Murine B16 melanoma vaccination-induced tumor immunity: identification of specific immune cells and functions involved.

Vaccination using inactivated B16 melanoma cells that have been treated in vitro for > 2 weeks with interferon-alpha (IFN-alpha) (B16alpha cells) has been shown to elicit a protective host antitumor immunity. In these studies, vaccination with B16alpha cells has been shown to provide protection against primary B16 tumor challenge, established B16 tumors, and metastatic B16 tumors. Specific immune cells and factors that might mediate this tumor immunity have now been evaluated. Macrophage depletion studies suggest that macrophage function is required for expression of tumor immunity either for processing of antigen or for cytokine production but that macrophage function is not involved in direct cytotoxicity against the B16 challenge tumor. CD8(+) T cell depletion studies show that cytotoxic T cell function is required for expression of tumor immunity. Syngeneic knockout mouse experiments offer further insights into the immune cells and factors that mediate the development and expression of tumor immunity. First, interleukin-12 (IL-12) knockout mouse experiments identify IL-12 as an important cytokine in mediating the development of tumor immunity. Second, specific knockout mouse experiments show that tumor immunity requires the function of CD4(+) T cells, CD8(+) T cells, and natural killer (NK) cells. Third, specific knockout mouse experiments show that tumor immunity does not require the function of B cells. The results suggest that vaccination with inactivated B16alpha cells induces an active, cell-mediated immunity to B16 melanoma cells. The tumor vaccination protocol with B16alpha cell vaccinations establishes a potent tumor immunity against B16 melanoma tumors in mice and may serve as a model for induction of tumor immunity against primary or secondary melanoma tumors in humans.     

NK cells and NKT cells collaborate in host protection from methylcholanthrene-induced fibrosarcoma

NK1.1(+) V(alpha)14J(alpha)281(+) (NKT) cells can be induced by IL-12 therapy to mediate tumor rejection; however, methylcholanthrene (MCA)-induced fibrosarcoma is the only tumor model described where NKT cells play a natural role in controlling tumor initiation. From our previous study in C57BL/6 mice it remained unclear whether NK cells were also involved in this natural response. Herein, to discriminate the function of NK and NKT cells, we have evaluated fibrosarcoma development in mice deficient in NKT cells, but not NK cells, and mice deficient in NK cells, but not NKT cells. The results indicate that both NK cells and NKT cells are essential and collaborate in natural host immunity against MCA-induced sarcoma. In contrast, sarcoma incidence and growth rate were reduced using IL-12 therapy, this effect was mediated in the absence of T cells (including NKT cells), but not NK cells.     

Specificity of the T cells that mediate and suppress adoptive immunotherapy of established tumors

This study was designed to investigate the specificity of the T cells that express and suppress antitumor immunity in a model of adoptive immunization against established tumors. Results obtained with the P815 mastocytoma, L5178Y lymphoma, and P388 lymphoma showed, in agreement with previous findings from this laboratory, that an intravenous infusion of splenic T cells from immunized mice can cause the regression of a tumor growing in T-cell-deficient mice. So far as specificity of adoptive immunity is concerned, reciprocal passive transfer experiments with these three tumors revealed that T cells from donor mice immunized against the P815 tumor are not capable of causing regression of the P388 tumor or L5178Y tumor, even if both the P815 and L5178Y tumors are growing in the same host. Similarly splenic T cells from mice immunized against the P388 tumor or L5178Y tumor had no effect on growth of the P815 tumor. Suppression of adoptive immunity was also specific, in that passively transferred suppressor T cells from mice bearing a progressive P815 tumor were capable of suppressing adoptive T-cell-mediated regression of the P815 tumor, but not the P388 tumor growing in T-cell-deficient recipients. Reciprocally, P388 suppressor spleen cells from mice bearing a progressive P388 tumor prevented adoptive T-cell-mediated regression of the P388 tumor, but not the P815 tumor. The results indicate, therefore, that the T cells from immunized mice that mediate adoptive antitumor immunity and the T cells from tumor-bearing mice that suppress the expression of this immunity are specific for the tumor that evokes their generation.     

CD169-positive macrophages dominate antitumor immunity by crosspresenting dead cell-associated antigens

The generation of tumor-directed cytotoxic T lymphocytes is considered crucial for the induction of antitumor immunity. To activate these CD8(+) T?cells, antigen-presenting cells (APCs) must initially acquire tumor cell-associated antigens. The major source of tumor antigens is dead tumor cells, but little is known about how APCs in draining lymph nodes acquire and crosspresent these antigens. Here we show that CD169(+) macrophages phagocytose dead tumor cells transported via lymphatic flow and subsequently crosspresent tumor antigens to CD8(+) T?cells. Subcutaneous immunization with irradiated tumor cells protects mice from syngenic tumor. However, tumor antigen-specific CD8(+) T?cell activation and subsequent antitumor immunity are severely impaired in mice depleted with CD169(+) macrophages. Neither migratory dendritic cells (DCs) nor lymph node-resident conventional DCs are essential for the crosspresentation of tumor antigens. Thus, we have identified CD169(+) macrophages as lymph node-resident APCs dominating early activation of tumor antigen-specific CD8(+) T?cells.     

Effective induction of therapeutic antitumor immunity by dendritic cells coexpressing interleukin-18 and tumor antigen

Dendritic cell (DC) based cancer vaccine can induce potent antitumor immunity in murine models; however, objective clinical responses have been observed only in a minority of cancer patients. To improve the antitumor effect of DC vaccine, Th1-biasing cytokine interleukin (IL) 18 and melanoma-associated antigen gp100 were cotransfected into bone marrow-derived DC (IL-18/gp100-DC), which were used as vaccine to induce the protective and therapeutic immunity in a B16 melanoma model. Immunization with IL-18/gp100-DC resulted in tumor resistance in 87.5% of the mice challenged with B16 cells; however, 12.5% and 25% of mice immunized with gp100 gene-modified DC (gp100-DC) or IL-18 gene-modified DC (IL-18-DC) were tumor free, respectively. Most importantly, IL-18/gp100-DC immunization led to the generation of potent therapeutic immunity that significantly inhibited the tumor growth and improved the survival period of mice bearing established melanoma. Immune cell depletion experiments identified that CD4(+) T cells also played an important role in the priming phase of antitumor immunity and CD8(+) T lymphocytes were the primary effectors. gp100-specific CTL response were induced most markedly in the tumor-bearing mice immunized with IL-18/gp100-DC. Administration with such vaccine also significantly increased the production of Th1 cytokine (IL-2 and interferon-gamma) and induced infiltration of inflammatory cells inside and around the tumors. In addition, natural killer cell activity was also augmented. These results indicate that immunization with DC vaccine coexpressing Th1 cytokine IL-18 and tumor antigen gene may be an effective strategy for a successful therapeutic vaccination.     

IFN-alpha-induced murine B16 melanoma cancer vaccine cells: induction and accumulation of cell-associated IL-15.

Long-term treatment of mouse cancer cells with interferon-alpha (IFN-alpha) converts parental B16 melanoma cells to B16alpha vaccine cells. Inoculation of syngeneic mice with B16alpha vaccine cells triggers immunity to the parental B16 tumor that is mediated by host macrophages, T cells, and natural killer (NK) cells. Lymph node cells from mice inoculated with irradiated B16alpha vaccine cells, but not with irradiated parental cells, proliferate when cultured in vitro, suggesting long-term in vivo activation of lymphoid cells. Long-term IFN-alpha treatment of B16alpha vaccine cells induced both interleukin-15 (IL-15) mRNA and IL-15 protein. The bulk of the induced IL-15 remained cell associated, either cytoplasmic or associated with the cell membrane. Immunofluorescence microscopy studies showed that the cell-associated IL-15 was broadly distributed throughout the cytoplasm. These observations suggest that long-term IFN-alpha treatment may induce primarily the truncated isoform of IL-15. Vaccination with irradiated B16alpha vaccine cells may promote tumor immunity by releasing high levels of cell-associated IL-15 when spontaneously lysed or directly killed by innate immune cells. The release of accumulated cell-associated IL-15 may then trigger a host T cell response to tumor antigens and cause host development of immunity to the B16 tumor cells.     

CD4+ T helper cell-independent antitumor response mediated by murine IFN-beta gene delivery in immunocompetent mice.

Previously, we provided evidence that adenovirus-mediated interferon-beta (IFN-beta) gene therapy inhibits tumor formation and causes dramatic regression of established tumors in immunodeficient mice. We suggested that local IFN-beta gene therapy with adenoviral vectors could be an effective treatment for cancer. In this report, the actions of murine IFN-beta (MuIFN-beta) gene delivery on both subcutaneous and metastatic tumors were evaluated in syngeneic immunocompetent mice. We found that the antitumor response mediated by MuIFN-beta gene delivery relied on CD8(+) T cells but was completely independent of CD4(+) T cells. In fact, depletion of CD4(+) T cells appeared to enhance the effect on tumor inhibition and animal survival induced by adenovirus-MuIFN-beta gene delivery. Therefore, adenovirus-MuIFN-beta gene therapy can bypass CD4(+) T helper (Th) cells and activate an effective CD8(+) T cell-dependent antitumor immunity in immunocompetent mice. Furthermore, we found that depletion of macrophages but not natural killer (NK) cells suppressed the antitumor response induced by MuIFN-beta gene therapy. These data, together with our previous results, suggest that in the clinical setting, local adenovirus-mediated IFN-beta gene therapy may lead to an efficient and long-lasting eradication of tumors by a direct antitumor effect and via activation of the innate and the adoptive immune systems.     

Cytokine gene therapy of mesothelioma. Immune and antitumor effects of transfected interleukin-12.

Malignant mesothelioma (MM) is a solid tumor of the mesothelium for which there is no curative treatment. MM appears to be sensitive to immunotherapeutic approaches, and one of the most powerful immunomodulatory cytokines with antitumor effects is interleukin (IL)-12. We have previously shown in a murine model of MM that systemic administration of recombinant IL-12 induces a potent anti-MM immune response. The nature and accessibility of MM tumors means that they are suitable candidates for direct cytokine and gene-transfer therapeutic approaches. Therefore, we undertook a study to assess the antitumor effects induced by the local production of IL-12 within MM tumors by transfecting a murine MM line with the genes for IL-12. The IL-12 transfectant (AB1-IL-12) did not produce tumors in normal mice, but did so in athymic nude mice, implicating T cells in the prevention of MM tumor growth. In mixing experiments, paracrine IL-12 production inhibited growth of untransfected MM cells provided that cells producing IL-12 represented more than 50-80% of the inoculum. Furthermore, BALB/c mice previously challenged with AB1-IL-12 were protected against rechallenge with parental AB1 tumor, indicating that the transfectant induced long-term immunity. AB1-IL-12 induced systemic immunity that was effective at reducing the incidence of parental AB1 tumor at a distal site, but its effects were dose-dependent. Though both CD4(+) and CD8(+) cells infiltrated the rejecting tumor, CD8(+) effector cells were essential for protection against development of parental AB1 tumor. This study shows that paracrine secretion of IL-12, generated by gene transfer, can induce immunity against MM that can act locally and also at a distant site. In addition, there was no evidence of toxicity, which has been associated with the systemic administration of IL-12, indicating that this cytokine is a good candidate for experimental gene therapy in MM.     

束缚应激对S180荷瘤小鼠Th1/Th2型细胞因子及肿瘤生长的影响

目的:观察束缚应激对荷S180瘤小鼠Th1/Th2型细胞因子及肿瘤生长的影响。方法:取腹腔传代第7天的肿瘤细胞S180,调细 胞密度至1×1010/L,注射于昆明小鼠右腋皮下,每只0.2 mL。接种后束缚限制活动,8 h/d,并设单纯束缚组、单纯肿瘤组和正常对照组。10 d后处死小鼠,剥取肿瘤称瘤重,计算胸腺指数,分别采用MTT比色法和丝裂原激活淋巴母细胞法检测脾T细胞增殖及产生Th1型细胞因子IL-2、IFN-γ的能力,并取血清用ELISA法检测Th2型细胞因子IL-4、IL-10的含量。结果:束缚应激可明显增加荷瘤小鼠的瘤重(P<0.01),降低小鼠胸腺指数和脾T细胞的增殖能力(P值分别<0.01),降低荷瘤小鼠脾细胞产生IL-2和IFN-γ的能力(P值分别<0.01),并可使小鼠血清IL-4、IL-10的含量明显增加(P值分别<0.01和<0.05)。结论:束缚应激可显著抑制荷瘤小鼠的细胞免疫功能,使产生Th1型细胞因子的功能减弱,Th2型细胞因子的含量增加,导致Th1/Th2细胞的平衡进一步向Th2细胞漂移。这可能是其促进肿瘤生长的重要机制。     

Induction of immunity to neuroblastoma early after syngeneic hematopoietic stem cell transplantation using a novel mouse tumor vaccine.

Autologous HSCT has resulted in improved event-free survival in patients with advanced neuroblastoma, but most of these patients still relapse. We previously reported that transient transfection of mouse neuroblastoma cells with plasmid DNA vectors encoding immune costimulatory molecules generates cell-based vaccines capable of inducing potent antitumor T cell immunity. In this study, we explored the effectiveness of tumor vaccine administration soon after HSCT. Soon after transplantation, only vaccinated mice that had received an adoptive transfer of syngeneic T cells survived tumor challenge. Tumor protective immunity in the transplant recipients was dependent on CD4(+) and CD8(+) T cells, and tumor-reactive T cells in the spleens of vaccinated mice could be detected in IFN-gamma enzyme-linked immunosorbent spot (ELISPOT) assays. Our data indicate that the adoptive transfer of T cells was absolutely required for induction of protective immunity by the tumor vaccine. Adoptive transfer of T cells accelerated T cell reconstitution, but it also resulted in increased percentages of CD4(+)CD25(+)Foxp3(+) cells soon after HSCT. Treatment of HSC transplant recipients with an anti-CD25 mAb before tumor vaccination inhibited antitumor immunity and significantly decreased the number of IFN-gamma-secreting tumor-specific CD4 T cells. However, physical depletion of CD25(+) cells from the adoptively transferred splenocytes appeared to increase the efficacy of tumor vaccination. Collectively, these results demonstrate that anti-neuroblastoma immunity can be induced soon after HSCT using a novel cell-based cancer vaccine. However, sufficient numbers of T cells must be added to the graft to achieve protective antitumor immunity, and depletion of CD25(+) T cells from adoptively transferred T cells might provide some additional benefit. These translational studies will aid in our development of post-HSCT vaccines for neuroblastoma.     

白细胞介素23在小鼠乳腺癌中的抗肿瘤作用及其免疫机制

目的: 研究白细胞介素23(IL-23)在小鼠乳腺癌中的抗肿瘤作用及其免疫功能变化.方法: 将逆转录病毒介导转染IL-23基因的小鼠乳腺癌细胞(IL-23/MA-891)、转染逆转录病毒空载体的小鼠乳腺癌细胞(LXSN/ MA-891)及亲代小鼠乳腺癌细胞(MA-891)分别接种于小鼠皮下, 观察小鼠成瘤及肿瘤生长情况; 30 d时取3组小鼠脾脏和肿瘤组织, 用ELISA法检测3组小鼠脾细胞在MA-891诱导下IFN-?、 TNF-á、 IL-12和IL-4的产生情况; 用流式细胞术(FCM)检测肿瘤组织细胞表面分子MHC-Ⅰ、 MHC-Ⅱ、 CD80、 CD86的表达, 检测脾细胞中CD11c阳性细胞的比率, 并对脾细胞中CD4 、 CD8 淋巴细胞进行分选; 用免疫组织化学技术对3组肿瘤组织中CD4 、 CD8 淋巴细胞浸润情况进行检测.结果: IL-23基因转染组小鼠皮下结节生长速度明显慢于接种空载体转染组及未转染组; 接种IL-23/MA-891细胞的小鼠脾细胞可产生较水平的IFN-γ、 TNF-á和IL-12等Th1类及相关细胞因子, 与接种LXSN/MA-891细胞和MA-891细胞2组小鼠的脾细胞相比明显增高(P<0.01), 而Th2类细胞因子IL-4的水平却无统计学意义(P>0.05); 接种IL-23/MA-891细胞组小鼠脾细胞中CD11c阳性细胞率、 CD4 、 CD8 淋巴细胞比率以及肿瘤组织中CD4 、 CD8 淋巴细胞浸润程度均较LXSN/MA-891、 MA-891组明显增加(P<0.01); IL-23/MA-891细胞组小鼠肿瘤组织细胞表面MHC-Ⅰ、 MHC-Ⅱ、 CD80、 CD86分子的表达明显提高(P<0.01).结论: 转染IL-23基因的小鼠乳腺癌细胞所分泌的IL-23具有生物学活性, 增强了细胞免疫功能, 在小鼠体内发挥了明显的抗肿瘤作用.     

Effects of IL-1 molecules on growth patterns of 3-MCA-induced cell lines: An interplay between immunogenicity and invasive potential

The balance between inflammation and immunity is cardinal for the outcome of the malignant process. Local attenuated inflammatory responses mediated by innate cells may provide accessory signals for the development of acquired immunity against malignant cells. In contrast, excessive inflammatory responses accompany tumorigenesis and tumor invasiveness, by the induction of immunosuppression. In the present study, we have assessed the role of tumor cell-derived IL-1 in determining the invasive versus immunostimulatory potential of tumor cells. For this purpose, we have used 3-MCA-induced fibrosarcoma cell lines from IL-1 knockout (KO) versus control mice. Cell lines with no IL-1 failed to establish tumors in intact mice, while lines obtained from control mice were invasive and induced a potent angiogenic response. In contrast, cell lines from IL-1KO mice were more immunogenic. SDF-1 and IL-6, each induced by IL-1, were the two major cytokines whose levels differed in cell lines with or without IL-1. We could not detect differences in cell surface markers related to immunogenicity, such as MHC Class I, co-stimulatory, or adhesion molecules between both types of cells. However, more T-cells were observed at the inoculation site of tumor cells devoid of IL-1 and more pronounced parameters related to anti-tumor immunity were observed in the spleen (IL-12 and IFNγ) of these mice, compared to mice bearing tumors derived from control mice, where host-derived IL-1 is present. In addition, injection of tumor cells devoid of IL-1, which failed to grow in mice, induced an anti-tumor cell immune memory, while in mice injected with tumor cells from control mice; no immune memory could be detected. From the results, it seems that IL-1 is a crucial factor in determining the balance between immunity and inflammation in tumor-bearing mice. This suggests that manipulation of IL-1 could be useful in anti-tumor therapy, by reducing invasiveness and promoting immunity against the malignant cells.     

Effect of subhypnotic doses of dexmedetomidine on antitumor immunity in mice

Dexmedetomidine, a selective alpha2 adrenergic receptor agonist, is a drug often used for sedation. Despite the high prevalence of sedating patients with tumors in intensive care settings, little is known about the effect of sedative drugs on tumor growth. We studied the effect of dexmedetomidine on antitumor immunity in mice. Subhypnotic doses of dexmedetomidine decreased interleukin (IL)-12 production from thioglycollate-induced macrophages. The treatment also decreased the ratio of the helper T lymphocytes subsets, Th1 to Th2 (Th1/Th2), in the spleen. Following subcutaneous inoculation of EL4 T-cell lymphoma cells, dexmedetomidine further decreased the splenic Th1/Th2 ratio and activity of EL4-specific cytotoxic T lymphocytes (CTLs). Finally, treatment with dexmedetomidine accelerated EL4 growth in mice. These data show that treatment of mice with subhypnotic doses of dexmedetomidine down-regulates antitumor immunity, possibly through the decreased production of IL-12 from antigen presenting cells, resulting in a Th2 shift and decreased CTL activity against EL4 in mice.     

Inhibition of tumor-associated macrophages by trabectedin improves the antitumor adaptive immunity in response to anti-PD-1 therapy

A considerable proportion of cancer patients are resistant or only partially responsive to immune checkpoint blockade immunotherapy. Tumor-Associated Macrophages (TAMs) infiltrating the tumor stroma suppress the adaptive immune responses and, hence, promote tumor immune evasion. Depletion of TAMs or modulation of their protumoral functions is actively pursued, with the purpose of relieving this state of immunesuppression. We previously reported that trabectedin, a registered antitumor compound, selectively reduces monocytes and TAMs in treated tumors. However, its putative effects on the adaptive immunity are still unclear. In this study, we investigated whether treatment of tumor-bearing mice with trabectedin modulates the presence and functional activity of T-lymphocytes. In treated tumors, there was a significant upregulation of T cell-associated genes, including CD3, CD8, perforin, granzyme B, and IFN-responsive genes (MX1, CXCL10, and PD-1), indicating that T lymphocytes were activated after treatment. Notably, the mRNA levels of the Pdcd1 gene, coding for PD-1, were strongly increased. Using a fibrosarcoma model poorly responsive to PD-1-immunotherapy, treatment with trabectedin prior to anti-PD-1 resulted in improved antitumor efficacy. In conclusion, pretreatment with trabectedin enhances the therapeutic response to checkpoint inhibitor-based immunotherapy. These findings provide a good rational for the combination of trabectedin with immunotherapy regimens.     

Antibody treatment of human tumor xenografts elicits active anti-tumor immunity in nude mice

Athymic nude mice bearing subcutaneous tumor xenografts of the human anti-colorectal cancer cell line SW480 were used as a preclinical model to explore anti-tumor immunotherapies. Intratumor or systemic treatment of the mice with murine anti-SW480 serum, recombinant anti-SW480 polyclonal antibodies, or the anti-colorectal cancer monoclonal antibody CO17-1A, caused retardation or regression of SW480 tumor xenografts. Interestingly, when mice that had regressed their tumors were re-challenged with SW480 cells, these mice regressed the new tumors without further antibody treatment. Adoptive transfer of spleen cells from mice that had regressed their tumors conferred anti-tumor immunity to na?ve nude mice. Pilot experiments suggest that the transferred anti-tumor immunity is mediated by T cells of both gammadelta and alphabeta lineages. These results demonstrate that passive anti-tumor immunotherapy can elicit active immunity and support a role for extra-thymic gammadelta and alphabeta T cells in tumor rejection. Implications for potential immunotherapies include injection of tumor nodules in cancer patients with anti-tumor antibodies to induce anti-tumor T cell immunity.     

The role of T helper 17 and regulatory T cells in tumor microenvironment

T helper 17 (Th17) cells were first described as a novel T helper cell lineage independent from Th1 and Th2 subsets. Th17 cells play vital roles in inflammation and tumor immunity. It causes the dissipation of antitumor immunity and contribution to the survival of tumor cells, worsening tumor growth and metastasis. Tumor-infiltrating Th17 cells were seen innumerous cancers in mice and humans. There has been an association between intratumoral Th17 cell infiltration and both good and bad prognoses. Besides the protumoral roles defined for IL-17 andTh17 cells, several reports have shown that Th17 cells also drive antitumoral immunity. Various mechanisms by which Th17 cells control tumor growth are as following: recruitment of several immune cells including DCs, CD4⁺ T cells, and CD8⁺ T cells within tumors, activation of CD8⁺ T cells, and probably plasticity toward Th1 phenotype, related to IFN-γ and TNF-α production. Regulatory T cells (Tregs) have been exhibited to infiltrate human tumors and are believed to restrict antitumor immunity. The effect of Treg cells has been more controversial. Whereas some studies have proposed that a high density of Treg cells within the tumor associated with a poor clinical prognosis, other studies have presented a positive clinical prognosis, underlining the importance of elucidating the clinical significance of Treg cells further. Treg and Th17 cells play both positive and negative roles in regulating antitumor immune responses. In spite of the presence of these cells, yet some tumors develop and grow. These T cells by themselves are not adequate to efficiently mount antitumor immune responses.     

CD8alpha+ dendritic cells enhance the antigen-specific CD4+ T-cell response and accelerate development of collagen-induced arthritis

To investigate the role of CD8alpha(+) DCs in the development of collagen-induced arthritis (CIA). The immunogenic properties of CD8alpha(+) and CD8alpha(-) DC subsets were investigated by mixed-lymphocyte reaction and cytokine enzyme-linked immunoassay. CII-pulsed CD8alpha(+) DCs or CD8alpha(-) DCs with CD4(+) T cells from CIA mice were adoptively transferred onto the hind footpad of DBA mice. The onset of arthritis and the arthritis index were examined for 14 weeks after adoptive transfer. Expression of MHC-II and CD80 but not CD86 and CD40 was higher in CD8alpha(+) DCs than in CD8alpha(-) DCs from the spleens of CIA mice. Culturing CD8alpha(+) DCs with CD4(+) T cells significantly increased the proliferative response of CD4(+) T cells in the presence of CII. The production of interleukin (IL)-12p70, IL-17, interferon (IFN)-gamma, and tumor necrosis factor (TNF)-alpha was slightly increased in CD8alpha(+) DCs than in CD8alpha(-) DCs. DBA/1 mice that were adoptively transferred with CII-pulsed CD8alpha(+) DCs and CD4(+) T cells into the footpads showed accelerated onset of CIA compared to control group. By contrast, CD8alpha(-) DCs showed a partial inhibitory effect on CIA. These findings show that CD8alpha(+) DCs accelerated the onset of CIA when aoptively transferred with CD4(+) T cells and that CD8alpha(+) DCs provoke the development of CIA probably by stimulating the immune responses of CII-reactive CD4(+) T cells and by increasing the production of inflammatory cytokines.     

The inducible costimulator (ICOS) is critical for the development of human T(H)17 cells

Human T helper 17 (T(H)17) cells regulate host defense, autoimmunity, and tumor immunity. Although cytokines that control human T(H)17 cell development have been identified, the costimulatory molecules important for T(H)17 cell generation are unknown. Here, we found that the inducible costimulator (ICOS) was critical for the differentiation and expansion of human T(H)17 cells. Human cord blood contained a subset of CD161(+)CD4(+) T cells that were recent emigrants from the thymus, expressed ICOS constitutively, and were imprinted as T(H)17 cells through ICOS signaling. ICOS stimulation induced c-MAF, RORC2, and T-bet expression in these cells, leading to increased secretion of interleukin-21 (IL-21), IL-17, and interferon-γ (IFN-γ) compared with cells stimulated with CD28. Conversely, CD28 ligation abrogated ICOS costimulation, dampening RORC2 expression while promoting the expression of the aryl hydrocarbon receptor, which led to reduced secretion of IL-17 and enhanced production of IL-22 compared with cells stimulated with ICOS. Moreover, ICOS promoted the robust expansion of IL-17(+)IFN-γ(+) human T cells, and the antitumor activity of these cells after adoptive transfer into mice bearing large human tumors was superior to that of cells expanded with CD28. The therapeutic effectiveness of ICOS-expanded cells was associated with enhanced functionality and engraftment in vivo. These findings reveal a vital role for ICOS signaling in the generation and maintenance of human T(H)17 cells and suggest that components of this pathway could be therapeutically targeted to treat cancer or chronic infection and, conversely, that interruption of this pathway may have utility in multiple sclerosis and other autoimmune syndromes. These findings have provided the rationale for designing new clinical trials for tumor immunotherapy.