A GM-CSF/CD40L producing cell augments anti-tumor T cell responses

BACKGROUND: Tumors evade T cell-mediated rejection despite the presence of tumor associated antigens (TAAs) and T cells specific for these TAAs in cancer patients. Therapeutic tumor vaccines are being developed to prevent this evasion. Previous reports revealed that anti-tumor T cell responses could be activated in mice when granulocyte macrophage-colony stimulating factor (GM-CSF) or CD40L are produced at tumor vaccine sites. We sought to test the hypothesis that production of GM-CSF and CD40L by a bystander cell line could induce an anti-tumor T cell response in an in vitro human model. MATERIALS AND METHODS: The K562 cell line was stably transfected with the human GM-CSF and CD40L genes. The effect of this cell line on T cell responses was tested in a human autologous mixed tumor cell/lymph node cell model using tissue from a series of cancer patients. RESULTS: There was no significant anti-tumor T cell response when human lymphocytes derived from tumor-draining lymph nodes were stimulated with autologous tumor cells in vitro. However, significant anti-tumor T cell responses were observed when bystander cells transfected with CD40L and GM-CSF were added to the cultures. CONCLUSIONS: A fully autologous human model consisting of tumor cells as stimulator cells and tumor-draining lymph nodes as responder cells can be used to test immunotherapeutic strategies. T cells in these lymph nodes are unresponsive to autologous tumor cells, but this lack of responsiveness can be reversed in the presence of GM-CSF and CD40L. These data provide a rationale for testing tumor cell vaccines incorporating GM-CSF- and CD40L-expressing bystanders in clinical trials.     

Induction of antiviral cytotoxic T cells by plasmacytoid dendritic cells for adoptive immunotherapy of posttransplant diseases

Virus-associated hematologic malignancies (EBV lymphoproliferative disease) and opportunistic infections (CMV) represent a major cause of hematopoietic stem cell and solid organ transplantation failure. Adoptive transfer of antigen-specific T lymphocytes appears to be a major and successful immunotherapeutic strategy, but improvements are needed to reliably produce high numbers of virus-specific T cells with appropriate requirements for adoptive immunotherapy that would allow extensive clinical use. Since plasmacytoid dendritic cells (pDCs) are crucial in launching antiviral responses, we investigated their capacity to elicit functional antiviral T-cell responses for adoptive cellular immunotherapy using a unique pDC line and antigens derived from Influenza, CMV and EBV viruses. Stimulation of peripheral blood mononuclear cells from HLA-A*0201(+) donors by HLA-A0201 matched pDCs pulsed with viral-derived peptides triggered high levels of multi-specific and functional cytotoxic T-cell responses (up to 99% tetramer(+) CD8 T cells) in vitro. Furthermore, the central/effector memory cytotoxic T cells elicited by the pDCs strongly display antiviral activity upon adoptive transfer into a humanized mouse model that mimics a virus-induced malignancy. We provide a simple and potent method to generate virus-specific CTL with the required properties for adoptive cellular immunotherapy of post-transplant diseases.     

Generation of helper and cytotoxic CD4+T cell clones specific for the minor histocompatibility antigen H-Y, after in vitro priming of human T cells by HLA-identical monocyte-derived dendritic cells

BACKGROUND: There is now convincing evidence that minor histocompatibility antigens (mHag) may play a significant role in the pathogenesis of graft-versus-host disease after HLA-identical bone marrow transplantation. Indeed, in this clinical situation, T cells specific for mHag have been isolated. Here, we addressed whether one can generate mHag-specific T cells in vitro, without any in vivo immunization, among healthy blood donors. METHODS: We used monocyte-derived dendritic cells (Mo-DCs) as antigen presenting cells to induce primary responses between healthy HLA-identical siblings, in mixed lymphocyte dendritic cell reactions (MLDCRs). RESULTS: We show that CD4+ T-cell clones, specific for the mHag H-Y, can be generated in vitro. These clones were derived from a gender-mismatched positive MLDCR pair of HLA-identical siblings and were restricted by the HLA DQB1*0502 molecule. In addition, these CD4+ T clones were also able to lyse allogeneic targets with the same pattern of restriction and specificity than helper function. Finally, acute myeloid leukemia (AML) blast cells were susceptible to lysis by these clones. CONCLUSIONS: Altogether, these results predict that Mo-DCs could help to generate class II-associated, mHag-specific, T-cell lines or clones in vitro, between healthy blood donors, without any need of transplantation-mediated immunization.     

Superior inhibition of alloantibody responses with selective CD28 blockade is CTLA-4 dependent and T follicular helper cell specific

Anti-donor antibodies cause immunologic injury in transplantation. CD28 blockade with CTLA-4-Ig has the ability to reduce the incidence of these donor-specific antibodies (DSA), but its mechanism is suboptimal for the inhibition of alloimmunity in that CTLA-4-Ig blocks both CD28 costimulation and CTLA-4 coinhibition. Thus selective CD28 blockade that spares CTLA-4 has potential to result in improved inhibition of humoral alloimmunity. To test this possibility, we utilized a full allogeneic mismatch murine transplant model and T follicular helper (Tfh):B cell co-culture system. We observed that selective blockade with an anti-CD28 domain antibody (dAb) compared to CTLA-4-Ig led to superior inhibition of Tfh cell, germinal center, and DSA responses in vivo and better control of B cell responses in vitro. CTLA-4 blockade enhanced the humoral alloresponse and, in combination with anti-CD28 dAb, abrogated the effects of selective blockade. This CTLA-4-dependent inhibition was Tfh cell specific in that CTLA-4 expression by Tfh cells was necessary and sufficient for the improved humoral inhibition observed with selective CD28 blockade. As CD28 blockade attracts interest for control of alloantibodies in the clinic, these data support selective CD28 blockade as a superior strategy to address DSA via the sparing of CTLA-4 and more potent targeting of Tfh cells.     

转Survivin基因树突状细胞抗消化道肿瘤的免疫效应研究

目的　研究转染Survivin的树突状细胞 (DC)在体外诱导高效而特异的抗消化道肿瘤免疫效应。方法　用脂质体作为介质 ,将Survivin基因转染入DC ,用Westernblot法检测培养上清Survivin的表达 ,检测这种DC分泌细胞因子白介素 (IL 12 )、肿瘤坏死因子 (TNF) α的功能 ,以及表面分子CD1a、CD83、MHcⅡ、CD80、CD86表达的高低 ,用MTT法诱导人特异的细胞毒性T淋巴细胞 (CTLs)的能力。结果　培养上清中均可以检测到Survivin表达 ;转基因DC的上清IL 12、TNF α两种细胞因子含量为 (2 65 .2± 3 2 .7)ng/L和(4 3 7.1± 83 .5 )ng/L明显比单纯DC组高(P <0 .0 5 ) ;转基因DC表面高表达CD1a、CD83、MHCⅡ、CD80、CD86;转基因的DC提呈的T细胞对胃癌细胞、结肠癌细胞、胆管癌细胞杀伤率分别为 :65 %、77%、85 % ,而未修饰的单纯DC杀伤作用较低。结论　Survivin基因转染修饰的DC能诱导细胞毒性T淋巴细胞的特异性 ,显著地提高DC的抗原提呈功能 ,体外能诱导高效而特异的抗癌免疫效应。     

转染肿瘤mRNA的树突状细胞疫苗诱导抗肝癌免疫研究

目的探讨转染原发性肝癌(HCC)mRNA的树突状细胞(DC)能否诱导抗肿瘤特异性细胞毒性T淋巴细胞(CTL)。方法采用HCC患者外周血单核细胞(PBMC)体外刺激分化为DC细胞；从人肝癌HepG-2细胞和3例HCC患者的肝癌组织中体外扩增mRNA。以mRNA转染DC细胞，并与PBMC混合培养诱导扩增CTL。流式细胞计数仪检测培养细胞中CD3^ 、CD4^ 、CD8^ 细胞的比例。^51Cr释放法测定CTL的杀瘤活性。结果经扩增人肝癌HepG-2mRNA和2例AFP( )患者的AFP( )HCCmRNA诱导3周后，CD3^ 、CD8^ 细胞占淋巴细胞总数由诱导前的27．8％、26．5％、29．6％升高至89．3％、73．6％、86．8％；而经扩增AFP(-)HCCmRNA诱导3周后，CD3^ 、CD8^ 细胞占淋巴细胞总数由诱导前的25．4％升高至53．6％。转染HepG-2细胞和AFP( )的患者HCCmRNA的DC诱导的CTL对HepG-2细胞杀瘤活性明显高于AFP(-)的患者，其杀瘤特性由MHC-I限制的CD8^ T细胞所介导。结论HCCmRNA体外转染DC能诱导肿瘤特异性CTL，可为肝癌的免疫治疗提供新的有效手段。     

负载肾癌肿瘤裂解物的树突状细胞诱导产生抗原特异性细胞毒T淋巴细胞

目的　利用树突状细胞呈递肿瘤抗原的特性提高细胞毒T淋巴细胞 (CTLs)对肾癌细胞的杀伤活性。　方法　肾细胞癌患者骨髓来源的有核细胞体外经GM CSF和IL 4诱导产生树突状细胞 ,负载肿瘤裂解物后诱导自体CTLs产生。用细胞毒试验和ELISA测定CTLs杀伤活性和细胞因子的分泌。　结果　肾癌患者自体来源的DC Tuly能 (1)增加CTLs增殖 ,16d时使T细胞增殖达 4 3倍 ;(2 )上调CTLs中CD3 和CD8 T细胞群 ;(3)诱导产生的CTLs对自体肾癌细胞具有高杀伤率 ,显著高于异体肾癌和异种肿瘤细胞 (P <0 .0 5 ) ;(4)上调TNF α分泌。　结论　DCs能呈递Tuly抗原。诱导产生抗原特异性CTLs,提示DC Tuly具有为肾癌患者制作疫苗和进行特异性CTLs过继免疫治疗的临床应用前景     

T cell help in cytotoxic T lymphocyte responses. Role of the I region in helper cell induction

We have studied the in vivo induction of T helper (TH) cells that participate in the generation of cytotoxic T (TC) lymphocytes. Helper activity was measured by the ability of the cells to help resting thymic TC cell precursors develop into effector TC cells in vitro. Direct injection of allogeneic spleen cells into the footpads of mice led to the generation of alloantigen-specific helper cells in the draining popliteal lymph nodes within 4 to 6 days. Helper activity was mediated by nylon-wool-nonadherent Lyt-1+ T lymphocytes; some activity was associated with Lyt-1,2+ cells. The genetic requirements for both the induction and restimulation of C3H anti-H-2d TH cells were investigated using cells from H-2k/H-2d recombinant mice as in vivo immunogens and in vitro stimulators. Evidence is presented that shows in a direct assay that TH cells themselves are specific for I region-coded determinants. Thus, disparity at the left side of the H-2 complex (K to I-E) but not at H-2K alone was necessary and sufficient to induce and reactivate TH cells. Proliferation in mixed lymphocyte culture was measured in combinations in which TH cells were not detectable, supporting the idea that proliferation cannot be strictly considered a measurement of helper cells.     

mTORC2 deficiency in cutaneous dendritic cells potentiates CD8+ effector T cell responses and accelerates skin graft rejection

Mechanistic target of rapamycin (mTOR) complex (mTORC)1 and mTORC2 regulate the differentiation and function of immune cells. While inhibition of mTORC1 antagonizes dendritic cell (DC) differentiation and suppresses graft rejection, the role of mTORC2 in DCs in determining host responses to transplanted tissue remains undefined. Using a mouse model in which mTORC2 was deleted specifically in CD11c⁺ DCs (TORC2^DC?/?), we show that the transplant of minor histocompatibility Ag (HY)‐mismatched skin grafts from TORC2^DC?/? donors into wild‐type recipients results in accelerated rejection characterized by enhanced CD8⁺ T cell responses in the graft and regional lymphoid tissue [Correction added on January 9, 2019, after first online publication: in the previous sentence, major was changed to minor]. Similar enhancement of CD8⁺ effector T cell responses was observed in MHC‐mismatched recipients of TORC2^DC?/? grafts. Augmented CD8⁺ T cell responses were also observed in a delayed‐type hypersensitivity model in which mTORC2 was absent in cutaneous DCs. These elevated responses could be ascribed to an increased T cell stimulatory phenotype of TORC2^DC?/? and not to enhanced lymph node homing of the cells. In contrast, rejection of ovalbumin transgenic skin grafts in TORC2^DC?/? recipients was unaffected. These findings suggest that mTORC2 in skin DCs restrains effector CD8⁺ T cell responses and have implications for understanding of the influence of mTOR inhibitors that target mTORC2 in transplant.     

Alloantigen-driven T cell death mediated by Fas ligand and tumor necrosis factor-alpha is not essential for the induction of allograft acceptance

BACKGROUND: Fas ligand (FasL)-Fas and tumor necrosis factor alpha (TNFalpha)-tumor necrosis factor receptor (TNFR) interactions regulate immune responses and contribute to self-tolerance by mediating antigen-driven T cell apoptosis. It is not known whether FasL and TNFalpha, expressed by the recipient's lymphoid or nonlymphoid cells, are essential for the apoptosis of alloreactive T lymphocytes and the induction of allograft acceptance. METHODS: We compared the survival of fully allogeneic vascularized cardiac allografts between wild-type (wt) and FasL-mutant (gld) recipient mice. In addition, we studied cardiac allograft survival in gld mice injected with TNFalpha-neutralizing antibody. Allograft acceptance (graft survival >100 days) was induced by treating the recipients with CTLA4Ig, a recombinant fusion protein that blocks B7-CD28 T cell costimulation. In vivo alloantigen-driven apoptosis of mature CD4+ and CD8+ T lymphocytes was analyzed in mice repeatedly stimulated with allogeneic splenocytes. RESULTS: We found that CTLA4Ig induces 100% long-term acceptance of cardiac allografts in wt and gld mice. Similarly, CTLA4Ig induced 100% allograft acceptance in gld recipients injected with TNFalpha-neutralizing antibody. In vivo alloantigen-driven apoptosis of mature CD4+ and CD8+ T cells was significantly reduced in gld mice and in wt mice treated with anti-TNFalpha antibody. However, neutralizing TNFalpha activity in gld mice failed to abrogate alloantigen-driven T cell apoptosis. CONCLUSIONS: These data indicate that: (1) FasL and TNFalpha expression are not obligatory for the induction of long-term allograft acceptance by CTLA4Ig and (2) FasL- and TNFalpha-independent death pathways contribute to alloantigen-driven T cell apoptosis.     

Analysis of the CD40 and CD28 pathways on alloimmune responses by CD4+ T cells in vivo

BACKGROUND: Blockade of the CD40 and CD28 pathways is a powerful strategy to inhibit CD4-mediated alloimmune responses. In this study, we examine the relative roles of the CD40 and CD28 pathways on CD4-mediated allograft rejection responses, and further characterize the role of these pathways on CD4+ T-cell activation, priming for cytokine production, and cell proliferation in response to alloantigen in vivo. METHODS: BALB/c skin allografts were transplanted onto C57BL/6 Rag 1-/- recipients reconstituted with CD4 cells from CD28-/- or CD40L-/- donors. The popliteal lymph node assay was used to study the role of these pathways on CD4-cell activation and priming in vivo. To investigate the role of CD40 and CD28 blockade on CD4-cell proliferation, the fluorescein dye carboxyfluorescein diacetate succinimidyl ester was used. We performed heterotopic cardiac transplantation using CD40-/- mice to evaluate the role of CD40 on donor versus recipient cells in CD4-mediated rejection. RESULTS: B6 Rag 1-/- recipients reconstituted with CD28-/- CD4+ T cells acutely rejected allografts (median survival time 15 days), whereas recipients reconstituted with CD40L-/- CD4+ T cells had significantly prolonged survival of BALB/c skin grafts (MST 71 days). CD40L blockade was equivalent to or inferior to CD28 blockade in inhibition of in vivo CD4-cell activation, priming for cytokine production, and proliferation responses to alloantigen. BALB/c recipients depleted of CD8 cells promptly rejected donor B6 CD40-/- cardiac allografts, whereas B6 CD40-/- recipients depleted of CD8 cells had significantly prolonged survival of BALB/c wild-type cardiac allografts. CONCLUSIONS: The CD40/CD40L pathway, but not the CD28/B7 pathway, is critical for CD4-mediated rejection responses, however, the responsible mechanisms remain unclear.     

CD40 ligand increases expression of its receptor CD40 in human coronary artery endothelial cells

BACKGROUND: Recently, CD40 ligand (CD40L) and its receptor CD40 have been implicated in atherosclerosis. Clinical data showed that elevated CD40L levels are associated with a high risk of cardiovascular events. The aim of this study was to investigate whether CD40L could affect the expression of its membrane receptor CD40 as a feedback mechanism by which CD40L could enhance its functions in human coronary artery endothelial cells (HCAECs). METHODS: The HCAECs were treated with human soluble CD40L, and the messenger RNA (mRNA) and protein levels of CD40 were determined by real-time polymerase chain reaction and Western blot analysis, respectively. The specific effect of CD40L was confirmed by a blocking experiment with antibody against CD40L. Involvements of oxidative stress and mitogen-activated protein kinases (MAPKs) were also studied with antioxidant seleno-L-methionine (SeMet) and MAPK inhibitors such as extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor. RESULTS: When HCAECs were cultured with CD40L (5 microg/mL) for 24 hours, CD40 mRNA levels were increased by 79% compared with controls (P < .05). Similarly, Western blot analysis showed an 80% increase in CD40 protein levels (P < .05). The CD40L-induced increase in CD40 mRNA levels were blocked specifically by anti-CD40L antibody. Antioxidant SeMet and specific ERK1/2 inhibitor (PD98059) also effectively blocked CD40L-induced CD40 mRNA increase. CONCLUSIONS: These data demonstrate that clinically relevant concentration of CD40L increased the expression of its receptor CD40 in HCAECs. The CD40L-induced upregulation of CD40 may be mediated by oxidative stress and ERK1/2 activation. This study suggests a new mechanism by which CD40L could enhance its biologic functions in the vascular system and contribute to endothelial dysfunction and vascular disease.     

Neuroblastoma-induced inhibition of dendritic cell IL-12 production via abrogation of CD40 expression

Background/Purpose

CD40 expression by dendritic cells (DCs) critically regulates their maturation/antitumor activity. CD40-CD40 ligand (CD40L) signaling stimulates DC-mediated IL-12 production/cytotoxicity. Recent studies suggest that neuroblastoma (NB)-derived gangliosides impair DC maturation, IL-12 secretion, and NK/T-cell activity. Neuroblastoma ganglioside-mediated abrogation of CD40 expression by DC and tumor-induced tolerance has not been studied. The purpose of this study is to determine if NB inhibits DC IL-12 production via CD40. The contributory role of the NB-derived ganglioside G_M3 in this process is also examined.

Methods

Dendritic cells were generated from bone marrow of mice injected with saline (control) or murine NB. Control DCs were matured with or without G_M3. Dendritic cells were cocultured with NB cells treated with or without a ganglioside synthesis inhibitor. Dendritic cell groups were analyzed for maturation/costimulatory markers. Control and tumor-derived DC were stimulated with CD40L or Staphylococcus aureus and studied for IL-12 expression.

Results

CD40 expression on DC generated from NB bearing mice decreased by 64% (P < .001). G_M3 down-regulated DC maturation and CD40 expression. Only CD40-dependent IL-12 production was abrogated (60%, P < .01) in DC derived from NB-bearing mice. Dendritic cell capacity to synthesize IL-12 remained intact.

Conclusions

Neuroblastoma-induced inhibition of DC function may result from ganglioside-mediated CD40 signaling deficiency. Strategies to bypass/augment CD40-CD40L signaling may improve current NB immunotherapies.     

Infiltration of activated dendritic cells and T cells in renal cell carcinoma following combined cytokine immunotherapy

OBJECTIVES: In a phase I study the feasibility, toxicity and immunological effects of peri-operative cytokine immunotherapy of renal cell carcinoma were studied. Main goals were to determine the maximal tolerable dose and detailed in situ analysis of tumor infiltrates. METHODS: Fifteen patients with renal cell carcinoma, undergoing nephrectomy, received subcutaneous immunotherapy, consisting of low-dose IL-2, IFNalpha and GM-CSF, from day -3 prior, until day +5 following surgery in a dose escalation study. Infiltrates from resected tumor tissues from patients undergoing immunotherapy or control patients that underwent nephrectomy only, were examined using quantitative immunohistological analysis and 3-color immunofluorescence staining and confocal laser scanning microscope analysis. RESULTS: Toxicity was limited and the maximal tolerable dose was established. In peripheral blood an increase was found in total lymphocytes, (activated) T cells, NK cells and monocytes. Quantitative immunohistological analysis of tumor infiltrates showed enhanced numbers of CD3+ T cells, S100+ DC, CD83+ DC and IL-2 receptor positive cells (4-fold, 2-fold, 10-fold and 20-fold, respectively, compared to controls). In treated patients preferential invasion was observed of TNFalpha positive CD8+ T cells and DC, positive for DC-SIGN (CD209), CD83, CD80, IL-12 and the DC specific chemokine, DC-CK1 (CCL18). CONCLUSIONS: These findings show increased infiltration of activated, mature DC and functionally active CD8+ T cells in renal tumors, which may suggest clinical potential of cytokine immunotherapy.