Protective effects of a protein-bound polysaccharide, PSK, against Candida albicans infection in syngeneic tumor-bearing mice via Th1 cell functions

We investigated the effects of a protein-bound polysaccharide, PSK, on the resistance of tumor-bearing mice against Candida albicans infection. In BALB/c mice that had received subcutaneous (sc) transplantation of fibrosarcoma Meth A, viable fungal counts were increased in the kidney and the mean survival period was shortened after challenge with C. albicans, compared with healthy mice. Oral administration of PSK to such mice resulted in a significant decrease of viable fungal counts and a prolongation of the mean survival period. The ratio of CD4-positive T cells in the spleen was decreased in noninfected tumor-bearing mice and the decrease was prevented by PSK, although in vitro anticandida activities of phagocytes were not significantly affected by tumor burden or PSK. Further, intracellular interferon (IFN)-gamma productivity was enhanced and the number of IFN-gamma-producing CD4-positive T cells was enhanced by PSK. PSK enhanced the gene expression of interleukin (IL)-12 and IFN-gamma in the spleen of tumor-bearing mice inoculated with C. albicans. Treatments with anti-IL-12 or anti-IFN-gamma antibody reduced the anti-infectious effects of PSK. These findings suggest that the protective effect of PSK on sublethal inoculation with C. albicans in tumor-bearing mice is possibly mediated by Th1 cell functions.     

Effect of Krestin (PSK) on the induction of IL-2 activated killer cells.

The effects of Krestin (PSK) on the generation of lymphokine-activated killer (LAK) cells were examined in tumor-bearing mice. BALB/c mice were inoculated subcutaneously with methylcholanthrene-induced fibrosarcoma (Meth A) cells, and PSK was administered intraperitoneally every other day. The reduced LAK activity in tumor-bearing mice was restored by the administration of PSK. Since involvement of the humoral immunosuppressive factor in the impairment of LAK activity has been suggested, the effect of PSK on the impaired LAK activity in the presence of an immunosuppressive factor isolated from the ascites of X5563 (plasmacytoma)-inoculated mice was examined. The activity reduced by the immunosuppressive factor in an in vitro induction of LAK was restored by incubation with PSK. The antimetastatic effect of IL-2 was also augmented by its combined use with PSK. The data provide a rational basis for using PSK in combination with recombinant IL-2 in cancer immunotherapy.     

Intensification of antitumor effect by T helper 1-dominant adoptive immunogene therapy for advanced orthotopic colon cancer.

PURPOSE: T helper (Th) 1/Th2 balance, controlled by Th1 or Th2 cells producing cytokines, plays important roles in antitumor immunity. Interleukin-18 (IL-18) can act together with IL-12 in promoting the generation of IFN-gamma producing Th1 cells. The goal of this study was to determine whether cytotoxic T lymphocyte (CTL) secreted in a murine IL-18-induced Th1-dominant state inhibited the development of primary tumors and synchronous liver metastases in orthotopic colon cancer model. EXPERIMENTAL DESIGN: Murine IL-18 gene was transduced into activated T lymphocytes by an adenovirus vector encoding IL-18 (AdIL-18) liposome complex method. Efficacy of adoptive immunogene therapy using AdIL-18 with or without IL-12 was tested in advanced orthotopic xenograft of murine colon cancer. To elucidate the mechanism responsible for the adoptive immunogene therapy, serum IL-4, IL-6, IFN-gamma, and tumor necrosis factor alpha production in Th1/Th2 cytokine balance and quantification of tumor vascularity were investigated. RESULTS: By a modified method of adenoviral gene transduction, T lymphocytes achieved efficient IL-18 production without cell toxicity. Against orthotopic colon cancer, when combined with low dose of recombinant (r) IL-12 (AdIL-18-CTL/rIL-12), the therapeutic efficacy showed much smaller tumors with no liver metastases and no disseminated tumors. There was a significant difference in the volume of primary tumors and the number of liver metastases compared with the group treated with AdIL-18-CTL alone or other group (P < 0.01). In addition, the median survival time of the group treated with AdIL-18-CTL was 53.7 +/- 5.8 days and that of AdIL-18-CTL/rIL-12 was 78.4 +/- 6.1 days, which was also a significant difference (P < 0.01). These antitumor mechanisms were involved with Th1-dominant response in serum Th1/Th2 cytokine balance and suppression of neovascularization at primary tumor site. CONCLUSION: These data suggest that a strategy of Th1/Th2 balance-based adoptive immunogene therapy might be useful for advanced cancer patients.     

Restoration of immunologic responsiveness by PSK in tumor-bearing animals

PSK is a protein-bound polysaccharide prepared from cultured mycelium of the Basidiomycete Coriolus versicolor. Effects of PSK on the immunologic responsiveness in tumor-bearing animals were investigated using syngeneic or allogeneic tumors in mice (Lewis lung carcinoma, B16 melanoma, Meth A fibrosarcoma, adenocarcinoma 755, X5563 plasmacytoma, colon 26, MOPC 31C myeloma, sarcoma 180 and Ehrlich carcinoma), rats (BC47 bladder carcinoma, Walker 256 sarcoma and AH7974 hepatoma), hamsters (HA-1T tumor and RPMI 1846 melanoma), guinea pigs (line-10 hepatoma) and rabbit (VX2 and VX7 tumor). Oral or intraperitoneal administration of PSK restored the depressed delayed hypersensitivity against sheep erythrocytes to a normal level in these tumor-host systems. Also, oral administration of PSK lowered the activity of immunosuppressive substances in the serum of tumor-bearing animals. These results suggest that PSK exhibits antitumor effects by restoring the depressed immunologic responsiveness in tumor-bearing animals.     

Generation of anti-MOPC-315 cytotoxicity in uneducated or in vitro educated spleen cells from normal or MOPC-315 tumor-bearing mice pretreated in vivo with Bacillus Calmette-Guérin

Cultured spleen cells from normal or MOPC-315 tumor-bearing BALB/c mice that were pretreated in vivo with Bacillus Calmette-Guérin (BCG) exhibited in vitro cytotoxicity against MOPC-315 plasmacytoma. In vitro education of BALB/c spleen cells from normal or tumor-bearing mice by cocultivation with mitomycin C-treated MOPC-315 stimulator cells also resulted in antitumor cytotoxicity. The combination of BCG pretreatment of donor mice with the in vitro education of their spleen cells resulted in a level of anti-MOPC-315 cytotoxicity that was greater than the sum of the levels of cytotoxicity exhibited by spleen cells subjected to either process alone. The levels of cytotoxicity exhibited by educated or uneducated spleen cells from BCG-pretreated mice were dependent on the dose of BCG used and on the time interval between in vivo pretreatment and the initiation of in vitro culture. Thus, our findings suggest that educated spleen cells from tumor-bearing hosts that were pretreated with BCG might be useful in immunotherapeutic regimens requiring histocompatible cells with augmented antitumor cytotoxicity.     

Transforming Growth Factor-β CD4+ T cells Tumor-bearing state Immunosuppression Enhanced Production of TGF-β and a Progressive Increase in TGF-β Susceptibility of Anti-tumor CD4+ T Cell Function

The present study deals with the effect of transforming growth factor-β (TGF-β) on anti-tumor immune responsiveness at various stages of the tumor-bearing state. Spleen cells from BALB/c mice bearing a syngeneic tumor (CSA1M) 1–3 wk after inoculation with CSA1M cells produced interleukin-2 (IL-2) and macrophage-activating factor (MAF)/interferon-γ (IFN-γ) upon in vitro culture without addition of exogenous tumor antigens. This lymphokine production was achieved through collaboration between anti-CSA1M CD4⁺ T cells and antigen-presenting cells that had been pulsed with CSA1M tumor antigens in vivo in the tumor-bearing state. The IL-2-producing capacity of CD4⁺ T cells reached the maximal level as early as one week after tumor implantation but decreased with the progress of tumor-bearing stages. In contrast, the capacity of CD4⁺ T cells to produce MAF/IFN-γ was not affected but was maintained at high levels even late in the tumor-bearing state. The addition of recombinant TGF-β (rTGF-β) to cultures of spleen cells from various tumor-bearing stages resulted in the suppression of lymphokine production. However, the magnitude of the TGF-β-induced suppression varied depending on which tumor-bearing stages of splenic cells were tested as a responding cell population; it was slight in cells from early (1–3 wk) tumor-bearing stages but increased in cells from donor mice at later tumor-bearing stages. Thus, spleen cells from late tumor-bearing stages with weak but significant IL-2-producing and considerable MAF/IFN-γ producing capacities failed to produce these lymphokines when rTGF-β was present in cultures. A progressive increase in the TGF-β susceptibility was also observed for IL-4-producing Th2 as well as IL-2/MAF-producing Th1 cells. In addition, increased levels of TGF-β were detected in plasma from tumor-bearing mice at late stages. Taken together, these results indicate that tumor-bearing mice exhibit enhanced production of TGF-β as well as a progressive increase in the susceptibility of anti-tumor CD4⁺ T cells to TGF-β-induced suppressive mechanisms.     

Vaccination with allogeneic GM-CSF gene-modified lung cancer cells: antitumor activity comparing with that induced by autologous vaccine

OBJECTIVE: The aim of this study was to investigate the whole allogeneic (differing tissue-type) tumor cells as vaccine in the mouse lung cancer model. The immunogenic and antitumor activity of allogeneic vaccine was compared with that of autologous cancer cell vaccine. METHODS: C57/BL mice inoculated with Lewis lung cancer (LLC) cells were used as the animal model to test the effects of allogeneic vaccination. LA795 and LLC lung cancer cell lines, which were transfected with the mouse granulocyte-macrophage colony-stimulating factor (GM-CSF) gene, were administered as allogeneic and autologous tumor vaccine, respectively. The irradiated tumor cells were administered as subcutaneous vaccines before the tumor challenge. The immunity of cancer vaccine was tested by mouse interferon-gamma (IFN-gamma) enzyme-linked immunospot (ELISPOT) lactate dehydrogenase (LDH) assays. The serum level of IFN-gamma and interleukin (IL)-4 was tested using the enzyme-linked immunosorbent assay method. RESULTS: Prophylactic vaccination with allogeneic LA795 cells protected against the LLC tumor challenge in C57/BL. The tumor growth was inhibited and the survival was accordingly prolonged. The cytotoxicity of the spleen cells or the purified CD(8)(+) T-cells against LLC cells in the mice immunized with either the autologous or allogeneic cancer cell vaccine was significantly increased, relative to that of the control, untreated group (p<0.05). ELISPOT IFN-gamma assays showed that spleen cells from mice immunized with LA795 cells could be activated after coculture with irradiated LLC cells. In addition, the serum level of Th1-king cytokine IFN-gamma significantly increased after vaccination; however, no statistically difference was found in Th2-kind cytokine IL-4. CONCLUSIONS: The allogeneic cancer vaccine could induce immune responses and protection against lung cancer, which had no significant difference with that of autologous vaccine.     

Effects of interferon-alpha-2a on Th3 cytokine response in multiple myeloma patients

AIMS AND BACKGROUND: Multiple myeloma cells increase Th3 cytokine response by secreting TGF-beta, which causes defective Th1 and Th2 cytokine responses. Therefore, a significant suppression of the immune system is seen in multiple myeloma. Interferon-alpha (IFN-alpha) is used in the treatment of multiple myeloma due to its immunomodulatory and anti-tumoral effects. We attempted to define the characteristics of immune cytokine responses and the effects of IFN-alpha-2a on the immune response in multiple myeloma. METHODS: Fifteen patients with multiple myeloma and 15 healthy controls were enrolled. IFN-alpha-2a, 3 million units/day x 3 times/week, was administered subcutaneously to the patients for 2 weeks. Cytokines (TGF-beta, IL-1, IL-2, IL-4, IL-10, IFN-gamma) were assessed by the ELISA method in sera of the patients in pretreatment and posttreatment periods and in the sera of the controls. RESULTS: IL-2 and IL-4 levels in patients, before IFN-alpha-2a, were lower than the controls, whereas TGF-beta levels were higher than the controls. In other words, Th3 cytokine response was increased and Th1 and Th2 cytokine responses were decreased in patients. A short course of IFN-alpha-2a increased IL-2 levels. CONCLUSIONS: These findings suggest IFN-alpha-2a may enhance nonTh3 cytokine responses in multiple myeloma patients.     

Interleukin-12-induced cytotoxicity against syngeneic B cell lymphomas of SJL/J mice

The B cell lymphomas (RCS) that develop spontaneously in 90% of aging SJL/J mice stimulate syngeneic CD4+ Vbeta16+ Th2 cells to produce cytokines, such as IL-4 and IL-5, which promote lymphoma growth. Although RCS cells express a unique superantigen (vSAg) encoded by an endogenous MMTV (Mtv-29) provirus that also elicits IFN-gamma production from na?ve syngeneic lymphoid cells, there is no development of RCS-specific cytotoxicity. However, addition of IL-12 to co-cultures of SJL spleen and irradiated (gamma-)RCS cells resulted in the appearance of effector cells that killed RCS and NK-susceptible target cells. Antibody depletion studies revealed at least two types of RCS/IL-12-induced cytotoxic cells: (1) NK cells (Asialo GM1+) and (2) CD8+ CTL. Despite high titers of IFN-gamma in the SN of co-culture of SJL spleen and gamma-RCS cells, cytotoxicity only developed if IL-12 was also included in the co-cultures. The results of RNAse protection assays and multi-parameter FACS analysis demonstrated an upregulation of IFN-gamma and decrease in IL-4 by activated Th cells in co-cultures with IL-12. These results indicate that inclusion of IL-12 in primary co-cultures of SJL spleen and gamma-RCS cells influences the qualitative nature of the response to favor use of RCS-responsive Th1 rather than Th2 cells to facilitate the production of cytotoxic effector cells. Results of in vivo experiments support this hypothesis, as judged by tumor growth assays and FACS analysis of the tumor cell content of lymphoid tissues. Inhibition of lymphoma growth was observed in mice given gamma-RCS/IL-12-induced effector cells prior to injection of viable RCS cells. These results demonstrate that IL-12 can be used to alter the host immune response leading to induction of cytotoxic effector cells that inhibit the development and/or progressive growth of otherwise resistant B cell lymphomas in SJL/J mice.     

Successful adoptive immunotherapy with OK432-inducible activated natural killer cells on tumor-bearing mice

We had demonstrated that the NK cell mediated cytotoxicity of murine spleen cells could be augmented by in vivo prime and subsequent in vitro challenge with the streptococcal preparation OK432, and the cell surface phenotype of induced killer cells was Thy 1+, asialo GM1+, suggesting the activated NK cells (OK-NK cell). The culture supernatants of spleen cells with OK432 possessed the activity of IL-2 and IFN-gamma, and the IL-2 played a major role to induce the OK-NK cells via the production of IFN-gamma. In this study, we examined the effect of adoptive transfer of OK-NK cells on tumor-bearing mice. The mice were implanted SP2 myeloma cells intraperitoneally (i.p.), or C26 colon adenocarcinoma cells subcutaneously (s.c.) to make the models of peritonitis carcinomatosa or solid tumor, and the OK-NK cells were transferred i.p. or i.t., adoptively. By the adoptive transfer of OK-NK cells, the 92% of mice bearing SP2-tumor had be cured. The tumor growth of C26-solid tumor was inhibited, and the survival rate of mice bearing C26-tumor was increased, significantly. The intratumoral remnants of 125I-labelled OK-NK cells were 61.27 and 8% after intratumoral transfer, respectively. By multiple transfer of OK-NK cells the anti-tumor effect was more augmented than that of a single transfer. Thus we recognized the anti-tumor effect of adoptive transfer of OK-NK cells on tumor-bearing mice, and suggested that OK-NK cells could be useful for the therapy of cancer patients.     

Effect of PSK on the recovery of macrophage function and T cell-mediated immunity in tumor-bearing mice

The effect of PSK on the depressed bactericidal activity of macrophages and delayed-type hypersensitivity (DTH) to Listeria monocytogenes in BALB/c mice bearing transplantable Meth A fibrosarcoma was studied. In tumor-bearing mice pretreated with PSK, L. monocytogenes was cleared rapidly from the circulating blood and bacterial growth in the liver was inhibited effectively in the early phase of infection. This resistance to the infection could be transferred with peritoneal exudate cells (PEC) but not with non-adherent PE cells of PSK-treated mice. In the early phase of infection, tumor-bearing mice developed a lower level of DTH to L. monocytogenes than did nongrafted control mice. However, the control levels of DTH could be obtained by pretreatment of tumor-bearing mice with PSK. These results suggest that the restoration of resistance to L. monocytogenes in tumor-bearing mice by PSK may be ascribed to both prevention of depression or activation of macrophage function and prevention of depression of T cell-mediated immunity.     

Host response to myeloma: I. Induction of cytotoxic and suppressor T cells by in vivo immunization with MOPC 104E plasmacytoma

Spleen cells from BALB/c mice immunized with mitomycin C-treated MOPC 104E plasmacytoma cells demonstrated negligible cytotoxic activity (less than 10% specific cytotoxic activity) in the 51Cr release assay. These cells exhibited increased cytotoxic activity when they were secondarily sensitized in vitro with mitomycin C-treated MOPC 104E cells. Spleen cells from normal mice showed tumor-specific cytotoxic activity when cocultured with mitomycin C-treated tumor cells at the optimal responder to stimulator ratio of 25:1. The level of cytotoxic activity obtained by in vivo primed and secondarily in vitro sensitized spleen cells did not exceed the level of activity obtained by in vitro primary sensitized cells. Significant suppression of the cytotoxic activity of in vitro primary sensitized cells was observed when cocultured with in vivo primed spleen cells during primary sensitization in vitro at a responder to suppressor cell ratio of 1:1. Suppressor cells of in vivo primed mice were removed by treatment with anti-Thy 1.2 and complement. These results suggest that spleen cells from in vivo primed mice consisted of at least two subpopulations of cells, a cytotoxic (prekiller) and suppressor T cells. Attempts to induce cytotoxic cells in vivo might have failed because of the appearance of suppressor T cells.     

Th17细胞过继免疫治疗对荷弥漫大B细胞淋巴瘤小鼠肿瘤生长的影响

目的 探讨Th17细胞过继免疫治疗对荷弥漫大B细胞淋巴瘤(DLBCL)小鼠肿瘤生长的影响.方法 采用Mini MACS免疫磁珠分离纯化BALB/c小鼠脾来源的CD4+ CD62L+初始T细胞,采用"转化生长因子(TGF-β)、白细胞介素6(IL-6)、干扰素γ抗体(anti-IFN-γ)、白细胞介素4抗体(anti-IL-4)、白细胞介素23(IL-23)"因子组合体外诱导小鼠Th17细胞分化,采用ELISA法测定Th17细胞产生IL-17水平;采用DLBCL细胞株SUDHL-4接种SCID小鼠建立DLBCL荷瘤小鼠模型;选择0、8、18d(3组,5只小鼠/每组)对荷瘤小鼠进行Th17细胞过继免疫治疗,计算肿瘤体积,观察荷瘤小鼠生存期.结果 小鼠在接种SUDHL-4细胞8d左右均形成瘤结节,成瘤率为100％.与对照组小鼠相比,3个过继免疫治疗组小鼠肿瘤体积均明显缩小(P＜0.05),荷瘤小鼠生存期均显著延长(P＜0.05).结论 Th17细胞过继免疫治疗对DLBCL荷瘤小鼠具有抗肿瘤作用.     

In vivo tumor growth enhancement by granulocyte colony-stimulating factor.

The intraperitoneal administration of human recombinant granulocyte colony-stimulating factor (G-CSF) enhanced the growth of intradermally inoculated tumor in mice; in a Meth A fibrosarcoma model, G-CSF administration significantly shortened the latency before tumor appearance, accelerated the increase of tumor size, shortened the survival time of tumor-bearing mice and increased the incidence of lethal tumor growth. A similar growth-enhancing effect of G-CSF was observed in models employing Meth 1 fibrosarcoma, colon carcinoma 26, and L1210 leukemia, although not all the effects were statistically significant. In vitro study showed that G-CSF did not enhance Meth A growth in suspension culture or in soft agar. These data suggest that G-CSF enhances the Meth A growth not directly but through the mediation of host factors. The accumulation of neutrophils was histologically observed in the tumor nodule, the blood, and the spleen in mice given G-CSF repeatedly. The spleen cells and the peripheral blood leukocytes of G-CSF-injected mice enhanced Meth A growth in vitro as compared with those of mice injected with physiological saline. These results suggest the possibility that the in vivo growth of tumor cells was enhanced by G-CSF-induced overproduction of cells including neutrophils.     

Exploitation of interleukin-18 by gastric cancers for their growth and evasion of host immunity

Interleukin-18 (IL-18) is a pleiotropic cytokine that enhances Th1 or Th2 immune response. We show a novel mechanism of gastric cancer cells that allows their immune escape utilizing IL-18. All 4 gastric cancer cell lines, but not colon lines, constitutively expressed IL-18 receptors and IL-18 dose-dependently enhanced their in vitro proliferation accompanied by nuclear factor kappaB activation. When IL-18-pretreated gastric cancer cells were cultured with cytokine-activated peripheral blood killer lymphocytes, the antitumor machineries, perforin or interferon-gamma production of killer lymphocytes decreased, resulting in a decreased susceptibility of cancer cells to killer lymphocytes. Furthermore, gastric cancer cells cultured with IL-18 showed an increased expression of a granzyme B inhibitor, protease inhibitor 9. IL-18 injections into severe combined immuno-deficient mice intraperitoneally inoculated with gastric cancer cells consistently decreased the mouse survival time. Our results indicate that gastric cancers exploit IL-18 to grow/invade and evade immunosurveillance in the hosts.     

In vivo Tumor Growth Enhancement by Granulocyte Colony-stimulating Factor

The intraperitoneal administration of human recombinant granulocyte colony-stimulating factor (G-CSF) enhanced the growth of intradermally inoculated tumor in mice; in a Meth A fibrosarcoma model, G-CSF administration significantly shortened the latency before tumor appearance, accelerated the increase of tumor size, shortened the survival time of tumor-bearing mice and increased the incidence of lethal tumor growth. A similar growth-enhancing effect of G-CSF was observed in models employing Meth 1 fibrosarcoma, colon carcinoma 26, and L1210 leukemia, although not all the effects were statistically significant. In vitro study showed that G-CSF did not enhance Meth A growth in suspension culture or in soft agar. These data suggest that G-CSF enhances the Meth A growth not directly but through the mediation of host factors. The accumulation of neutrophils was histologically observed in the tumor nodule, the blood, and the spleen in mice given G-CSF repeatedly. The spleen cells and the peripheral blood leukocytes of G-CSF-injected mice enhanced Meth A growth in vitro as compared with those of mice injected with physiological saline. These results suggest the possibility that the in vivo growth of tumor cells was enhanced by G-CSF-induced overproduction of cells including neutrophils.     

ONO-4007, a synthetic lipid A analog,induces Th1-type immune response in tumor eradication and restores nitric oxide production by peritoneal macrophages

We have reported that ONO-4007, a novel synthetic lipid A derivative with low toxic activities, produced large amount of tumor necrosis factor (TNF)-alpha selectively in the tumor tissues and brought about complete cures in about 60% of rats bearing TNF-alpha sensitive KDH-8 cells, which also secreted a large amount of transforming growth factor (TGF)-beta. In our present study, to explore ONO-4007 induced Th1-type immune response, we investigated the mRNA expression of interferon (IFN)-gamma, Interleukin (IL)-1beta, IL-6, IL-10, IL-12 in KDH-8 bearing rats. We next examined the nitric oxide (NO) production. We found that IFN-gamma, IL-1beta, IL-6 and IL-12 mRNA expression of the tumor tissue were higher in the ONO-4007 treated rats than in phosphate buffer saline (PBS) treated rats. Western blotting also revealed that IL-12 protein production was increased. NO production from peritoneal macrophages were suppressed in tumor-bearing rats, but ONO-4007 restored it up to the normal level. These results suggest that ONO-4007 induces and restores Th1-type immune response through cytokine production cascade, followed by initial TNF-alpha production, eventually leading to tumor eradication.     

GM-CSF基因修饰肺癌细胞疫苗的抗肿瘤活性及其与化疗的协同作用

目的评价粒细胞-巨噬细胞集落刺激因子(GM-CSF)基因修饰肿瘤疫苗的抗肿瘤活性,探讨其与化疗联合应用的抗肿瘤效果。方法以小鼠肺癌Lewis细胞系接种C57BL/6小鼠建立动物模型。利用含GM-CSF基因的重组质粒GM-CSF-pIRES2-EGFP,转染小鼠肺癌细胞系Lewis和LA795细胞,分别制备自体(Lewis细胞)和同种异体(LA795细胞)肿瘤疫苗。小鼠皮下接种Lewis细胞(1×107个)后5 d,采用GM-CSF分泌性肿瘤疫苗接种3次,同时设PBS组和单纯疫苗组作为对照,检测疫苗治疗前后脾细胞对Lewis细胞杀伤活性的变化,以及血清白介素4(IL-4)和γ干扰素(IFN-γ)的水平。观察GM-CSF分泌性肿瘤疫苗接种及联合化疗对小鼠生存期的影响。结果GM- CSF分泌性自体或同种异体肿瘤疫苗,均可诱导小鼠脾细胞对Lewis细胞杀伤活性增高,第3次接种后分别为(42.0±2.5)%和(39.6±7.3)%;同时血清中Th1类细胞因子IFN-γ的水平升高,而Th2类因子IL-4的水平无显著变化。GM-CSF分泌性肿瘤疫苗治疗组小鼠生存期与对照组比较,差异无统计学意义(P>0.05);而化疗联合疫苗组小鼠生存期较单独治疗组及对照组明显延长(P<0.05)。结论GM-CSF基因修饰的肿瘤疫苗可刺激机体产生特异性免疫反应;化疗的联合应用有助于提高肿瘤疫苗的治疗效果。     

Critical role of the Th1/Tc1 circuit for the generation of tumor-specific CTL during tumor eradication in vivo by Th1-cell therapy

Th1 and Th2 cells obtained from OVA-specific T cell receptor transgenic mice completely eradicated the tumor mass when transferred into mice bearing A20-OVA tumor cells expressing OVA as a model tumor antigen. To elucidate the role of Tc1 or Tc2 cells during tumor eradication by Th1- or Th2-cell therapy, spleen cells obtained from mice cured of tumor by the therapy were restimulated with the model tumor antigen (OVA) for 4 days. Spleen cells obtained from mice cured by Th1-cell therapy produced high levels of IFN-γ, while spleen cells from mice cured by Th2-cell therapy produced high levels of IL-4. Intracellular staining analysis demonstrated that a high frequency of IFN-γ-producing Tc1 cells was induced in mice given Th1-cell therapy. In contrast, IL-4-producing Tc2 cells were mainly induced in mice after Th2-cell therapy. Moreover, Tc1, but not Tc2, exhibited a tumor-specific cytotoxicity against A20-OVA but not against CMS-7 fibrosarcoma. Thus, immunological memory essential for CTL generation was induced by the Th1/Tc1 circuit, but not by the Th2/Tc2 circuit. We also demonstrated that Th1-cell therapy is greatly augmented by combination therapy with cyclophosphamide treatment. This finding indicated that adoptive chemoimmuno-therapy using Th1 cells should be applicable as a novel tool to enhance the Th1/Tc1 circuit, which is beneficial for inducing tumor eradication in vivo.