scholarly journals Anti-CD40 Antibody Fused to CD40 Ligand Is a Superagonist Platform for Adjuvant Intrinsic DC-Targeting Vaccines

2022 ◽  
Vol 12 ◽  
Author(s):  
Valentina Ceglia ◽  
Sandra Zurawski ◽  
Monica Montes ◽  
Mitchell Kroll ◽  
Aurélie Bouteau ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Immune Responses ◽  
Class I ◽  
Agonist Activity ◽  
Cell Immunity ◽  
Hiv 1

CD40 is a potent activating receptor expressed on antigen-presenting cells (APCs) of the immune system. CD40 regulates many aspects of B and T cell immunity via interaction with CD40L expressed on activated T cells. Targeting antigens to CD40 via agonistic anti-CD40 antibody fusions promotes both humoral and cellular immunity, but current anti-CD40 antibody-antigen vaccine prototypes require co-adjuvant administration for significant in vivo efficacy. This may be a consequence of dulling of anti-CD40 agonist activity via antigen fusion. We previously demonstrated that direct fusion of CD40L to anti-CD40 antibodies confers superagonist properties. Here we show that anti-CD40-CD40L-antigen fusion constructs retain strong agonist activity, particularly for activation of dendritic cells (DCs). Therefore, we tested anti-CD40-CD40L antibody fused to antigens for eliciting immune responses in vitro and in vivo. In PBMC cultures from HIV-1-infected donors, anti-CD40-CD40L fused to HIV-1 antigens preferentially expanded HIV-1-specific CD8+ T cells versus CD4+ T cells compared to analogous anti-CD40-antigen constructs. In normal donors, anti-CD40-CD40L-mediated delivery of Influenza M1 protein elicited M1-specific T cell expansion at lower doses compared to anti-CD40-mediated delivery. Also, on human myeloid-derived dendritic cells, anti-CD40-CD40L-melanoma gp100 peptide induced more sustained Class I antigen presentation compared to anti-CD40-gp100 peptide. In human CD40 transgenic mice, anti-CD40-CD40L-HIV-1 gp140 administered without adjuvant elicited superior antibody responses compared to anti-CD40-gp140 antigen without fused CD40L. In human CD40 mice, compared to the anti-CD40 vehicle, anti-CD40-CD40L delivery of Eα 52-68 peptide elicited proliferating of TCR I-Eα 52-68 CD4+ T cells producing cytokine IFNγ. Also, compared to controls, only anti-CD40-CD40L-Cyclin D1 vaccination of human CD40 mice reduced implanted EO771.LMB breast tumor cell growth. These data demonstrate that human CD40-CD40L antibody fused to antigens maintains highly agonistic activity and generates immune responses distinct from existing low agonist anti-CD40 targeting formats. These advantages were in vitro skewing responses towards CD8+ T cells, increased efficacy at low doses, and longevity of MHC Class I peptide display; and in mouse models, a more robust humoral response, more activated CD4+ T cells, and control of tumor growth. Thus, the anti-CD40-CD40L format offers an alternate DC-targeting platform with unique properties, including intrinsic adjuvant activity.

scholarly journals The interaction of macrophage and non-macrophage tropic isolates of HIV-1 with thymic and tonsillar dendritic cells in vitro.

1996 ◽  
Vol 183 (4) ◽  
pp. 1851-1856 ◽  
Author(s):  
P U Cameron ◽  
M G Lowe ◽  
F Sotzik ◽  
A F Coughlan ◽  
S M Crowe ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cell Lines ◽  
Viral Entry ◽  
Response Selection ◽  
T Cell Lines ◽  
Hiv 1

Dendritic cells isolated from thymus and tonsil were tested for susceptibility to HIV-1 strains that are tropic for macrophages or for T cell lines. DCs were purified by cell sorting and before infection expressed high levels of CD4 and HLA-DR and lacked markers for T, B, NK cells, or macrophages. Viral entry and reverse transcription was found after pulsing with strains of HIV-1 that could infect macrophages. During the first 36 h the PCR signals for gag sequences increased in DCs and macrophages. In contrast little if any viral DNA was found after pulsing macrophages or DCs with HIV-1 that was able to infect T cell lines. DCs pulsed with HIV-1 were able to transmit infection to responding T cells during an allogeneic or superantigen response. Selection for virus able to infect lymphoid DCs and other DCs expressing CD4 and its transfer to T cells during subsequent immune responses may provide a mechanism for the observed predominance of macrophage-tropic HIV-1 after in vivo transmission.

scholarly journals Myeloid and plasmacytoid dendritic cells transfer HIV-1 preferentially to antigen-specific CD4+ T cells

2005 ◽  
Vol 201 (12) ◽  
pp. 2023-2033 ◽  
Author(s):  
Karin Loré ◽  
Anna Smed-Sörensen ◽  
Jayanand Vasudevan ◽  
John R. Mascola ◽  
Richard A. Koup
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Immune Defense ◽  
Productive Infection ◽  
Specific Memory ◽  
Cell Immunity ◽  
Hiv 1

Dendritic cells (DCs) are essential antigen-presenting cells for the induction of T cell immunity against pathogens such as human immunodeficiency virus (HIV)-1. At the same time, HIV-1 replication is strongly enhanced in DC–T cell clusters, potentially undermining this process. We found that immature CD123+ plasmacytoid DCs (PDCs) and CD11c+ myeloid DCs (MDCs) were susceptible to both a CCR5- and a CXCR4-using HIV-1 isolate in vitro and were able to efficiently transfer that infection to autologous CD4+ T cells. Soon after HIV-1 exposure, both PDCs and MDCs were able to transfer the virus to T cells in the absence of a productive infection. However, once a productive infection was established in the DCs, newly synthesized virus was predominantly spread to T cells. HIV-1 exposure of the MDCs and PDCs did not inhibit their ability to present cytomegalovirus (CMV) antigens and activate CMV-specific memory T cells. As a result, both PDCs and MDCs preferentially transmitted HIV-1 to the responding CMV antigen–specific CD4+ T cells rather than to nonresponding T cells. This suggests that the induction of antigen-specific T cell responses by DCs, a process crucial to immune defense, can lead to preferential HIV-1 infection and the deletion of responding CD4+ T cells.

scholarly journals P01.02 TLR-mediated suppression of the CCL22-CCR4 axis as a new target for tumor immunotherapy

2021 ◽  
Vol 9 (Suppl 1) ◽  
pp. A3.2-A4
Author(s):  
J Grün ◽  
I Piseddu ◽  
C Perleberg ◽  
N Röhrle ◽  
S Endres ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
B Cells ◽  
Regulatory T Cells ◽  
Type I ◽  
List Type ◽  
Gm Csf

BackgroundUnmethylated CpG-DNA is a potent ligand for the endosomal Toll-like-receptor-9, important for the immune activation to pathogen-associated molecules.1 CpG and other TLR-ligands show effective immunotherapeutic capacities in cancer treatment by inducing an antitumorigenic immunity.2 They are able to reduce tumor progression by reduction of intratumoral secretion of the immunoregulating chemokine CCL223 and subsequent recruitment of immunosuppressive regulatory T cells (Treg), which express CCR4 the only so far known receptor for CCL22.4 Our recent work has shown that CCL22 secretion by dendritic cells (DC) in the lymph node, mediates tolerance by inducing DC-Treg contacts.5 Indeed, in the absence of CCL22, immune responses to vaccination were stronger and resulted in tumor rejection.6 Therefore, we are aiming to investigate the effects of TLR-ligands on systemic CCL22 levels, elucidating all involved mechanisms to identify new targets for cancer immunotherapy.Materials and MethodsT, B and CD11c+ DCs of wildtype (wt) and RAG1-/- mice were isolated from splenocytes by magnetic-activated cell sorting for in vitro assays. Different co-cultures were incubated with CpG and GM-CSF, known as an CCL22 inducer.5 For in vivo experiments, wt mice were treated with CpG, R484 or poly(I:C) alone and in combination with GM-CSF. CCL22-levels in a number of organs were analyzed.ResultsAnalyzing the different immune cell compartments in vitro, we found that DCs in whole splenocytes secrete CCL22 during culture while DC cultured alone showed no CCL22 secretion. When treated with CpG, CCL22-levels were reduced in splenocytes, while it was induced in DC culture alone. The same results were seen when RAG splenocytes, that lack functional B and T cells, were cultured with CpG. CpG treated B cells were able to suppress CCL22 secretion by DC unlike T cells alone. Co-cultures of T and B cells treated with CpG, however, induced the strongest CCL22 suppression in DC. In vivo, we could show that all TLR ligands tested reduced CCL22 in a number of organs significantly. Furthermore, CpG showed the strongest suppression of CCL22 even in the presence of the CCL22 inducer GM-CSF.5ConclusionsWe could show that B cells with T cells mediate CCL22 suppression by TLR ligands. The fact that CpG was able to reduce CCL22 levels even in the presence of the inducer GM-CSF demonstrates the potent CCL22 suppressive capacity of TLR ligands.ReferencesO’Neill LA, et al. The history of toll-like receptors – redefining innate immunity. Nat Rev Immunol 2013;13(6):453–60.Rothenfusser S, et al. Recent advances in immunostimulatory CpG oligonucleotides. Curr Opin Mol Ther 2003;5(2):98–106.Wang S, et al. Intratumoral injection of a CpG oligonucleotide reverts resistance to PD-1 blockade by expanding multifunctional CD8+ T cells. Proc Natl Acad Sci U S A 2016;113(46): E7240–E7249.Rapp M, et al. CCL22 controls immunity by promoting regulatory T cell communication with dendritic cells in lymph nodes. J Exp Med 2019;216(5):1170–1181.Piseddu I, et al. Constitutive expression of CCL22 is mediated by T cell-derived GM-CSF. J Immunol 2020;205(8):2056–2065.Anz D, et al. Suppression of intratumoral CCL22 by type i interferon inhibits migration of regulatory T cells and blocks cancer progression. Cancer Res 2015;75(21):4483–93.Disclosure InformationJ. Grün: None. I. Piseddu: None. C. Perleberg: None. N. Röhrle: None. S. Endres: None. D. Anz: None.

scholarly journals 708 Novel ways to exploit IL-21 to augment adoptive T cell transfer therapy against tumors

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A737-A737
Author(s):  
Anna Cole ◽  
Guillermo Rangel RIvera ◽  
Aubrey Smith ◽  
Megan Wyatt ◽  
Brandon Ware ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Immune Cells ◽  
Striking Difference ◽  
T Cell Therapy ◽  
Cell Immunity ◽  
Emory University

BackgroundIL-21 enhances the anti-tumor capacity of adoptively transferred CD8+ T cells, while IL-2 and IL-15 impair T cell immunity by driving their expansion to a more differentiated status. Yet, these cytokines can act on many different immune cells. Given the potency of IL-21, we tested if this cytokine directly augments T cells or rather if it enhances other immune cells in the culture that indirectly improves T cell therapy.MethodsTo test this question, splenocytes from pmel-1 transgenic mice were used, as all CD8+ T cells express a transgenic TCR specific for tumor-antigen gp10025–33 overexpressed on melanoma. We then peptide activated naïve CD8+ T cells enriched or not from the spleen of pmel-1 mice and expanded them in the presence of IL-21 or IL-2 (10 ng/mL) for four days. Expanded pmel-1 from these various cultures were then restimulated with irradiated splenocytes pulsed with gp10025–33 and grown an additional seven days with IL-2 (10 ng/mL), irrespective of their initial cytokine condition. The in vitro memory phenotype, exhaustion profile, and cytokine secretion of these cultures were then assayed. Furthermore, mice bearing B16KVP melanoma tumors were infused with pmel-1 T cells expanded via these various approaches and compared for their relative capacity to engraft, persist, and regress tumor in vivo.ResultsInterestingly, we discovered that IL-21-treated T cells generated from bulk splenocytes are phenotypically and functionally distinct from IL-21-treated isolated T cells. Upon restimulation, IL-21-treated T cells from bulk splenocytes exhibited an exhausted phenotype that was like anergic IL-2-treated T cells. Moreover, few cells expressed CD62L but expressed heightened markers of suppression, including TIM3, PD-1, and EOMES. Moreover, they produced more effector molecules, including granzyme B and IFN-gamma. In vivo IL-21-treated T cells expanded from bulk splenocytes engrafted and persisted poorly, in turn mediating suboptimal regression of melanoma. Conversely, IL-21 dramatically bolstered the engraftment and antitumor activity of T cells only if they were first isolated from the spleen prior to their expansion and infusion into the animal.ConclusionsCollectively, our data shows that IL-21 may improve ACT therapy best when used directly on antitumor CD8+ T cells. Further studies will illuminate the mechanism behind this striking difference and determine whether other cell subsets reactive to IL-21 cause T cell dysfunction and/or reduced bioavailability. These findings are important for defining the best culture conditions in which to use IL-21 for ACT.AcknowledgementsWe would like to acknowledge Emory University, The Winship Cancer Institute, and the Pediatrics/Winship Flow Cytometry Core.Ethics ApprovalAll animal procedures were approved by the Institutional Animal Care and Use Committee of Emory University, protocol number 201900225.

scholarly journals Endogenous dendritic cells mediate the effects of intravenously injected therapeutic immunosuppressive dendritic cells in transplantation

Blood ◽  
2010 ◽  
Vol 116 (15) ◽  
pp. 2694-2705 ◽  
Author(s):  
Sherrie J. Divito ◽  
Zhiliang Wang ◽  
William J. Shufesky ◽  
Quan Liu ◽  
Olga A. Tkacheva ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Indirect Pathway ◽  
Allograft Survival ◽  
Complex Molecules ◽  
Cell Responses ◽  
Histocompatibility Complex

Abstract The prevailing idea regarding the mechanism(s) by which therapeutic immunosuppressive dendritic cells (DCs) restrain alloimmunity is based on the concept that they interact directly with antidonor T cells, inducing anergy, deletion, and/or regulation. However, this idea has not been tested in vivo. Using prototypic in vitro–generated maturation-resistant (MR) DCs, we demonstrate that once MR-DCs carrying donor antigen (Ag) are administered intravenously, they decrease the direct and indirect pathway T-cell responses and prolong heart allograft survival but fail to directly regulate T cells in vivo. Rather, injected MR-DCs are short-lived and reprocessed by recipient DCs for presentation to indirect pathway CD4+ T cells, resulting in abortive activation and deletion without detrimental effect on the number of indirect CD4+ FoxP3+ T cells, thus increasing the regulatory to effector T cell relative percentage. The effect on the antidonor response was independent of the method used to generate therapeutic DCs or their viability; and in accordance with the idea that recipient Ag-presenting cells mediate the effects of therapeutic DCs in transplantation, prolongation of allograft survival was achieved using donor apoptotic MR-DCs or those lacking surface major histocompatibility complex molecules. We therefore conclude that therapeutic DCs function as Ag-transporting cells rather than Ag-presenting cells to prolong allograft survival.

scholarly journals Repetitive Injections of Dendritic Cells Matured with Tumor Necrosis Factor α Induce Antigen-specific Protection of Mice from Autoimmunity

2001 ◽  
Vol 195 (1) ◽  
pp. 15-22 ◽  
Author(s):  
Mauritius Menges ◽  
Susanne Rößner ◽  
Constanze Voigtländer ◽  
Heike Schindler ◽  
Nicole A. Kukutsch ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Cell Immunity ◽  
Tnf Α ◽  
Factor Α ◽  
Necrosis Factor

Mature dendritic cells (DCs) are believed to induce T cell immunity, whereas immature DCs induce T cell tolerance. Here we describe that injections of DCs matured with tumor necrosis factor (TNF)-α (TNF/DCs) induce antigen-specific protection from experimental autoimmune encephalomyelitis (EAE) in mice. Maturation by TNF-α induced high levels of major histocompatibility complex class II and costimulatory molecules on DCs, but they remained weak producers of proinflammatory cytokines. One injection of such TNF/DCs pulsed with auto-antigenic peptide ameliorated the disease score of EAE. This could not be observed with immature DCs or DCs matured with lipopolysaccharide (LPS) plus anti-CD40. Three consecutive injections of peptide-pulsed TNF/DCs derived from wild-type led to the induction of peptide-specific predominantly interleukin (IL)-10–producing CD4+ T cells and complete protection from EAE. Blocking of IL-10 in vivo could only partially restore the susceptibility to EAE, suggesting an important but not exclusive role of IL-10 for EAE prevention. Notably, the protection was peptide specific, as TNF/DCs pulsed with unrelated peptide could not prevent EAE. In conclusion, this study describes that stimulation by TNF-α results in incompletely matured DCs (semi-mature DCs) which induce peptide-specific IL-10–producing T cells in vivo and prevent EAE.

scholarly journals Transcription factor Etv6 regulates functional differentiation of cross-presenting classical dendritic cells

2018 ◽  
Vol 215 (9) ◽  
pp. 2265-2278 ◽  
Author(s):  
Colleen M. Lau ◽  
Ioanna Tiniakou ◽  
Oriana A. Perez ◽  
Margaret E. Kirkling ◽  
George S. Yap ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Transcription Factor ◽  
T Cell ◽  
Cd8 T Cells ◽  
Functional Differentiation ◽  
Specific Gene ◽  
Hematopoietic Stem

An IRF8-dependent subset of conventional dendritic cells (cDCs), termed cDC1, effectively cross-primes CD8+ T cells and facilitates tumor-specific T cell responses. Etv6 is an ETS family transcription factor that controls hematopoietic stem and progenitor cell (HSPC) function and thrombopoiesis. We report that like HSPCs, cDCs express Etv6, but not its antagonist, ETS1, whereas interferon-producing plasmacytoid dendritic cells (pDCs) express both factors. Deletion of Etv6 in the bone marrow impaired the generation of cDC1-like cells in vitro and abolished the expression of signature marker CD8α on cDC1 in vivo. Moreover, Etv6-deficient primary cDC1 showed a partial reduction of cDC-specific and cDC1-specific gene expression and chromatin signatures and an aberrant up-regulation of pDC-specific signatures. Accordingly, DC-specific Etv6 deletion impaired CD8+ T cell cross-priming and the generation of tumor antigen–specific CD8+ T cells. Thus, Etv6 optimizes the resolution of cDC1 and pDC expression programs and the functional fitness of cDC1, thereby facilitating T cell cross-priming and tumor-specific responses.

scholarly journals Modulation of the CCR5 Receptor/Ligand Axis by Seminal Plasma and the Utility of In Vitro versus In Vivo Models

2019 ◽  
Vol 93 (11) ◽  
Author(s):  
Jennifer A. Juno ◽  
Kathleen M. Wragg ◽  
Anne B. Kristensen ◽  
Wen Shi Lee ◽  
Kevin J. Selva ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Seminal Plasma ◽  
Target Cells ◽  
Ccr5 Expression ◽  
Ccr5 Receptor ◽  
The Impact ◽  
Hiv 1

ABSTRACT Sexual HIV-1 transmission occurs primarily in the presence of semen. Although data from macaque studies suggest that CCR5+ CD4+ T cells are initial targets for HIV-1 infection, the impact of semen on T cell CCR5 expression and ligand production remains inconclusive. To determine if semen modulates the lymphocyte CCR5 receptor/ligand axis, primary human T cell CCR5 expression and natural killer (NK) cell anti-HIV-1 antibody-dependent beta chemokine production was assessed following seminal plasma (SP) exposure. Purified T cells produce sufficient quantities of RANTES to result in a significant decline in CCR5bright T cell frequency following 16 h of SP exposure (P = 0.03). Meanwhile, NK cells retain the capacity to produce limited amounts of MIP-1α/MIP-1β in response to anti-HIV-1 antibody-dependent stimulation (median, 9.5% MIP-1α+ and/or MIP-1β+), despite the immunosuppressive nature of SP. Although these in vitro experiments suggest that SP-induced CCR5 ligand production results in the loss of surface CCR5 expression on CD4+ T cells, the in vivo implications are unclear. We therefore vaginally exposed five pigtail macaques to SP and found that such exposure resulted in an increase in CCR5+ HIV-1 target cells in three of the animals. The in vivo data support a growing body of evidence suggesting that semen exposure recruits target cells to the vagina that are highly susceptible to HIV-1 infection, which has important implications for HIV-1 transmission and vaccine design. IMPORTANCE The majority of HIV-1 vaccine studies do not take into consideration the impact that semen exposure might have on the mucosal immune system. In this study, we demonstrate that seminal plasma (SP) exposure can alter CCR5 expression on T cells. Importantly, in vitro studies of T cells in culture cannot replicate the conditions under which immune cells might be recruited to the genital mucosa in vivo, leading to potentially erroneous conclusions about the impact of semen on mucosal HIV-1 susceptibility.

scholarly journals Dendritic cells transduced by multiply deleted HIV-1 vectors exhibit normal phenotypes and functions and elicit an HIV-specific cytotoxic T-lymphocyte response in vitro

Blood ◽  
2000 ◽  
Vol 96 (4) ◽  
pp. 1327-1333 ◽  
Author(s):  
Andreas Gruber ◽  
June Kan-Mitchell ◽  
Kelli L. Kuhen ◽  
Tetsu Mukai ◽  
Flossie Wong-Staal
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Ex Vivo ◽  
T Cell Response ◽  
Adoptive T Cell Therapy ◽  
Cytotoxic T Cell ◽  
T Cell Therapy ◽  
Hiv 1

Abstract Dendritic cells (DCs) genetically modified to continually express and present antigens may be potent physiologic adjuvants for induction of prophylactic or therapeutic immunity. We have previously shown that an env and nef deleted HIV-1 vector (HIV-1ΔEN) pseudotyped with VSV-G transduced monocyte-derived macrophages as well as CD34+ precursors of DCs. Here we extended these findings with HIV-1ΔEN to highly differentiated human DCs derived in culture from circulating monocytes (DCs). In addition, a new vector derived from HIV-1ΔEN but further deleted in its remaining accessory genes vif, vpr, and vpu(HIV-1ΔEN V3) was also tested. Both vectors efficiently transduced DCs. Transduction of DCs did not significantly alter their viability or their immunophenotype when compared with untransduced DCs. Furthermore, the phagocytic potential of immature DCs, as well as their ability to differentiate into mature DCs capable of stimulating T-cell proliferation, was not affected. Finally, DCs transduced by the HIV-1ΔEN vector were able to elicit a primary antiviral cytotoxic T-cell response in autologous CD8 T cells. These results suggest that HIV-1–based vectors expressing viral antigens may be useful for in vivo active immunization as well as ex vivo priming of cytotoxic T cells for adoptive T-cell therapy.

scholarly journals P04.06 mucosal immunization with a cDC1-targeted CTA1 adjuvant vaccine confers protection against melanoma metastasis

2020 ◽  
Vol 8 (Suppl 2) ◽  
pp. A39.1-A39
Author(s):  
M Arabpour ◽  
S Paul ◽  
R Kiffin ◽  
HG Wiktorin ◽  
K Hellstrand ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Immune Responses ◽  
Pulmonary Metastases ◽  
T Cell Immunity ◽  
Metastasis Formation ◽  
Mhc I ◽  
Mhc Ii ◽  
Cell Immunity

BackgroundSpecific targeting of anti-cancer vaccines to dendritic cells (DCs) has been shown to mount efficient immune responses against tumor cells. Classical CD103+dendritic cells (also called cDC1) have an inherent ability to cross-present antigens to CD8+ cytotoxic T cells. Here we have explored an anti-tumor vaccine that specifically targets cDC1 cells for protection against and elimination of metastatic melanoma. The vaccine contains the cholera toxin A1 subunit (CTA1) adjuvant and is targeted to cDC1 cells through an anti-CD103 single chain antibody (CD103 scFv).Material and MethodsC57BL/6 mice were injected with wild type or ovalbumin (OVA) expressing B16 melanoma cells either subcutaneously (s.c.) to establish solid tumors, or intravenously (i.v.) to allow the formation of pulmonary metastases. Before or after establishment of tumors, mice were intra-nasally inoculated with a vaccine composed of a CD103 scFv element fused to the adjuvant CTA1 and the MHC I H2kd-restricted OVA epitope SIINFEKL together with the MHC II H2kd-restricted OVA epitope p323 or just the p323 peptide alone (i.e. CTA1-SIINFEKL-p323-CD103 and CTA1-p323-CD103, respectively). Control mice were inoculated with PBS. The growth of solid tumors was carefully monitored and the development of pulmonary metastases was determined 2–3 weeks after tumor cell injection. In addition, antigen-specific T cell immunity following intranasal immunization was evaluated.ResultsTargeting MHC I and MHC II tumor cell epitopes to cDC1, via CD103 ScFv, in conjunction with the CTA1 adjuvant elicited strong tumor specific and protective CD8+ T cell responses as well as CD4+ T cell immunity. Immunization with the CTA1-SIINFEKL-p323-CD103 vaccine significantly reduced the growth of established solid B16F1-OVA melanomas (P<0.001) and potently prevented metastasis formation (P<0.01). Control immunizations with the CTA1-p323-CD103 vaccine tended to reduce metastasis, but tumor-specific CD8+ T cells were required for full therapeutic protection.ConclusionTargeting tumor specific CD8+ T cell epitopes to cDC1, in the context of a powerful adjuvant such as CTA1, leads to the development of efficient anti-tumor immune responses. Our results point towards the utility of cDC1-targeted vaccines in the treatment of established tumors or as a means to prevent metastasis formation.Disclosure InformationM. Arabpour: None. S. Paul: None. R. Kiffin: None. H.G. Wiktorin: None. K. Hellstrand: None. N. Lycke: None. A. Martner: None.

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