴瘤细胞的杀伤活性与对照组相比较明显增强。结果可见,MENK可明显促进特异性负载Rac-1淋巴瘤抗原的DC2.4的成熟,并增强特异性诱导活化的淋巴细胞对Rac-1淋巴瘤细胞的杀伤活性。     

Inhibition of tumor growth mediated by lymphocytes sensitized in vitro to a syngeneic murine teratocarcinoma 402AX

TerC, a cell line derived from a strain 129 teratocarcinoma 402AX, was used to sensitize syngeneic 129 (H-2bc) splenic lymphocytes in vitro. The effector cells generated inhibited in vitro growth of TerC as measured by an 125I-IUDR ost-labeling technique. It was also shown, with a modified Winn assay, that the sensitized cells were effective in preventing TerC growth in vivo. The effector lymphocyte was nonadherent to nylon wool was sensitive to anti-Thy-1.2 + C, and was phenotypically Ly 1-2+. The anti-TerC effector T lymphocytes were not functional in a 51Cr-release assay. However, this failure to lyse appears not to be due to some intrinsic membrane resistance since both BCG and ConA-activated killers were able to lyse TerC. The TerC-sensitized lymphocytes displayed no H-2 restriction and were able to growth inhibit in vitro a wide range of tumorigenic cell lines, e.g., P815 (H-2d), EL-4 (H-2b),Sal (H-2a), and BALB/c (H-2d) 3T12. Mouse blastocyst cell lines were also inhibited. BALB/c 3T3 and mouse fibroblast cell strains were not growth inhibited. Thus, it appears that oncofetal antigens expressed on TerC are capable of initiating a cell-mediated response and that these antigenic specificities are shared by many transformed cell lines.     

IgM induction in murine B hybridomas with Ia-restricted T cell clones: a monoclonal model for T and B cell interactions in antibody response

The mechanism of MHC-restricted T and B cell interactions in antibody response was studied with IgM-inducible B hybridomas and antigen-specific helper T cell clones. B hybridomas were prepared by fusion between splenic B cells from (CBA/N (H-2k) X BALB/c (H-2d)) F1 (NBF1) male mice and a B lymphoma cell line, M12.4.5. A B hybridoma clone, 1M70, which expressed I-Ad but not I-Ak determinants was chosen in the present study. IgM secretion was induced in 1M70 when it was cocultured with a "resting" KLH-specific and H-2d restricted helper T cell clone in the presence of KLH. A "resting" KLH-specific and H-2k restricted T cell clone did not induce IgM secretion in 1M70 even in the presence of KLH. However, when these KLH-specific T cell clones were activated by KLH and appropriate antigen presenting cells, both H-2d and H-2k restricted T cell clones induced IgM secretion in 1M70 even in the absence of KLH. A monoclonal anti-I-Ad antibody inhibited IgM secretion induced by a "resting" H-2d restricted T cell clone, but not by an "activated" T cell clone. These results indicated that T cell clones recognized antigens in the context of Ia molecules on B hybridomas in a MHC-restricted manner and were activated to produce B cell stimulatory factors which in turn acted on B hybridomas in a non-MHC-restricted manner and induced differentiation of B hybridomas into IgM secreting cells.     

Regulation of the in vitro presentation of minor lymphocyte stimulating determinants by major histocompatibility complex-encoded immune response genes

Activation of murine B lymphocytes in a splenocyte stimulator population with affinity-purified goat anti-mouse IgD (G alpha M delta) antibody was previously shown by this laboratory to enhance the presentation of strongly stimulatory major histocompatibility complex (MHC) and minor lymphocyte-stimulating (Mlsa,d) determinants in a primary mixed lymphocyte reaction. In the present study, the G alpha M delta treatment of murine splenocytes was employed to enhance the detection of the weakly stimulatory non-MHC Mlsc determinant in order to study the role the MHC might play as a restricting element for the recognition of these minor antigens in a primary mixed lymphocyte reaction. Indeed, enhanced T cell proliferation to Mlsc determinants presented on G alpha M delta-treated splenocytes was observed when the responder and activated H-2-compatible stimulator cell shared certain MHC haplotypes. High responsiveness was associated with the H-2a,k,j,p haplotypes, intermediate responsiveness was associated with the H-2f,g haplotypes and low responsiveness was associated with the H-2b,s haplotypes. (Low X high responder)F1 T cells preferentially responded to the Mlsc determinants presented on G alpha M delta-treated stimulator cells of the F1 or parental high responder H-2 haplotype. When mitomycin C instead of irradiation was used to inactivate normal (non-IgD-treated) splenocytes, a similar preferential response of T cells to Mlsc determinants presented on stimulator cells of a high responder H-2 haplotype was also observed. The inability of G alpha M delta-treated splenocytes of the low responder haplotype to elicit substantial levels of T cell proliferation across an Mlsc difference could not be attributed to the failure of these stimulator cells to become activated by the anti-Ig antibody. In addition, co-culture experiments could not identify the poor T cell response to Mlsc determinants presented on certain MHC haplotypes as being caused by the induction of nonspecific suppressor cells. Presentation of Mlsc determinants caused by transgene product complementation was detectable in F1 mice derived by crossing one parent that had the Mlsc non-MHC genes and a poorly permissive H-2 haplotype with a parent that expressed a permissive H-2 haplotype but lacked the Mlsc non-MHC genes.(ABSTRACT TRUNCATED AT 400 WORDS)     

Tumour-specific MHC-class-II-restricted responses after in vitro sensitization to synthetic peptides corresponding to gp100 and Annexin II eluted from melanoma cells

In a search for potentially tumour-specific MHC-class-II-restricted antigens, the immunogenicity of endogenous peptides that had been eluted from HLA-DR molecules of the human melanoma cell line FM3 (HLA-DRB1*02x, DRB1*0401) was tested in vitro. Two 16-mers representing gp100 positions 44–59, and annexin II positions 208–223 bound well to isolated DRB1*0401 molecules and are discussed here. HLA-DR-matched normal donors' T cells were cultured with peptide-pulsed artificial antigen-presenting cells (CHO cells cotransfected with genes for HLA-DRB1*0401 and CD80 and coexpressing high levels of both human molecules). Specific sensitization was achieved against both peptides, as measured in assays of autocrine proliferation and interleukin-2 secretion. Moreover, responses to native autologous melanoma cells but not to autologous B cells were also observed. In view of the expression of fas by the activated T cells and of fas ligand by the melanoma cells, blockade of potential fas/fas-ligand interactions was undertaken using monoclonal antibodies (mAb). The antagonistic fas-specific mAb M3, but not the fas agonist M33, caused a markedly enhanced T cell response to FM3 cells. These results demonstrate that synthetic peptide antigens are able to sensitize T cells in vitro for effective MHC-class-II-restricted recognition of melanoma cells. Received: 12 April 1998 / Accepted: 23 April 1998     

Granulocyte-macrophage colony-stimulating factor-based melanoma cell vaccines immunize syngeneic and allogeneic recipients via host dendritic cells

Subcutaneous injection of GM-CSF-expressing cancer cells into experimental animals results in protective cancer immunity. To delineate the mode of action of such vaccines, we used trinitrophenyl, the antigenic moiety of the contact allergen trinitrochlorobenzene, as surrogate Ag. Trinitrophenyl-derivatized bone marrow-derived dendritic cells were found to elicit a contact hypersensitivity response in syngeneic, but not in allogeneic recipients, compatible with their expected mode of direct Ag presentation. When expressing GM-CSF, haptenized M3 melanoma cells were also able to induce a contact hypersensitivity response but, in contrast to bone marrow-derived dendritic cells, not only in syngeneic but also in allogeneic recipients. This argues for a critical role of host APC. To identify their nature, we introduced the beta-galactosidase (betagal) gene into M3-GM cells. Their administration activated betagal-specific, L(d)-restricted CTL in syngeneic BALB/c mice. Evaluation of lymph nodes draining M3-GM-betagal injection sites revealed the presence of cells presenting the respective L(d)-binding betagal peptide epitope. Based on their capacity to activate betagal-specific CTL, they were identified as being CD11c(+) dendritic cells. These experiments provide a rational basis for the use of GM-CSF-based melanoma cell vaccines in an allogeneic setting.     

Generation of cytotoxic T cells specific for minor histocompatibility antigens by cross challenge in vitro with H-2 disparate adherent cells

Although it is well known that an H-2-restricted cytotoxic T cell response to minor histocompatibility antigens (MIHA) can be primed in vivo with H-2 disparate spleen cells, it has not been previously possible to induce cytotoxic T lymphocyte (CTL) precursors (CTLp) in vitro by this type of challenge. In this work, we demonstrate that the inability to cross challenge in vitro is due to the existence of inhibitory effects that can be obviated by cell fractionation, and to insufficient priming in vivo. BALB/c CTLp (H-2d) that have been repeatedly primed in vivo with B10.D2 can be challenged in vitro with C57BL10/J (H-2b) or B10.BR (H-2k)-adherent cells to generate CTL able to lyse B10.D2 (H-2d) target cells. The H-2 restriction properties of the cross-challenged CTL specific for MIHA were analyzed by using the technique of cold target competition. Within the limits of detection in bulk cultures, the entire response appeared to be H-2 unrestricted, whether the cross challenge was with intact C57BL10/J-adherent cells, or with membrane fragments of C57BL10/J presented by BALB/c adherent cells. The frequency of CTLp responsive to cross challenge was analyzed by limiting dilution, with cold target competition at each cell number to establish the restriction properties of the MIHA-specific CTL induced. We were able to detect two subsets of H-2-unrestricted CTLp responsive to intact C57BL10/J-adherent cells; one present at high frequency (1/250 T cells) and subject to suppressive effects at high cell number, and a second present at lower frequency (1/9800 T cells). There appeared to be a relatively infrequent subset of H-2-restricted CTLp as well (1/52,500 T cells). The frequency of CTLp responsive to cross challenge is of comparable magnitude to the frequency of H-2-restricted CTLp responsive to H-2-matched cells bearing MIHA. These observations are discussed in relationship to immunodominance and clonal dominance effects in the response to MIHA.     

含EBV-LMP2基因重组腺病毒修饰的树突状细胞疫苗体内外特异性抗瘤作用的研究

鼻咽癌(NPC)在东南亚地区,尤其在我国南方地区发病率高达40／10万～60／10万。Epstein—Barrvirus(EBV)在鼻咽癌的病因学中有着十分重要的作用,在肿瘤细胞中该病毒的存在为以CTL为基础的免疫治疗提供了一个潜在靶位。过继性EBV特异性CTL,成功地治疗了骨髓移植受者体内出现的来自捐献者的免疫增生性B细胞淋巴瘤的研究,显示了这种方法的可行性。LMP2已经被证实可以诱发较强的特异性细胞免疫反应,而且也确定了很多CTL表位。目前许多关于EBV相关肿瘤治疗的研究都是针对LMP2的。树突状细胞(DC)是人体内最强大的抗原呈递细胞(APC),在肿瘤的免疫治疗中有着重要的作用。     

Antitumor Activity of T Cells Generated from Lymph Nodes Draining the SEA-expressing Murine B16 Melanoma and Secondarily Activated with Dendritic Cells

The successful use of tumor-draining lymph nodes (TDLN) as a source of effector cells for cancer immunotherapy depends largely on the immunogenicity of the tumor drained by the lymph nodes as well as the methods for secondary in vitro T cell activation and expansion. We transferred the bacterial superantigen staphylococcal enterotoxin A (SEA) gene into B16 murine melanoma tumor cells, and used them to induce TDLN (SEA TDLN) in syngeneic hosts. Wild-type (wt) TDLN induced by parental B16 tumor was used as a control. In vitro, SEA TDLN cells proliferated more vigorously, produced more IFNγ and demonstrated higher CTL activity than wt TDLN cells when activated with anti-CD3/anti-CD28/IL-2. In vivo, SEA TDLN cells mediated tumor eradication more effectively than similarly activated wt TDLN cells (p<0.01). Furthermore, use of dendritic cells (DC) plus tumor antigen in vitro in addition to anti-CD3/anti-CD28/IL-2 stimulation further amplified the immune function and therapeutic efficacy of SEA TDLN cells. DC-stimulated SEA TDLN cells eliminated nearly 90% of the pulmonary metastasis in mice bearing established B16 melanoma micrometastases. These results indicate that enforced expression of superantigen SEA in poorly immunogenic tumor cells can enhance their immunogenicity as a vaccine in vivo. The combined use of genetically modified tumor cells as vaccine to induce TDLN followed by secondary stimulation using antigen-presenting cells and tumor antigen in a sequential immunization/activation procedure may represent a unique method to generate more potent effector T cells for adoptive immunotherapy of cancer.     

Antigen-presenting T cells. I. Class I alloantigen (bm1)-bearing T lymphoblasts efficiently stimulate a primary clonal response of Lyt-2+ cytotoxic lymphocyte precursors of B6 origin

The cytotoxic response of splenic Lyt-2+ T cells to class I H-2 alloantigen-bearing stimulator cells was analyzed under limiting dilution conditions. One of 50 to one of 200 nylon wool-nonadherent (FACS-purified), small Lyt-2+ spleen cells of B6 origin gave rise in vitro to a cytotoxic T lymphocyte clone that specifically lysed targets bearing bm1 alloantigen. This population of alloantigen-specific cytotoxic lymphocyte precursors (CLP) was activated by different types of bm1 stimulator cells with different efficiency: 2 X 10(5) nonfractionated spleen cells, 5000 normal peritoneal cells, 400 to 10(4) L3T4+ helper T blasts, or 2000 to 10(4) Lyt-2+ T blasts induced clonal growth of this CLP pool. Irradiated or mitomycin-treated small (L3T4+ or Lyt-2+) bm1-derived T cells were inefficient stimulator cells for this response. Supplementation of culture medium with (recombinant) interleukin 2 was necessary and sufficient to support clonal development of alloantigen-triggered CLP in the presence of allogeneic T blasts. Under these limiting dilution conditions, we observed comparable cloning efficiencies for (wild-type) Kb-allospecific splenic Lyt-2+ CLP from bm1 mice generated in response to either irradiated B6 spleen cells or inactivated B6-derived T cell lines (EL4 and RBL-5 lymphoma cells). The data indicate that normal T lymphoblasts as well as tumor T cell lines stimulate clonal development in vitro of class I H-2-allospecific cytotoxic T lymphocytes in the presence of interleukin 2.