Suppression of Allogeneic Immune Responses by Human TCRαβ+ CD4− CD8− Double-Negative T Cells.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1536-1536
Author(s):  
Simon Voelkl ◽  
Regina AM Gary ◽  
Andreas Mackensen
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Transplant Rejection ◽  
Suppressor Cells ◽  
T Cell Subsets ◽  
Cell Contact ◽  
Double Negative ◽  
Regulatory T Lymphocytes ◽  
Peripheral Stem Cell Transplantation

Abstract Regulatory T lymphocytes play an important role in the maintenance of immune tolerance to self antigens and are involved in downregulating immune responses in autoimmunity, transplant rejection and tumor immunity. Numerous studies have demonstrated the existence of distinct T cell subsets with immunoregulatory properties. Recently, a novel subset of TCRαβ+ CD4− CD8− (double-negative, DN) T cells has been characterized to specifically suppress immune responses in both mice and humans. Here we demonstrate for the first time that human DN T cells are highly potent suppressor cells of allogeneic CD4+ or CD8+ T cell responses after priming with allogeneic antigen presenting cells (APC). A prerequisite for the immunosuppressive activity is the repetitive priming with allogeneic dendritic cells whereas stimulation with artificial APCs has no effect. Using a transwell system we could show that the suppressive activity against allogeneic immune responses, mediated by DN T cells, requires cell contact. In contrast to murine DN T cells, which eliminate effector T cells via a fas/fasL or perforin/granzyme pathway, human DN T cells suppress the proliferation of alloreactive T cells in an active manner. Taken together, our data indicate that human DN T cells possess strong immunosuppressive effects on alloreactive CD4+ or CD8+ T cells. DN T cells may serve to limit clonal expansion of alloantigen-specific T cells after allogeneic peripheral stem cell transplantation.

Characterization of the Immunoregulatory Function of Human TCRαβ+ CD4-CD8- Double-Negative T Cells

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2776-2776
Author(s):  
Simon Voelkl ◽  
Regina Gary ◽  
Andreas Mackensen
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Conflicts Of Interest ◽  
T Cell Responses ◽  
Treg Cells ◽  
Cell Contact ◽  
Double Negative ◽  
Suppressive Activity ◽  
Cell Responses

Abstract Abstract 2776 Regulatory T (Treg) cells have been shown to be involved in downregulating immune responses in autoimmunity, transplant rejection, and graft-versus-host disease. Moreover, the important role of Treg cells in tumor progression has also been extensively investigated and Treg-mediated immune suppression has emerged as a crucial mechanism of tumor evasion. Recently, a novel subset of TCRαβ+ CD4−CD8− (double-negative, DN) T cells has been characterized to specifically suppress immune responses in mice. Here we demonstrate that human DN T cells belong to the family of inducible Treg cells with potent suppressor activity towards CD4+ and CD8+ T-cell responses. Resting DN T cells failed to suppress responder cells, whereas antigen presenting cell (APC)-stimulated DN T-cells and freshly isolated CD4+CD25+ Treg cells revealed a strong suppressive activity. Of importance, when more potent stimulators such as allogeneic dendritic cells were used for activation of responder T cells, CD4+CD25+ Treg cells were unable to mediate any suppressor function, while APC-primed DN T cells were still able to suppress. The suppressive activity of DN T cells is neither mediated indirectly by modulation of APCs nor by competition for T-cell growth factors. Furthermore, DN T-cell mediated suppression towards responder T cells requires cell-cell contact and is TCR dependent. Based on the importance of Treg cells in tumor immunity, we determined the frequency of circulating DN T cells in patients with malignant diseases. Of interest, the DN T-cell pool revealed an increased frequency in cancer patients compared to healthy controls, indicating that these suppressor cells might limit tumor-specific T-cell responses and thereby impair tumor immunosurveillance. Taken together, our results demonstrate that human DN T cells are a new subset of inducible Treg cells exerting a very potent suppressive activity towards cellular immune responses. Further understanding of the mechanisms involved in human DN T-cell suppression may have important implications for novel immunotherapies. Disclosures: No relevant conflicts of interest to declare.

scholarly journals 413 GEN-009, a personalized neoantigen vaccine, elicits robust immune responses in individuals with advanced or metastatic solid tumors

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A438-A438
Author(s):  
Mara Shainheit ◽  
Devin Champagne ◽  
Gabriella Santone ◽  
Syukri Shukor ◽  
Ece Bicak ◽  
...  
Keyword(s):  
Clinical Trial ◽  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Solid Tumors ◽  
Ex Vivo ◽  
T Cell Responses ◽  
Checkpoint Blockade ◽  
T Cell Subsets ◽  
Cell Responses

BackgroundATLASTM is a cell-based bioassay that utilizes a cancer patient‘s own monocyte-derived dendritic cells and CD4+ and CD8+ T cells to screen their mutanome and identify neoantigens that elicit robust anti-tumor T cell responses, as well as, deleterious InhibigensTM.1 GEN-009, a personalized vaccine comprised of 4–20 ATLAS-identified neoantigens combined with Hiltonol®, harnesses the power of neoantigen-specific T cells to treat individuals with solid tumors. The safety and efficacy of GEN-009 is being assessed in a phase 1/2a clinical trial (NCT03633110).MethodsA cohort of 15 adults with solid tumors were enrolled in the study. During the screening period, patients received standard of care PD-1-based immunotherapies appropriate for their tumor type. Subsequently, patients were immunized with GEN-009 with additional doses administered at 3, 6, 12, and 24 weeks. Peripheral blood mononuclear cells (PBMCs) were collected at baseline, pre-vaccination (D1), as well as 29, 50, 92, and 176 days post first dose. Vaccine-induced immunogenicity and persistence were assessed by quantifying neoantigen-specific T cell responses in ex vivo and in vitro stimulation dual-analyte fluorospot assays. Polyfunctionality of neoantigen-specific T cells was evaluated by intracellular cytokine staining. Additionally, potential correlations between the ATLAS-identified profile and vaccine-induced immunogenicity were assessed.ResultsGEN-009 augmented T cell responses in 100% of evaluated patients, attributable to vaccine and not checkpoint blockade. Furthermore, neoantigen-induced secretion of IFNγ and/or TNFα by PBMCs, CD4+, and CD8+ T cells was observed in all patients. Responses were primarily from polyfunctional TEM cells and detectable in both CD4+ and CD8+ T cell subsets. Some patients had evidence of epitope spreading. Unique response patterns were observed for each patient with no apparent relationship between tumor types and time to emergence, magnitude or persistence of response. Ex vivo vaccine-induced immune responses were observed as early as 1 month, and in some cases, persisted for 176 days. Clinical efficacy possibly attributable to GEN-009 was observed in several patients, but no correlation has yet been identified with neoantigen number or magnitude of immune response.ConclusionsATLAS empirically identifies stimulatory neoantigens using the patient‘s own immune cells. GEN-009, which is comprised of personalized, ATLAS-identified neoantigens, elicits early, long-lasting and polyfunctional neoantigen-specific CD4+ and CD8+ T cell responses in individuals with advanced cancer. Several patients achieved clinical responses that were possibly attributable to vaccine; efforts are underway to explore T cell correlates of protection. These data support that GEN-009, in combination with checkpoint blockade, represents a unique approach to treat solid tumors.AcknowledgementsWe are grateful to the patients and their families who consented to participate in the GEN-009-101 clinical trial.Trial RegistrationNCT03633110Ethics ApprovalThis study was approved by Western Institutional Review Board, approval number 1-1078861-1. All subjects contributing samples provided signed individual informed consent.ReferenceDeVault V, Starobinets H, Adhikari S, Singh S, Rinaldi S, Classon B, Flechtner J, Lam H. Inhibigens, personal neoantigens that drive suppressive T cell responses, abrogate protection of therapeutic anti-tumor vaccines. J. Immunol 2020; 204(1 Supplement):91.15.

scholarly journals Expansion of Functional Myeloid-Derived Suppressor Cells in Controlled Human Malaria Infection

2021 ◽  
Vol 12 ◽  
Author(s):  
Carlos Lamsfus Calle ◽  
Rolf Fendel ◽  
Anurag Singh ◽  
Thomas L. Richie ◽  
Stephen L. Hoffman ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Malaria Infection ◽  
Malaria Vaccine ◽  
Suppressor Cells ◽  
T Cell Proliferation ◽  
Myeloid Derived Suppressor Cells ◽  
Controlled Human Malaria Infection

Malaria can cause life-threatening complications which are often associated with inflammatory reactions. More subtle, but also contributing to the burden of disease are chronic, often subclinical infections, which result in conditions like anemia and immunologic hyporesponsiveness. Although very frequent, such infections are difficult to study in endemic regions because of interaction with concurrent infections and immune responses. In particular, knowledge about mechanisms of malaria-induced immunosuppression is scarce. We measured circulating immune cells by cytometry in healthy, malaria-naïve, adult volunteers undergoing controlled human malaria infection (CHMI) with a focus on potentially immunosuppressive cells. Infectious Plasmodium falciparum (Pf) sporozoites (SPZ) (PfSPZ Challenge) were inoculated during two independent studies to assess malaria vaccine efficacy. Volunteers were followed daily until parasites were detected in the circulation by RT-qPCR. This allowed us to analyze immune responses during pre-patency and at very low parasite densities in malaria-naïve healthy adults. We observed a consistent increase in circulating polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) in volunteers who developed P. falciparum blood stage parasitemia. The increase was independent of preceding vaccination with a pre-erythrocytic malaria vaccine. PMN-MDSC were functional, they suppressed CD4+ and CD8+ T cell proliferation as shown by ex-vivo co-cultivation with stimulated T cells. PMN-MDSC reduced T cell proliferation upon stimulation by about 50%. Interestingly, high circulating PMN-MDSC numbers were associated with lymphocytopenia. The number of circulating regulatory T cells (Treg) and monocytic MDSC (M-MDSC) showed no significant parasitemia-dependent variation. These results highlight PMN-MDSC in the peripheral circulation as an early indicator of infection during malaria. They suppress CD4+ and CD8+ T cell proliferation in vitro. Their contribution to immunosuppression in vivo in subclinical and uncomplicated malaria will be the subject of further research. Pre-emptive antimalarial pre-treatment of vaccinees to reverse malaria-associated PMN-MDSC immunosuppression could improve vaccine response in exposed individuals.

scholarly journals High Dimensional Tissue-Based Spatial Analysis of the Tumor Microenvironment of Follicular Lymphoma Reveals Unique Immune Niches inside Malignant Follicles

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 17-18
Author(s):  
Jose C Villasboas ◽  
Patrizia Mondello ◽  
Angelo Fama ◽  
Melissa C. Larson ◽  
Andrew L. Feldman ◽  
...  
Keyword(s):  
T Cells ◽  
Spatial Distribution ◽  
T Cell ◽  
B Cells ◽  
Research Funding ◽  
Memory T Cells ◽  
Cell Types ◽  
T Cell Subsets ◽  
Cell Contact ◽  
Private Company

Background The importance of the immune system in modulating the trajectory of lymphoma outcomes has been increasingly recognized. We recently showed that CD4+ cells are associated with clinical outcomes in a prospective cohort of almost 500 patients with follicular lymphoma (FL). Specifically, we showed that the absence of CD4+ cells inside follicles was independently associated with increased risk of early clinical failure. These data suggest that the composition, as well as the spatial distribution of immune cells within the tumor microenvironment (TME), play an important role in FL. To further define the architecture of the TME in FL we analyzed a FL tumor section using the Co-Detection by Indexing (CODEX) multiplex immunofluorescence system. Methods An 8-micron section from a formalin-fixed paraffin-embedded block containing a lymph node specimen from a patient with FL was stained with a cocktail of 15 CODEX antibodies. Five regions of interest (ROIs) were imaged using a 20X air objective. Images underwent single-cell segmentation using a Unet neural network, trained on manually segmented cells (Fig 1A). Cell type assignment was done after scaling marker expression and clustering using Phenograph. Each ROI was manually masked to indicate areas inside follicles (IF) and outside follicles (OF). Relative and absolute frequencies of cell types were calculated for each region. Cellular contacts were measured as number and types of cell-cell contacts within two cellular diameters. To identify proximity communities, we clustered cells based on number and type of neighboring masks using Phenograph. The number of cell types and cellular communities were calculated inside and outside follicles after adjustment for total IF and OF areas. The significance of cell contact was measured using a random permutation test. Results We identified 13 unique cell subsets (11 immune, 1 endothelial, 1 unclassified) in the TME of our FL section (Fig. 1A). The unique phenotype of each subset was confirmed using a dimensionality reduction tool (t-SNE). The global composition of the TME varied minimally across ROIs and consisted primarily of B cells, T cells, and macrophages subsets - in decreasing order of frequency. Higher spatial heterogeneity across ROIs was observed in the frequency of T cell subsets in comparison to B cells subsets. Inspecting the spatial distribution of T cell subsets (Fig. 1B), we observed that cytotoxic T cells were primarily located in OF areas, whereas CD4+ T cells were found in both IF and OF areas. Notably, the majority of CD4+ T cells inside the follicles expressed CD45RO (memory phenotype), while most of the CD4+ T cells outside the follicles did not. Statistical analysis of the spatial distribution of CD4+ memory T cell subsets confirmed a significant increase in their frequency inside follicles compared to outside (20.4% vs 11.2%, p < 0.001; Fig. 1D). Cell-cell contact analysis (Fig 1C) showed increased homotypic contact for all cell types. We also found a higher frequency of heterotypic contact between Ki-67+CD4+ memory T cells and Ki-67+ B cells. Pairwise analysis showed these findings were statistically significant, indicating these cells are organized in niches rather than randomly distributed across image. Analysis of cellular communities (Fig. 1C) identified 13 niches, named according to the most frequent type of cell-cell contact. All CD4+ memory T cell subsets were found to belong to the same neighborhood (CD4 Memory community). Analysis of the spatial distribution of this community confirmed that these niches were more frequently located inside follicles rather than outside (26.3±4% vs 0.004%, p < 0.001, Fig. 1D). Conclusions Analysis of the TME using CODEX provides insights on the complex composition and unique architecture of this FL case. Cells were organized in a pattern characterized by (1) high degree of homotypic contact and (2) increased heterotypic interaction between activated B cells and activated CD4+ memory T cells. Spatial analysis of both individual cell subsets and cellular neighborhoods demonstrate a statistically significant increase in CD4+ memory T cells inside malignant follicles. This emerging knowledge about the specific immune-architecture of FL adds mechanistic details to our initial observation around the prognostic value of the TME in this disease. These data support future studies using modulation of the TME as a therapeutic target in FL. Figure 1 Disclosures Galkin: BostonGene: Current Employment, Patents & Royalties. Svekolkin:BostonGene: Current Employment, Current equity holder in private company, Patents & Royalties. Postovalova:BostonGene: Current Employment, Current equity holder in private company. Bagaev:BostonGene: Current Employment, Current equity holder in private company, Patents & Royalties. Ovcharov:BostonGene: Current Employment, Current equity holder in private company, Patents & Royalties. Varlamova:BostonGene: Current Employment, Current equity holder in private company, Patents & Royalties. Novak:Celgene/BMS: Research Funding. Witzig:AbbVie: Consultancy; MorphSys: Consultancy; Incyte: Consultancy; Acerta: Research Funding; Karyopharm Therapeutics: Research Funding; Immune Design: Research Funding; Spectrum: Consultancy; Celgene: Consultancy, Research Funding. Nowakowski:Nanostrings: Research Funding; Seattle Genetics: Consultancy; Curis: Consultancy; Ryvu: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other; Kymera: Consultancy; Denovo: Consultancy; Kite: Consultancy; Celgene/BMS: Consultancy, Research Funding; Roche: Consultancy, Research Funding; MorphoSys: Consultancy, Research Funding. Cerhan:BMS/Celgene: Research Funding; NanoString: Research Funding. Ansell:Trillium: Research Funding; Takeda: Research Funding; Regeneron: Research Funding; Affimed: Research Funding; Seattle Genetics: Research Funding; Bristol Myers Squibb: Research Funding; AI Therapeutics: Research Funding; ADC Therapeutics: Research Funding.

Function and expression of checkpoint inhibitors and immune agonists on immune cells in monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM) and MM and tumor-specific T lymphocytes.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. 11577-11577 ◽  
Author(s):  
Jooeun Bae ◽  
Brandon Nguyen ◽  
Yu-Tzu Tai ◽  
Teru Hideshima ◽  
Dharminder Chauhan ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Checkpoint Inhibitor ◽  
Checkpoint Inhibitors ◽  
Suppressor Cells ◽  
Treg Cells ◽  
T Cell Subsets ◽  
Direct Stimulation ◽  
Novel Therapeutic Strategies

11577 Background: Characterization of expression and function of immune regulatory molecules in tumor microenvironment will provide the framework for developing novel therapeutic strategies. Methods: We evaluated the expression and functional impact of various immuno-regulatory molecules, PD-1, PDL-1, PDL-2, LAG3, TIM3, OX40 and GITR, on the CD138+ tumor cells, myeloid derived suppressor cells (MDSC), and T cell subsets from patients with MGUS, SMM and active MM (newly diagnosed, relapsed, relapsed/refractory), and the myeloma-specific cytotoxic T lymphocytes (CTL) induced with XBP1/CD138/CS1 peptides. Results: PDL-1/PDL-2 was more highly expressed on CD138+ myeloma cells in active MM than SMM or MGUS. G-type MDSC (CD11b+CD33+HLA-DRlowCD15+). Treg cells (CD3+CD4+/CD25+FOXP3+) numbers were increased and expressed higher levels of PD1/PD-L1 in active MM than in MGUS, SMM or healthy donors. Among the checkpoint molecules (PD-1, PDL-1, PDL-2, LAG3, OX40, GITR) evaluated, PD-1 showed the highest expression on CD3+CD4+ and CD3+CD8+T cells in BMMC and PBMC from patients with active MM. Functionally, T cells from MM patients showed increased proliferation upon treatment with an individual immune agonist ( > 150%) or checkpoint inhibitor ( > 100%). Interestingly, each individual anti-checkpoint molecule induced proliferation of T cells expressing other checkpoint molecules. In addition, the blockade of PD1, LAG3 or TIM3 enhanced MM antigen-specific cytotoxicity, assessed by parameters including CD107a, granzyme B and IFN-g production, which was most prominent within the memory CTL subset of MM antigen-specific T cells. Conclusions: These results demonstrate an increased frequency of immune regulatory cells, which highly express checkpoint inhibitors in active MM. Direct stimulation with an immune agonist or blockade of a checkpoint inhibitor increased MM patients’ T cell proliferation and myeloma-specific CTL function, supporting development of combination immune regulatory therapies to improve patient outcome in MM.

scholarly journals Antigen- and receptor-driven regulatory mechanisms. IV. Idiotype-bearing I-J+ suppressor T cell factors induce second-order suppressor T cells which express anti-idiotypic receptors.

1980 ◽  
Vol 151 (5) ◽  
pp. 1183-1195 ◽  
Author(s):  
M S Sy ◽  
M H Dietz ◽  
R N Germain ◽  
B Benacerraf ◽  
M I Greene
Keyword(s):  
T Cells ◽  
T Cell ◽  
Specific Binding ◽  
Suppressor Cells ◽  
T Cell Subsets ◽  
Regulatory Pathway ◽  
Spleen Cells ◽  
Suppressor T Cells ◽  
Suppressor Factor ◽  
Ig Heavy Chain

Administration of azobenzenearsonate (ABA)-coupled syngeneic spleen cells intravenously to A/J mice leads to the generation of suppressor T cells (Ts1) which exhibit specific binding to ABA-bovine serum albumin (BSA)-coated dishes. These Ts1 share idiotypic determinants with the major cross-reactive idiotype (CRI) of the anti-ABA antibodies of A/J mice, and also produce a soluble suppressor factor (TsF) bearing CRI and I-J subregion-coded determinants. Injection of this TsF into naive A/J mice elicits a second set of specific suppressor cells (Ts2) which are not lysed by anti-CRI antibody plus C, and which do not bind to ABA-BSA-coated dishes. However, in contrast with Ts1, these Ts2 do bind to plates bearing CRI+ anti-ABA immunoglobulin. Thus, Ts2 exhibit anti-idiotypic specificity. These data indicate that antigen elicits the production of a soluble T cell product bearing both variable portion of the Ig heavy chain (VH) and I-J subregion-coded determinants which serves to communicate between T cell subsets to establish an idiotype-anti-idiotype regulatory pathway.

scholarly journals Regulatory T-cell: Regulator of Host Defense in Infection

2017 ◽  
Vol 7 (1) ◽  
pp. 9 ◽  
Author(s):  
Mousa Mohammadnia-Afrouzi ◽  
Mehdi Shahbazi ◽  
Sedigheh Baleghi Damavandi ◽  
Ghasem Faghanzadeh Ganji ◽  
Soheil Ebrahimpour
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Immune Responses ◽  
Regulatory T Cell ◽  
Critical Role ◽  
The Body ◽  
Cell Contact ◽  
Infectious Agents ◽  
Activated T Cells

Based on diverse activities and production of several cytokines, T lymphocytes and T helper cells are divided into Th1, Th2, Th17 and regulatory T-cell (T regs) subsets based on diverse activities and production of several cytokines. Infectious agents can escape from host by modulation of immune responses as effector T-cells and Tregs. Thus, regulatory T-cells play a critical role in suppression of immune responses to infectious agents such as viruses, bacteria, parasites and fungi and as well as preserving immune homeostasis. However, regulatory T-cell responses can advantageous for the body by minimizing the tissue-damaging effects. The following subsets of regulatory T-cells have been recognized: natural regulatory Tcells, Th3, Tr1, CD8+ Treg, natural killer like Treg (NKTreg) cells. Among various markers of Treg cells, Forkhead family transcription factor (FOXP3) as an intracellular protein is used for discrimination between activated T reg cells and activated T-cells. FOXP3 has a central role in production, thymocyte differentiation and function of regulatory Tcells. Several mechanisms have been indicated in regulation of T reg cells. As, the suppression of T-cells via regulatory T-cells is either mediated by Cell-cell contact and Immunosuppressive cytokines (TGF-Beta, IL-10) mediated.

scholarly journals New differentiation pathway for double-negative regulatory T cells that regulates the magnitude of immune responses

Blood ◽  
2006 ◽  
Vol 109 (9) ◽  
pp. 4071-4079 ◽  
Author(s):  
Dong Zhang ◽  
Wei Yang ◽  
Nicolas Degauque ◽  
Yan Tian ◽  
Allison Mikita ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Cell Surface ◽  
Immune Responses ◽  
Lymphoid Tissues ◽  
Double Negative ◽  
Healthy Humans

Abstract Recent studies have demonstrated that in peripheral lymphoid tissues of normal mice and healthy humans, 1% to 5% of αβ T-cell receptor–positive (TCR+) T cells are CD4−CD8− (double-negative [DN]) T cells, capable of down-regulating immune responses. However, the origin and developmental pathway of DN T cells is still not clear. In this study, by monitoring CD4 expression during T-cell proliferation and differentiation, we identified a new differentiation pathway for the conversion of CD4+ T cells to DN regulatory T cells. We showed that the converted DN T cells retained a stable phenotype after restimulation and that furthermore, the disappearance of cell-surface CD4 molecules on converted DN T cells was a result of CD4 gene silencing. The converted DN T cells were resistant to activation-induced cell death (AICD) and expressed a unique set of cell-surface markers and gene profiles. These cells were highly potent in suppressing alloimmune responses both in vitro and in vivo in an antigen-specific manner. Perforin was highly expressed by the converted DN regulatory T cells and played a role in DN T-cell–mediated suppression. Our findings thus identify a new differentiation pathway for DN regulatory T cells and uncover a new intrinsic homeostatic mechanism that regulates the magnitude of immune responses. This pathway provides a novel, cell-based, therapeutic approach for preventing allograft rejection.

scholarly journals Oncogenic-Drivers Dictate Immune Responses to Control Disease Progression in Acute Myeloid Leukaemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 904-904
Author(s):  
Rebecca Austin ◽  
Megan Bywater ◽  
Jasmin Straube ◽  
Leanne T Cooper ◽  
Madeleine Headlam ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Nk Cells ◽  
Research Funding ◽  
T Cell Subsets ◽  
Transcriptional Analysis ◽  
Immune Control ◽  
Immune Microenvironment ◽  
Ifn Γ

Abstract Immunotherapy has revolutionised therapeutic approaches to fight cancer and, in certain diseases dramatically improves survival. Clinical responses to immune checkpoint blockade have in part been attributed to high mutational burden of tumours such as melanoma. High-risk acute myeloid leukaemia (AML) is defined by molecular and cytogenetic factors. AML has a low prevalence of somatic mutations and is predicted to have low immunogenicity. We aimed to determine how AMLs driven from different classes of oncogenes interact with endogenous anti-leukemic immune responses. Methods and Results We generated three oncogenically distinct models of AML: BCR-ABL+NUP98-HOXA9 (BA/NH9), MLL-AF9 (MA9), and AML1-ETO+NRASG12D (AE/NRAS), using retroviral transduced bone marrow transplanted into immune-competent, non-irradiated C57BL/6J (B6) mice or immune-deficient Rag2-/-γc-/- mice. Immunologic control of AML was dependent on the driver oncogene, as AE/NRAS AML was effectively controlled in B6, but not Rag2-/-γc-/-recipients, whereas survival of BA/NH9 AML recipients was similar between B6 and Rag2-/-γc-/-. MA9 AML had an intermediate phenotype (Figure 1A-C). To examine the mechanisms underlying immune escape in AE/NRAS, AML from immune-deficient or immune-competent hosts, was passaged through immune-competent hosts. Prior exposure to an intact immune system dramatically accelerated disease progression of AE/NRAS AML in subsequent B6 recipients, but this was not seen in passage through Rag2-/-γc-/- recipients. This demonstrates specific, functional immunoediting of AML resulting in evasion of immune control. Despite evidence of disease attenuation in immune competent hosts, functional immunoediting was not observed in MA9 AML. Antibody-mediated immune cell depletion experiments demonstrated that natural killer (NK) cells and T cells both contribute to the control AE/NRAS AML, whereas MA9 immune control was dependent on NK cells. As immunoediting was only seen in AE/NRAS model, this suggests that functional immunoediting in this model is primarily mediated by T cells. To characterise the mechanisms regulating immunoediting, we integrated proteomic and transcriptional analysis of immunoedited and non-immunoedited AE/NRAS AML. There was strong correlation between increased protein expression and transcriptional regulation. There was distinct regulation of inflammatory pathways between immunoedited and non-immunoedited AML. Immunoedited AE/NRAS cells showed increased IFN-γ-dependent response signatures, consistent with direct targeting of the leukemic cells by the immune system. Transcriptional analysis also showed modulation of expression of immune checkpoint molecules including upregulation of suppressive molecules Tim-3 and CD39 and downregulation of activating ligand CD137L. These findings were confirmed by cell-surface flow cytometry. Immunoedited AE/NRAS downregulated RAS signalling transcriptionally, with coordinate activation of MYC targets. In the murine AE/NRAS model, CD4+ and CD8+ T effector memory (TEM) cells (CD44+ CD62L-) demonstrated increased PD-1 expression compared to naïve mice. In addition, mice with high disease burden also had increased frequency of T cells co-expressing exhaustion markers PD-1, Tim-3 and LAG-3, consistent with suppression of the anti-leukemic effector immune response. To understand if these findings were relevant to AML in the clinic, we obtained single cell RNA-sequencing data from the CD45+ CD34- non-leukemic fraction of bone marrow in a patient with AML1-ETO AML at diagnosis compared to that in normal marrow. Single cell type classification and clustering using tSNE demonstrated remodelling of the immune microenvironment in AML with loss of NK cells, pre-B cells and skewing of T cell subsets. There was depletion of CD8+ TEM cells and greater proportions of CD4+ and CD8+ TEM cells expressing activation and exhaustion markers (IFN-γ, PD-1, LAG-3, TIM-3). Conclusions These data demonstrate that immune responses in AML are oncogene-specific and provide evidence that AE/NRAS AML cells undergo immunoediting over time in the presence of a competent immune microenvironment. Since AML is associated with alterations in T cell subsets, and changes in T cell activation and exhaustion states, these findings may inform translational strategies to use immunotherapies for patients with AML. Disclosures Smyth: Bristol Myers Squibb: Other: Research agreement; Tizona Therapeutics: Research Funding. Lane:Janssen: Consultancy, Research Funding; Celgene: Consultancy; Novartis: Consultancy.

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