CD4+ T cells support polyfunctionality of cytotoxic CD8+ T cells with memory potential in immunological control of tumor

Polyfunctionality/multifunctionality of effector T cells at the single cell level has been shown as an important parameter to predict the quality of T cell response and immunological control of infectious disease and malignancy. However, the fate of polyfunctional CD8⁺ CTLs and the factors that control the polyfunctionality of T cells remain largely unknown. Here we show that the acquisition of polyfunctionality on the initial stimulation is a sensitive immune correlate of CTL survival and memory formation. CD8⁺ T cells with high polyfunctionality, assessed with γ‐interferon and tumor necrosis factor‐α production and surface mobilization of the degranulation marker CD107a, showed enhanced Bcl‐2 expression, low apoptosis, and increased CD127^highKLRG1^low memory precursor phenotype. Consistent with these observations, CD8⁺ T cells were found to acquire high frequency of cells with polyfunctionality when stimulated in conditions known to enhance memory formation, such as the presence of CD4⁺ T cells, interleukin (IL)‐2, or IL‐21. Utilizing T‐cell receptor (TCR) transgenic mouse‐derived CD8⁺ T cells that express a TCR specific for a tumor‐derived neoantigen, we showed that polyfunctional tumor‐specific CTLs generated in the presence of CD4⁺ T cells showed long persistence in vivo and induced enhanced tumor regression when adoptively transferred into mice with progressing tumor. Acquisition of polyfunctionality thus impacts CTL survival and memory formation associated with immunological control of tumor.     

Elimination of regulatory T cells is essential for an effective vaccination with tumor lysate-pulsed dendritic cells in a murine glioma model

Both melanoma and glioma cells are of neuroectodermal origin and share common tumor associated antigens. In this article, we report that the melanocyte differentiation antigen TRP2 (tyrosinase-related protein 2) is not predominantly involved in the tumor rejection of a syngeneic murine glioma. Although GL261 glioma cells endogenously expressed TRP2 and were lysed by TRP2 specific cytotoxic T cells (CTLs) in vitro, vaccinations with TRP2 peptide-pulsed dendritic cells (DCs) could only induce minor antiglioma responses in a prophylactic setting and failed to work in a stringent setting where vaccine and tumor were administered on the same day. Further analysis revealed that TRP2 is not recognized by bulk CTLs after depletion of regulatory T cells which results in tumor rejections in vivo. In contrast to TRP2 peptide-pulsed DC, tumor lysate-pulsed DCs were more potent as a vaccine and completely protected mice from tumor outgrowth in a prophylactic setting. However, the vaccine efficacy of tumor lysate-pulsed DC was not sufficient to prevent the tumor outgrowth when tumors were inoculated the same day. In this case, Treg depletion before vaccination was essential to boost antiglioma immune responses leading to the rejection of 80% of the mice and long-term immunity. Therefore, we conclude that counteracting the immunosuppressive glioma tumor environment via depletion of regulatory T cells is a prerequisite for successful eradication of gliomas after targeting multiple tumor antigens by using tumor lysate-pulsed DCs as a vaccine in a more stringent setting.     

IL-12与IL-18联合刺激对树突状细胞分泌的exosome活性的影响

目的:观察IL-12与IL-18联合刺激对树突状细胞(dendritic cell,DC)分泌的exosome(DC derived exosome,Dex)活性的影响,为探索高效的exosome肿瘤疫苗奠定基础。方法:取正常健康人外周血单个核细胞诱导培养DCs,分别以IL-12、IL-18或IL-12+IL-18联合刺激DC,并设空白对照组、T细胞对照组,分别提取各组的Dex,Western blotting检测Dex中HLA-DR、CD83的表达,流式细胞仪检测CD54、CD80及CD86的表达;MTT法检测Dex刺激T细胞增殖的作用,ELISA法测定T细胞IFN-γ的分泌量。结果:IL-12、IL-18、联合组、空白组的Dex中均有HLA-DR、CD83蛋白表达;联合组Dex的CD54(323.67±44.06 vs 246.17±31.91、236.33±33.87、167.67±28.73,P<0.05)、CD80(406.37±39.18 vs 331.67±36.15、335.67±41.38、260.00±35.58,P<0.05)及CD86(390.50±38.06 vs 314.33±36.64、319.00±33.10、246.83±30.55,P<0.05)表达均高于IL-12组、IL-18组及空白组;联合组刺激T细胞增殖高于IL-12组、IL-18组及空白组、T细胞组(1.98±0.31vs 1.55±0.23、1.57±0.21、1.10±0.18、0.53±0.09,P<0.05);联合组刺激T细胞分泌IFN-γ水平高于IL-12组、IL-18组及空白组、T细胞组(436.67±61.80 vs 295.04±40.25、358.18±55.77、225.00±36.44、139.50±17.63,P<0.05)。结论:IL-12与IL-18联合刺激能增加Dex表达CD54、CD80及CD86,促进Dex刺激的T细胞的增殖及其IFN-γ的分泌。     

肿瘤抗原致敏树突状细胞疫苗治疗晚期恶性肿瘤的临床观察

目的:观察肿瘤抗原致敏人树突状细胞(dendritic cell,DC)疫苗治疗各类晚期恶性肿瘤的不良反应,初步观察其治疗疗效。方法:91例非小细胞肺癌、结直肠癌、恶性黑素瘤、肾癌、乳腺癌等晚期恶性肿瘤患者入组,均符合试验的纳入组及排除标准,签署知情同意书,并报医院伦理委员会审查批准。患者单采外周血单核细胞体外培育成DC,用抗原致敏后制备成DC疫苗回输,每周回输1次,3次定义为1个周期。结果:91例患者共接受96个周期疫苗治疗;不良反应主要表现为寒战、发热、肌肉酸痛、皮肤瘙痒、胸闷及一过性全身无力,大部分为自限性;76例进行疗效评价,无完全缓解(complete remission,CR)及部分缓解(partial remission,PR)病例,治疗后稳定(stable disease,SD)31例,进展(progression disease,PD)45例,临床获益率40.8%;85例患者获得随访资料,患者中位达进展时间(median time to progression,mTTP)为2.6个月,生存时间为0.9~30.6个月,中位生存时间为4.5个月,1年生存率为9.2%。结论:肿瘤抗原致敏人DC疫苗治疗各类晚期恶性肿瘤耐受性良好,亦可见临床获益,疫苗临床应用方法有待进一步探讨。     

Immunization with tumor-derived ER chaperone grp170 elicits tumor-specific CD8+ T-cell responses and reduces pulmonary metastatic disease

Glucose-regulated protein (grp) 170 is a molecular chaperone localized in endoplasmic reticulum (ER), which has been demonstrated to interact with the peptides translocated by transporter associated with antigen presentation (TAP). In our study, we have evaluated the therapeutic efficacy of tumor-derived grp170 against the highly metastatic and poorly immunogenic murine melanoma B16F10. Immunization of mice with grp170 preparations from autologous tumor significantly delayed progression of the primary cancer and reduced established pulmonary metastases, which was associated with the prolonged survival of metastases-bearing mice. However, grp170 from normal liver or antigenically distinct tumor failed to exhibit therapeutic effect. In addition, tumor-derived grp170 elicited a potent cytotoxic T-lymphocyte response specific for B16F10 tumor, which correlates with in vivo protective effects. Adoptive transfer of splenocytes obtained from B16F10-grp170-primed animals remarkably suppressed pulmonary metastases. Depletion of either CD4(+) or CD8(+) T cells in priming phase significantly abrogated the tumor immunity induced by the B16F10-grp170. However, the vaccine activity was intact when CD4(+), not CD8(+), T cells were depleted in effector phase. It suggests that CD4(+) T helper cells play an important role in the generation of effective antitumor response, whereas CD8(+) T cells are predominantly involved in direct killing of tumor cells. These observations have strong clinical implications for using tumor-derived grp170 as a therapeutic vaccine against metastatic diseases.     

Induction of tumour-specific CD8(+) cytotoxic T lymphocytes by tumour lysate-pulsed autologous dendritic cells in patients with uterine serous papillary cancer

Uterine serous papillary carcinoma is a highly aggressive variant of endometrial cancer histologically similar to high grade ovarian cancer. Unlike ovarian cancer, however, it is a chemoresistant disease from onset, with responses to combined cisplatinum-based chemotherapy in the order of 20% and an extremely poor prognosis. In this study, we demonstrate that tumour lysate-pulsed autologous dendritic cells can elicit a specific CD8(+) cytotoxic T lymphocyte response against autologous tumour target cells in three patients with uterine serous papillary cancer. CTL from patients 1 and 2 expressed strong cytolytic activity against autologous tumour cells, did not lyse autologous lymphoblasts or autologous EBV-transformed cell lines, and were variably cytotoxic against the NK-sensitive cell line K-562. Patient 3 CD8(+) T cells expressed a modest but reproducible cytotoxicity against autologous tumour cells only at the time of the first priming. Further priming attempts with PBL collected from patient 3 after tumour progression in the lumboaortic lymph nodes were unsuccessful. Cytotoxicity against autologous tumour cells could be significantly inhibited by anti-HLA class I (W6/32) and anti-LFA-1 MAbs. Highly cytotoxic CD8(+) T cells from patients 1 and 2 showed a heterogeneous CD56 expression while CD56 was not expressed by non-cytotoxic CD8(+) T cells from patient 3. Using two colour flow cytometric analysis of intracellular cytokine expression at the single cell level, a striking dominance of IFN-gamma expressors was detectable in CTL populations of patients 1 and 2 while in patient 3 a dominant population of CD8(+) T cells expressing IL-4 and IL-10 was consistently detected. Taken together, these data demonstrate that tumour lysate-pulsed DC can be an effective tool in inducing uterine serous papillary cancer-specific CD8(+) CTL able to kill autologous tumour cells in vitro. However, high levels of tumour specific tolerance in some patients may impose a significant barrier to therapeutic vaccination. These results may have important implications for the treatment in the adjuvant setting of uterine serous papillary cancer patients with active or adoptive immunotherapy.     

Recombinant E. coli efficiently delivers antigen and maturation signals to human dendritic cells: presentation of MART1 to CD8+ T cells

The generation of tumour-specific cytotoxic T-lymphocyte (CTL) responses is the primary focus in the design of immunotherapeutic cancer vaccines. We have recently demonstrated generation of ovalbumin (OVA)-specific CTLs and tumour-protection in a murine tumour model using vaccination with dendritic cells (DCs) pulsed with E. coli expressing listeriolysin O (LLO) and OVA as a model antigen. In this system paraformaldehyde fixation of E. coli/LLO provided an additional safety feature without compromising vaccine efficacy. We therefore reasoned that paraformaldehyde-fixed recombinant E. coli expressing LLO would be an efficient vehicle for the delivery of human tumour antigens to human DCs. In the present study, we demonstrate that fixed E. coli expressing LLO are taken up efficiently by human monocyte-derived DCs (MoDCs) with minimal toxicity. As a consequence of the interaction with bacteria, human DCs undergo marked phenotypic and functional maturation. Furthermore, we show that fixed E. coli/LLO expressing the well-characterised human melanoma antigen, MART1, efficiently deliver the HLA-A2-restricted MART1(27-35) epitope for processing and presentation on human MoDCs, suggesting the potential of this system as a novel strategy for human tumour immunotherapy.     

Surgery and adjuvant dendritic cell-based tumour vaccination for patients with relapsed malignant glioma, a feasibility study

Patients with relapsed malignant glioma have a poor prognosis. We developed a strategy of vaccination using autologous mature dendritic cells loaded with autologous tumour homogenate. In total, 12 patients with a median age of 36 years (range: 11-78) were treated. All had relapsing malignant glioma. After surgery, vaccines were given at weeks 1 and 3, and later every 4 weeks. A median of 5 (range: 2-7) vaccines was given. There were no serious adverse events except in one patient with gross residual tumour prior to vaccination, who repetitively developed vaccine-related peritumoral oedema. Minor toxicities were recorded in four out of 12 patients. In six patients with postoperative residual tumour, vaccination induced one stable disease during 8 weeks, and one partial response. Two of six patients with complete resection are in CCR for 3 years. Tumour vaccination for patients with relapsed malignant glioma is feasible and likely beneficial for patients with minimal residual tumour burden.     

Prostate stem cell antigen: Identification of immunogenic peptides and assessment of reactive CD8+ T cells in prostate cancer patients

Identification of TAAs recognized by CD8(+) CTLs paved the way for new concepts in cancer therapy. In view of the heterogeneity of tumors and their diverse escape mechanisms, CTL-based cancer therapy largely depends on an appropriate number of TAAs. In prostate cancer, the number of antigens defined as suitable targets of CTLs remains rather limited. PSCA is widely distributed in prostate cancer. In this report, we define immunogenic peptides of PSCA which are recognized by circulating CD8(+) T cells from prostate cancer patients and able to activate CTLs in vitro. Screening the amino acid sequence of PSCA for peptides containing a binding motif for HLA-A*0201 resulted in 8 candidate peptides. Specificity and affinity of peptide binding were verified in a competition assay. Frequencies of CD8(+) T lymphocytes reactive against selected epitopes were determined in the blood of prostate cancer patients using the ELISPOT assay. Increased frequencies were revealed for CD8(+) T cells recognizing the peptides ALQPGTALL and AILALLPAL. CTLs from prostate cancer patients were raised against these 2 peptides in vitro when presented by autologous DCs. They specifically recognized peptide-pulsed T2 target cells and prostate cancer cells that were HLA-A*0201- and PSCA-positive, indicating that these peptides were naturally generated by tumor cells. These data suggest that PSCA is a promising target for the immunotherapy of prostate cancer.     

Targeting Tumors with IL-10 Prevents Dendritic Cell-Mediated CD8+ T Cell Apoptosis

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Induction of peptide-specific immune response in patients with primary malignant melanoma of the esophagus after immunotherapy using dendritic cells pulsed with MAGE peptides

Primary malignant melanoma of the esophagus (PMME) is a very rare disease with an extremely poor prognosis. Surgery is currently considered its best treatment, while any other measures are ineffective. We studied the effect of active specific immunotherapy using monocyte-derived dendritic cells (DCs) pulsed with the epitope peptides of melanoma-associated antigens (MAGE-1, MAGE-3) in patients with PMME after surgery, for the first time. The patient received passive immunotherapy with lymphokine-activated killer cells concomitantly. Two HLA-A24-positive patients with PMME were treated. Both patients initially received radical esophagectomy with regional lymphadenectomy, followed by adjuvant chemotherapy with dacarbazine, nimustine, vincristine and interferon-alpha. In the case 1 patient, active specific immunotherapy was used to treat a large abdominal lymph node metastasis that became obvious 21 months after surgery. The disease remained stable for 5 months, and the patient survived for 12 months after the initiation of immunotherapy. In the case 2 patient, immunotherapy was tried as post-operative adjuvant treatment after adjuvant chemotherapy. There was no tumor recurrence for 16 months after the immunotherapy. As of 49 months after esophagectomy, the patient is still alive. In both patients, the ability of peripheral lymphocytes to produce IFN-gamma in vitro in response to peptide stimulation was significantly enhanced and delayed-type hypersensitivity skin test response to MAGE-3 peptide was turned positive after immunotherapy. In conclusion, active specific immunotherapy for PMME with the use of DCs and MAGE peptides was safe and capable of inducing peptide-specific immune responses. This case report warrants further clinical evaluation of this immunotherapy for PMME.     

Exosome-loaded dendritic cells elicit tumor-specific CD8<Superscript>+</Superscript> cytotoxic T cells in patients with glioma

In this study, we demonstrate that tumor-derived exosome-loaded dendritic cells can elicit a specific CD8⁺ cytotoxic T-lymphocyte (CTL) response against autologous tumor cells in patients with malignant glioma. Exosomes were purified by ultrafiltration centrifugation and sucrose gradient ultracentrifugation. Exosomes had antigen-presenting molecules (MHC-I, HSP70), tumor antigen (MAGE-1) and adherent molecule (ICAM-1). After incubation with exosomes, the dendritic cells (DCs) could activate the T lymphocytes to become glioma-specialized CTL. The CTL had vigorous cytotoxicity to glioma cells as opposed to autologous lymphoblast cells. These data demonstrate that tumor exosome-loaded DC can be an effective tool in inducing glioma-specific CD8⁺ CTLs able to kill autologous glioma cells in vitro. In conclusion, exosomes are a natural and new source of tumor-rejection antigens, opening up new avenues for immunization against glioma.     

Vaccination with tumor lysate-pulsed dendritic cells elicits antigen-specific, cytotoxic T-cells in patients with malignant glioma

The primary goal of this Phase I study was to assess the safety and bioactivity of tumor lysate-pulsed dendritic cell (DC) vaccination to treat patients with glioblastoma multiforme and anaplastic astrocytoma. Adverse events, survival, and cytotoxicity against autologous tumor and tumor-associated antigens were measured. Fourteen patients were thrice vaccinated 2 weeks apart with autologous DCs pulsed with tumor lysate. Peripheral blood mononuclear cells were differentiated into phenotypically and functionally confirmed DCs. Vaccination with tumor lysate-pulsed DCs was safe, and no evidence of autoimmune disease was noted. Ten patients were tested for the development of cytotoxicity through a quantitative PCR-based assay. Six of 10 patients demonstrated robust systemic cytotoxicity as demonstrated by IFN-gamma expression by peripheral blood mononuclear cells in response to tumor lysate after vaccination. Using HLA-restricted tetramer staining, we identified a significant expansion in CD8+ antigen-specific T-cell clones against one or more of tumor-associated antigens MAGE-1, gp100, and HER-2 after DC vaccination in four of nine patients. A significant CD8+ T-cell infiltrate was noted intratumorally in three of six patients who underwent reoperation. The median survival for patients with recurrent glioblastoma multiforme in this study (n = 8) was 133 weeks. This Phase I study demonstrated the feasibility, safety, and bioactivity of an autologous tumor lysate-pulsed DC vaccine for patients with malignant glioma. We demonstrate for the first time the ability of an active immunotherapy strategy to generate antigen-specific cytotoxicity in brain tumor patients.     

Role of IL-2, IL-4 and IL-6 in the growth and differentiation of tumor-specific CD4+ T helper and CD8+ T cytotoxic cells

We have earlier observed that 1,3-bis (2-chloroethyl)-1-nitrosourea (BCNU), a chemotherapeutic drug, cured 90-100% of mice bearing a syngeneic Ia- T-cell lymphoma (LSA) and furthermore, 100% of the BCNU-cured mice could reject homologous tumor rechallenge. In the present study, purified CD4+ and CD8+ T cells isolated from BCNU-cured mice were used to investigate the mechanism by which such T cells recognized and responded to the tumor-specific antigens. The responsiveness of CD4+ T cells to LSA was dependent on processing and presentation of tumor-specific antigens by syngenic Ia+ splenic antigen-presenting cells (APC). Such activated CD4+ T cells endogenously produced IL-2 but not IL-4 and only IL-2 acted as an autocrine growth factor inasmuch as anti-IL-2 receptor antibodies but not anti-IL-4 antibodies inhibited the CD4+ T cell proliferation. In contrast, the CD8+ T cells failed to produce endogenous growth factors when stimulated with LSA alone or with LSA plus APC, and therefore failed to proliferate. However, in the presence of exogenous recombinant IL-2 (rIL-2), CD8+ T cells could proliferate directly in response to LSA-stimulation, even in the absence of APC. Addition of exogenous rIL-4 alone to cultures induced CD4+ but not CD8+ T cells to proliferate. However, rIL-4 in the presence of rIL-2, could synergize and induce tumor-specific proliferation of CD8+ cells. These data suggested that for IL-4 to act as a T-cell growth factor, the presence of IL-2 was essential, either in the form of endogenously secreted IL-2 (CD4+ T cells) or exogenous IL-2 (for CD8+ T cells). In contrast to rIL-2 and rIL-4, rIL-6 failed to induce growth when used alone or in combination with rIL-2 or rIL-4. Furthermore, when tested individually, only rIL-2 but not rIL-4 or rIL-6 could support the cytotoxic differentiation of CD8+ T cells. The present study suggests that the early events in responsiveness to LSA tumor may involve activation of the IL-2-producing Th1 subpopulation of CD4+ helper cells which in turn activate IL-2 dependent CD8+ cytotoxic T cells. IL-4 if produced subsequently, may act synergistically with IL-2 to promote the growth of CD4+ and CD8+ T cells.     

阻断DKK1通过促进CD4+ T细胞Th1型极化改善抗肿瘤免疫应答

目的：探讨恶性肿瘤中Dickkopf-1（DKK1）表达对CD4+ T细胞极化的影响及其作为肿瘤免疫治疗靶点的潜在价值。 方法：利用生物信息学方法分析DKK1在多种类型肿瘤组织和癌旁组织中的表达水平,分析DKK1表达与肿瘤患者预后及肿瘤 微环境免疫浸润间的相关性。利用流式细胞术检测DKK1蛋白对CD4+ T细胞表型变化的影响。构建黑色素瘤B16F10细胞小鼠 皮下移植瘤模型,观察阻断DKK1对小鼠移植瘤生长和移植瘤组织中免疫细胞浸润与表型的影响。结果：DKK1 mRNA表达水 平在多种肿瘤组织中显著高于癌旁组织,DKK1高表达与多数肿瘤患者的不良预后相关且在多数肿瘤中DKK1对CD4+ T细胞抗 肿瘤免疫应答功能有重要负性调节作用（P<0.05或P<0.01）。流式细胞术检测结果显示 ,DKK1 蛋白刺激可显著降低CD4+ T细 胞中T-bet、IFN-γ 及 CD107a 表达水平（均P<0.01）。在小鼠皮下黑色素瘤模型中发现,阻断DKK1可以显著抑制小鼠移植瘤的生长 （P<0.01）,有效改善抗肿瘤免疫应答,表现为 Th1 细胞（T-bet + CD4+ ）占比显著升高（P<0.001）,效应性 CD8+ T 细胞（CD44+ CD62L- ）占比显著升高（P<0.01）,Th2细胞（GATA3+ CD4+ ）与Treg细胞占比显著下降（均P<0.01）。结论：阻断DKK1可有效促进 CD4+ T细胞向Th1型极化,DKK1具有作为肿瘤免疫治疗靶点的潜在价值。     

结肠癌患者化疗/热化疗前后CD4+CD25+T细胞和CTL变化

背景与目的:化疗是内科治疗结肠癌的主要方法之一,热化疗改善患者机体免疫状态的机制尚不清楚.本研究通过观察结肠癌患者化疗/热化疗前后CD4+CD25+调节性T(Treg)细胞及细胞毒T淋巴细胞功能的变化,探讨其临床意义.方法:入选结肠癌Ⅲ期术后患者60例,其中热化疗组30例,以单纯化疗组30例为对照组,收集患者治疗前后外周血,采用流式细胞术检测治疗前后外周血淋巴细胞中CD4+CD25+Treg细胞的表达,并检测患者CTL细胞杀伤功能.结果:(1)结肠癌患者单纯化疗组化疗前CD4+CD25+Treg细胞表达为19±9,化疗后为19±7,差异无统计学意义(F=0.026,P＞0.05);热化疗组化疗前CD4+CD25+Treg细胞表达为19±5,化疗后为14±4,差异有统计学意义(F=2.198,P＜0.05);(2)结肠癌患者单纯化疗组化疗前细胞毒T淋巴细胞(cytotoxic T lymphocytes,CTL)为10±3,化疗后为15±5,差异有统计学意义(F=187.801,P＜0.05);热化疗组化疗前CTL为12±3,化疗后CTL为18±5,两组比较差异有统计学意义(F=236.097,P＜0.05).即化疗组治疗前后CD4+CD25+Treg细胞变化不明显,而化疗联合热疗组治疗后CD4+CD25+Treg细胞水平显著降低.两组结肠癌患者治疗后CTL细胞杀伤功能均明显增强,以热化疗组增强更明显.结论:热化疗可明显改善结肠癌患者的免疫抑制状态,增强患者的细胞毒T淋巴细胞的功能.化疗联合热疗可提高患者疗效和预后.     

Generation of CD8+ cytotoxic T lymphocytes against breast cancer cells by stimulation with mammaglobin-A-pulsed dendritic cells

Mammaglobin-A is exclusively expressed by breast cancer cells. Thus, mammaglobin-A-specific T cell immune responses may be useful for the design of new breast cancer-specific immunotherapies. We show herein that CD8+ T cells generated against recombinant mammaglobin-A-pulsed dendritic cells display a marked cytotoxic activity against mammaglobin-A-positive breast cancer cell lines. This study indicates the immunotherapeutic potential of this novel antigen for the treatment of breast cancer.     

Vaccination with tumor cell lysate-pulsed dendritic cells augments the effect of IFN-beta gene therapy for malignant glioma in an experimental mouse intracranial glioma

Interferon-beta (IFN-beta) has been used as an antitumor drug against human glioma, melanoma and medulloblastoma since the 1980s. Recently, we developed a new gene therapy using the IFN-beta gene against malignant gliomas and then began clinical trials in 2000. Since stimulation of immune system was one mechanism of antitumor effect induced by IFN-beta gene therapy, we hypothesized that combination of IFN-beta gene therapy with immunotherapy might increase its effectiveness. In the present study, we tested whether combination therapy with IFN-beta gene therapy and immunotherapy using tumor cell lysate-pulsed dendritic cells (DCs) would increase the efficacy of IFN-beta gene therapy. In an experimental mouse intracranial glioma (GL261), which cannot be cured by either IFN-beta gene therapy or DC immunotherapy alone, IFN-beta gene therapy following DC immunotherapy resulted in a significant prolongation in survival of the mice. Moreover, when this combination was performed twice, 50% of treated mice survived longer than 100 days. Considering these results, this combination therapy may be one promising candidate for glioma therapy in the near future.     

A parathyroid-hormone-related-protein (PTH-rP)-specific cytotoxic T cell response induced by in vitro stimulation of tumour-infiltrating lymphocytes derived from prostate cancer metastases, with epitope peptide-loaded autologous dendritic cells and low-dose IL-2.

Bone metastases are one of the most common events in patients with prostate carcinoma. PTH-rP, a protein produced by prostate carcinoma and other epithelial cancers, is a key agent for the development of bone metastases. A PTH-rP-derived peptide, designated PTR-4 was identified, which is capable to bind HLA-A2.1 molecules and to generate PTH-rP-specific cytotoxic T cell (CTL) lines from healthy HLA-A2.1(+) individual peripheral-blood-mononuclear-cells (PBMC). In this model, we investigated the in vitro possibility of generating an efficient PTH-rP specific CTL response by cyclical stimulations with IL-2 and PTR-4 peptide-pulsed autologous dendritic cells (DC), of HLA-A2.1(+) tumour infiltrating lymphocytes (TIL) derived from a patient with metastatic prostate carcinoma. A T cell line generated in this way (called TM-PTR-4) had a CD3(+), CD5(+), CD4(-), CD8(+), CD45(Ro+), CD56(-) immunophenotype and a HLA-A2.1 restricted cytotoxic activity to PTR-4-peptide pulsed CIR-A2 (HLA-A2.1(+)) target cells, PTH-rP(+)/HLA-A2.1(+) CIR-A2 transfected with PTH-rP gene, prostate carcinoma LNCaP cells, and autologous metastatic prostate cancer cells (M-CaP). These lymphocytes were not cytotoxic to HLA-A2.1(+) targets not producing PTH-rP, such as peptide-unpulsed CIR-A2 and colon carcinoma SW-1463, cell lines. Our results provide evidence that PTR-4 peptide-pulsed autologous DC may break the tolerance of human TIL against the autologous tumour by inducing a PTH-rP-specific CTL immune reaction. In conclusion PTR-4 peptide-pulsed autologous DC may be a promising approach for vaccine-therapy and antigen-specific CTL adoptive immunotherapy of hormone-resistant prostrate cancer.