scholarly journals P12.03 Bi-specific T cell engagers targeting IL13Rá2 activate tumor-infiltrating lymphocytes and improve survival in pre-clinical models of glioblastoma

2019 ◽  
Vol 21 (Supplement_3) ◽  
pp. iii59-iii60
Author(s):  
M Zannikou ◽  
K C Pituch ◽  
L Ilut ◽  
I V Balyasnikova
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Glioma Cells ◽  
Negative Control ◽  
Single Chain ◽  
Activation Markers ◽  
Variable Regions ◽  
Clinical Models ◽  
Ifnγ And Tnfα

Abstract BACKGROUND The outstanding efficacy of bi-specific T-cell engagers (BiTE against hematological malignancies offers hope that they can similarly target solid tumors like GBM. In this study, we have designed a BiTE protein with specificity to the tumor-associated antigen, IL13Rα2, and investigated how BiTE protein engages a host’s T cell immune response to promote anti-glioma activity in pre-clinical models of GBM. MATERIAL AND METHODS BiTE molecule consisting of two single chain variable regions (scFv) of antibodies against either murine or human CD3ε and scFv47 against human IL13Rα2 connected through a flexible linker (BiTEIL13Rα2) were sub-cloned in a lentiviral expression cassette. The BiTE molecule (BiTEIL13Rα2off) modified to abrogate the interaction of scFv47 with IL13Rα2 served as a negative control. The BiTE proteins were isolated from the supernatants of HEK293T cells using His-Tag affinity chromatography and validated in SDS-PAGE, Western Blot, and ELISA assays. The BiTEIL13Rα2-induced T cells activation was measured in (i) cytotoxicity assay against IL13Rα2+ glioma cells, (ii) flow cytometry measuring for CD69 and CD25 T cells’ activation markers, and (iii) the production of cytokines, IFNγ and TNFα. For in vivo analysis, VmDk and C57Bl/6 mice bearing established intracranial glioma were treated systemically with BiTE proteins. The survival of the mice was recorded and analyzed using the log-rank test. RESULTS Here we show that BiTEIL13Rα2 specifically binds to IL13Rα2 but not to IL13Rα1, whereas BiTEIL13Rα2off has no binding activity to both IL13 receptors. The co-culture of naïve murine or donor’s human CD3+ T cells with IL13Rα2+ glioma cells in the presence of BiTEIL13Rα2 but not with BiTEIL13Rα2off (i) activates CD3+CD8+ T cells as judged by upregulation of CD69, CD25, and production of IFNγ and TNFα and (ii) results in concentration- and antigen-dependent cytotoxicity in glioma cells. Furthermore, a direct comparison of CD3+ T cells obtained from the peripheral blood and tumor tissue of GBM patients revealed that BiTEIL13Rα2 induces a potent cytotoxic activity of CD3+ T cells against IL13Rα2+ glioma cells. Finally, treatment of immunocompetent mice bearing IL13Rα2+ murine glioma with BiTEIL13Rα2 resulted in a higher frequency of intratumoral CD8+ T cells, and significant (p<0.05) improvement of survival over a negative control, BiTEIL13Rα2off group of mice. CONCLUSION Our data demonstrate that BiTEIL13Rα2 protein activates CD3+ T cells in an antigen-specific fashion. Furthermore, systemic treatment with BiTEIL13Rα2 protein confers a significant survival benefit in pre-clinical syngeneic glioma models, warranting investigations in other IL13Rα2-expressing cancers and translation to clinical settings.

Evaluation Of CD33 Expression and Functional Analysis Of The CD33/CD3 Bispecific BiTE® Antibody AMG 330 In Primary AML Samples

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 239-239 ◽  
Author(s):  
Christina Krupka ◽  
Peter Kufer ◽  
Roman Kischel ◽  
Gerhard Zugmaier ◽  
Jan Boegeholz ◽  
...  
Keyword(s):  
Stem Cells ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Ex Vivo ◽  
Natural Setting ◽  
Single Chain ◽  
Activation Markers ◽  
Expression Levels ◽  
Equity Ownership

Abstract Antibody-based immunotherapy represents a promising strategy to specifically target and eliminate chemoresistant leukemic cells in acute myeloid leukemia (AML). We evaluated a single-chain bispecific CD33/CD3 BiTE® antibody (AMG 330) for its suitability as immunotherapy in AML. A prerequisite for successful immunotherapeutic approaches using this molecule is the expression of CD33 on AML blasts including leukemic stem cells (LSCs). Therefore, we quantified CD33 expression on AML blasts and LSCs by flow cytometry (mean fluorescence intensity, MFI) and correlated expression intensity with cytogenetic and molecular disease characteristics in order to identify patient cohorts possibly most suited for CD33-targeted therapies. CD33 expression was detected in >99% of patient samples (n=621, MFI ratio ≥ 1.5) although highly variable. A strong correlation between high CD33 expression levels and NPM1 mutations (p<0.001) was found. In contrast, low CD33 expression levels were significantly associated with complex karyotypes and t(8,21) translocations (p<0.001). Furthermore, LSCs within the CD34+/CD38- compartment displayed CD33 at higher levels than healthy donor stem cells (p=0.047). Importantly, colony formation of CD34+/Lin-cells from healthy donors was not affected after pre-incubation with AMG 330 and T-cells. A major hurdle for measuring cytotoxic effects on AML blasts has long been that primary AML patient samples show progressive cell death within a few days ex-vivo. To simulate the natural setting of target and T-cells in AML patients, we developed a long-term culture system for AML blasts that allowed us to observe these co-cultures for up to 5 weeks. Thus, we were able to show effective elimination of AML blasts within primary samples by AMG 330-activated and expanded residual CD3+/CD45RA-/CCR7+ memory T-lymphocytes. While the functional relevance of CD33 expression levels was shown by faster lysis kinetics of CD33BRIGHT vs. CD33DIM AML cell lines in an in-vitro cytotoxicity assay potent anti-leukemic activity on primary AML blasts was observed irrespective of CD33 expression level. At low effector to target ratios (up to 1:79), the recruited T-cells lysed autologous blasts completely in the majority of samples. Further T-cell analysis showed that naive T-cells (CD45RA+/CCR7+) were not expanded by AMG 330; neither were terminally differentiated T-cells (CD45RA+/CCR7-), probably due to their poor proliferative capacity. We did not observe an increase in percentage of CD3+/CD4+/CD25+/FoxP3+regulatory T-cells in the presence of AMG 330, suggesting that these cells may not have impacted AMG 330-mediated T-cell activity in our experiments. Compared to control cultures, T-cells were shown to up-regulate the activation markers CD25, PD-1, TIM3 and LAG3 upon response to AMG 330, which was partially reversible after complete target cell elimination. However, PD-1 up-regulation did not correlate with an up-regulation of PD-L1 on AML blasts despite substantial INFγ secretion by activated T-cells. This study provides the first correlation of CD33 expression levels to a comprehensive genotype analysis in adult AML patients. While CD33 expression may vary by AML biologic subgroup, AMG 330 exposure led to lysis of AML blasts even in samples with low levels of expression. Targeting CD33 using AMG 330 in primary AML samples led to efficient T-cell activation and expansion as expected from the mechanism of action of BiTE® antibodies. The remarkable ex-vivo activity of AMG 330 supports further development of AMG 330 as an immunotherapy for patients with AML. Disclosures: Kufer: AMGEN Research (Munich) GmbH: Employment; AMGEN Inc.: Equity Ownership. Kischel:AMGEN Research (Munich) GmbH: Employment; AMGEN Inc.: Equity Ownership. Zugmaier:Amgen Research (Munich) GmbH: Employment; Amgen Inc.: Equity Ownership. Baeuerle:AMGEN Research (Munich) GmbH: Employment; AMGEN Inc.: Equity Ownership. Riethmüller:AMGEN Inc.: Equity Ownership.

Electroporation of Dicer-Substrate siRNA Duplexes Targeting Endogenous TCR Enhance Tumor Killing Activity of Wilms' Tumor 1 (WT1)-Specific TCR-Redirected Cytotoxic T Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 813-813 ◽  
Author(s):  
Diana Campillo-Davo ◽  
Fumihiro Fujiki ◽  
Johan M.J. Van den Bergh ◽  
Evelien L. Smits ◽  
Haruo Sugiyama ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Wilms Tumor ◽  
Target Cells ◽  
Wild Type ◽  
Activation Markers ◽  
Killing Activity ◽  
Ifn Γ ◽  
Mrna Electroporation

Abstract In adoptive cellular immunotherapy, T cells can be genetically engineered to express a novel T-cell receptor (TCR) that recognizes a tumor-associated antigen. However, mispairing between transgene and endogenous TCR chains may result in a reduction of transgene TCR expression and potentially harmful off-target reactivities. Here, we sought to develop a novel clinically safe strategy to promote transgene expression of a Wilms' tumor 1 (WT1)-specific TCR by Dicer-substrate small interfering RNA (DsiRNA)-mediated silencing of the endogenous TCR, using a double electroporation protocol. First, we isolated and cloned an HLA-A*0201-restricted WT1 peptide-specific TCR derived from a leukemia patient who demonstrated clinical benefit after receiving a WT1-targeted DC vaccine. Next, we produced a codon-optimized TCR sequence from the wild-type TCR construct and both TCR mRNAs were generated by in vitro transcription. TCR expression levels were validated by electroporation of TCR-deficient Jurkat J76.7 cells stably transduced with CD8 and an NFAT-driven GFP reporter gene. TCR functionality was confirmed by high expression levels of GFP (70% GFP+cells) upon TCR signaling after co-culture with WT1 peptide-pulsed T2 cells. In order to suppress the translation of endogenous TCR mRNA in CD8+ T cells, DsiRNA duplexes were designed to specifically target the constant regions of wild-type TCR α- and β-chains, but not the codon-optimized TCR. We further developed a double electroporation protocol combining DsiRNA and TCR mRNA transfection in which DsiRNA electroporation was performed 24 hours prior to TCR mRNA electroporation. Our results show more than 2-fold increase in WT1-specific TCR expression by HLA-A2/WT1 tetramer staining after DsiRNA treatment as compared to TCR mRNA electroporation only. This specific TCR expression was maintained at least 5 days after TCR mRNA electroporation in resting peripheral blood CD8+ lymphocytes from healthy donors. The enhanced TCR expression in DsiRNA-transfected CD8+T cells was also correlated with an increase of epitope recognition as shown by interferon (IFN)-γ ELISpot. To determine the killing capacity of DsiRNA/TCR mRNA-transfected CD8+ T cells against epitope-bearing target cells, we performed a flow cytometry-based cytotoxicity assay using WT1 peptide-pulsed T2 cells. Specific cytotoxicity, which was already present in WT1 TCR-transfected cells, was significantly enhanced in TCR mRNA-electroporated T cells following suppression of the endogenous TCR expression by DsiRNA treatment. Accordingly, DsiRNA-treated TCR mRNA transfected CD8+T cells presented higher levels of CD137 and CD69 activation markers and secretion of cytokines (IFN-γ and tumor necrosis factor-α), granzyme B, and perforin upon TCR triggering as compared to the non-DsiRNA treated T cells. In summary, we show a marked enhancement of transgene WT1-specific TCR expression upon silencing of the endogenous TCR using DsiRNA electroporation prior to TCR mRNA electroporation. Importantly, this enhancement in TCR expression was correlated with a significant increase in WT1-specific CD8+ T-cell killing activity, expression of CD69 and CD137 activation markers and cytokine secretion after recognition of WT1 peptide-bearing target cells. These results pave the way for developing a clinically safer strategy for T cell-based adoptive immunotherapy of patients with WT1-expressing malignancies. Disclosures No relevant conflicts of interest to declare.

scholarly journals DNA-Demethylating Agents enhance cytolytic activity of CD8+ T Cells and anti-tumor immunity

2017 ◽  
Author(s):  
Helen Loo Yau ◽  
Ankur Chakravarthy ◽  
Felipe Campos de Almeida ◽  
David Allard ◽  
Rajat Singhania ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Cd8 T Cell ◽  
Cytolytic Activity ◽  
Cell Tumor ◽  
Type I ◽  
Tumor Infiltration ◽  
Activation Markers ◽  
Viral Mimicry

AbstractRecent studies have shown that DNA methyltransferase inhibitors (DNMTi) can induce IRF7 activation and Type I/III interferon signaling through dsRNA-mediated viral mimicry in cancer cells. By performing a large pan-cancer analysis using TCGA data, we determined that IRF7 activation is associated with higher CD8+ T cell tumor infiltration and higher cytolytic activity across multiple cancer types. Accordingly, we demonstrate that DNMTi treatment results in increased CD8+ T cell tumor infiltration, enhanced cytolytic activity and CD8+ T cell dependent tumor growth inhibition. Finally, we show that DNMTi triggers a process marked by the induction of viral mimicry directly on CD8+ T cells, leading to activation of dsRNA sensing pathway, and up-regulation of T cell activation markers, effector cytokines, and Granzyme B. Taken together, our findings suggest that dsRNA sensing pathway activation in the immune compartment, through pharmacological DNA demethylation, is a viable strategy for boosting anti-tumor immune response.

scholarly journals Targeting Cbx3/HP1γ Induces LEF-1 and IL-21R to Promote Tumor-Infiltrating CD8 T-Cell Persistence

2021 ◽  
Author(s):  
To-Ha Thai ◽  
Phuong Le ◽  
Ngoc Ha ◽  
Ngan Tran ◽  
Andrew Newman ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Transcription Initiation ◽  
Cd8 T Cell ◽  
Checkpoint Blockade ◽  
Cell Based Therapy ◽  
Functional Exhaustion ◽  
Clinical Models ◽  
Therapy Target

Abstract Checkpoint blockade can reverse CD8+ T-cell functional exhaustion, and TCF-1 is essential for this process. However, identifying mechanisms that can prevent functional senescence and potentiate CD8+ T-cell persistence in checkpoint blockade non-responsive tumors remains a challenge. We demonstrate that targeting Cbx3/HP1γ causes augmented transcription initiation, chromatin remodeling at Lef1 and Il21r leading to increased transcriptional activity at these loci. Mechanistic studies show LEF-1 and IL-21R are required for Cbx3/HP1γ-deficient CD8+ effector T cells to persist resulting in improved control of ovarian cancer, melanoma and neuroblastoma in pre-clinical models. Cbx3/HP1γ-deficient CD8+ T cells enhanced persistence in the TME facilitates remodeling of the chemokine/receptor landscape that ensures their optimal tumor invasion at the expense of CD4+ Tregs. Thus, CD8+ T cells heightened effector function consequent to Cbx3/HP1γ deficiency may be distinct from functional reactivation by checkpoint blockade, implicating Cbx3/HP1γ as a viable cancer T-cell-based therapy target for resistant, non-responsive solid tumors.

scholarly journals Interleukin-15 Triggers Activation and Growth of the CD8 T-Cell Pool in Extravascular Tissues of Patients With Acquired Immunodeficiency Syndrome

Blood ◽  
1997 ◽  
Vol 90 (3) ◽  
pp. 1115-1123 ◽  
Author(s):  
Carlo Agostini ◽  
Livio Trentin ◽  
Rosaria Sancetta ◽  
Monica Facco ◽  
Cristina Tassinari ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Cd8 T Cells ◽  
Biological Activities ◽  
Interleukin 2 ◽  
Cd8 T Cell ◽  
Tissue Growth ◽  
Activation Markers ◽  
Accessory Function

Abstract The impairment of interleukin-2 (IL-2) production occurs very early after human immunodeficiency virus (HIV) infection as a consequence of the quantitative depletion of Th1 cells. Despite the shift in cytokine production, most individuals develop an oligoclonal expansion of major histocompatibility complex restricted, HIV-specific CD8+ cytotoxic T lymphocytes (CTL) in different organs, suggesting that other cytokines replace IL-2 in initiating the tissue infiltration of CD8+ T cells. In this study we show that IL-15, a product of monocyte-macrophages and non-T cells and which has overlapping biological activities with IL-2, is involved in local cell networks accounting for the activation and expansion of CD8+ T-cell pools in a highly affected organ, ie, the lung. IL-15 induced proliferation of T cells obtained from the lower respiratory tract of HIV-infected patients with T-cell alveolitis and severe depletion of CD4+ T cells. Lung lymphocytes were CD45R0+/CD8+ T cells spontaneously expressing activation markers (CD69 and HLA-DR) and equipped with the receptorial subunits which bind IL-15, notably the β and γ chains of the IL-2 receptor (IL-2R) and the recently identified IL-15 binding-protein termed IL-15Rα. Similar phenotypic findings were obtained after incubation of normal T cells with IL-15, which induced CD8+ T cells to express activation markers and to proliferate. The block of the IL-2Rβ/IL-2Rγ complex with specific monoclonal antibodies abolished the T-cell stimulatory activity of IL-15 while the combination of IL-15 and tumor necrosis factor-α upregulated the proliferative response of lung T lymphocytes. The hypothesis that the tissue growth of lung CD8+ lymphocytes may involve cytokines produced from cells other than T lymphocytes was confirmed by the evidence that pulmonary macrophages expressed high levels of IL-15 and that anti–IL-15 antibodies inhibited the accessory function of alveolar macrophages on mitogen-induced CD8+ T-cell proliferation. Together, these results suggest that macrophage-derived cytokines produced at sites of T-cell infiltration play a role in the activation of HIV-specific CD8+ T-cell–mediated immune response.

Prospective Molecular Identification of Alloreactive CTL Clones in Allogeneic Hematopoietic Stem Cell Transplantation.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 4972-4972
Author(s):  
Christine L. O’Keefe ◽  
Ronald Sobecks ◽  
Alexander Rodriguez ◽  
Julie Curtis ◽  
Elizabeth Kuckowski ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Molecular Analysis ◽  
Cd8 T Cells ◽  
T Cell Repertoire ◽  
Cell Repertoire ◽  
Activation Markers ◽  
Hematopoietic Stem ◽  
Allogeneic Hsct ◽  
Donor Cells

Abstract The process of immune recovery after allogeneic HSCT can be characterized by an often profound oligoclonality of the TCR spectrum which may reflect: 1) A decreased diversity within the T cell population or 2) Expansion of individual clones that may be caused by specific antigenic drive exerted by pathogens (e.g., CMV) or alloantigens during the process of GvHD. Novel technologies based on the molecular analysis of the TCR repertoire can be applied to study clonal responses, including multiplex amplification of rearranged TCR VB chains followed by sequencing and quantitation of their contribution to the entire T cell repertoire. We initially studied the T cell repertoire after allogeneic HSCT in sibling (N=20) and matched unrelated (N=9) transplants. VB spectratyping was performed on CD8+ T cells in 22 patients; of the expanded VB families tested, 61.2% (30 of 49) were mono- or oligoclonal by genotyping. The clonal size and structure was determined by sequencing. Immunodominant clones contributed up to 5.4% (avg. 1.4%; range 0.1–5.4%) of all CD8+ T cells, indicating that certain stimuli may drive expansion of immunodominant clones. We originally hypothesized that these expanded clones were allospecific and likely played a role in GvHD; however, we found no correlation between the presence of significant expansions and grade III/IV GvHD. Therefore, in order to identify alloreactive CTL clones and their clonotypic markers, an alternative approach was devised. The proposed technique utilizes an allostimulation step: recipient cells serve as targets to induce activation of allospecific donor cells. Donor alloreactive cells are identified by their expression of activation markers, such as CD25 or CD69. After sorting, allospecific T cells are used as a source of cDNA for identification and quantitation of allospecific clonotypes. In this fashion, we have analyzed patients undergoing allogeneic sibling and matched unrelated donor grafting (N=7). Prior to transplant, allostimulation was performed and alloreactive CD8-derived clonotypes were subjected to molecular analysis. VB families represented within alloresponsive CTL populations that were oligoclonal by genotyping were subcloned and a large number of CDR3 clones were sequenced to identify the immunodominant clonotypes. Sequences have been derived from activated CD8+ donor cells in 6 cases; an average of 4 (range 1–7) VB families per pair have been characterized.. Although the presence of multiple VB families with a diversified CDR3 spectrum suggests the polyclonal nature of alloresponsive clones, immunodominant clones were identified. A total of 13 immunodominant clonotypes have been identified in 5 patients. Five such clones were identified in one donor/recipient pair; in each pair at least one immunodominant clonotype was isolated. Up to 18 clones per VB family were sequenced, and the average expansion contributed 56% to the entire VB family (range 15–100%). Clonotype-specific primers have been designed from two expanded clones and used to detect the allospecific clones in post-transplant blood samples in one patient/donor pair. In sum, molecularly defined marker clonotypes indicative of alloresponsive CTLs in HSCT can be individually and prospectively isolated. Such clonotypes may find application in tissue and blood diagnosis of GvHD.

Activation of T Cells by Bispecific Single-Chain Construct MT103 (MEDI-538) Is Strictly Target Cell-Dependent.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3889-3889
Author(s):  
Klaus Brischwein ◽  
Scott A. Hammond ◽  
Larissa Parr ◽  
Schlereth Bernd ◽  
Mathias Locher ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Target Cell ◽  
Cell Activation ◽  
Cell Lysis ◽  
Target Cells ◽  
Single Chain ◽  
Activation Markers ◽  
Human T Cells

Abstract Background: Bispecific antibodies have been extensively studied in vitro and in vivo for their use in redirected tumor cell lysis. A particular challenge of bispecific antibody constructs recognizing the CD3 signaling complex is to achieve a controlled polyclonal activation of T-cells that, ideally, is entirely dependent on the presence of target cells. If this is not the case, systemic production of inflammatory cytokines and secondary endothelial reactions may occur as side effects, as are observed with the murine anti-human CD3e antibody OKT-3 (muromab, Orthoclone®). Here we present evidence that MT103 (or MEDI-538), a bispecific single chain antibody of the BiTE class that targets CD19 and CD3, induces T-cell activation exclusively in the presence of target cells. Material and methods: Peripheral blood mononuclear cells from healthy donors were prepared by Ficoll density centrifugation. PBMC were incubated for 24 hours with MT103 in presence or absence of specific target cells. Target cell lysis was determined by measurement of adenylate kinase activity released from lysed cells. De novo expression of activation markers CD69 and CD25 on T-cells was assessed by flow cytometry using directly conjugated monoclonal antibodies, and the concentration of cytokines in the supernatant was determined by a commercial FACS-based bead array. Results: MT103 was analyzed for conditional T-cell activation. In the presence of target-expressing cell lines, low picomolar concentrations of MT103 were sufficient to stimulate a high percentage of peripheral human T-cells to express cytokines and surface activation markers, to enter into the cell cycle and to induce redirected lysis of target cells. However, in the absence of target cells, the BiTE molecules no longer detectably activated human T-cells even at concentrations exceeding the ED50 for redirected lysis and conditional T-cell activation by more than five orders of magnitude. Conclusion: Our data show that T-cell activation by MT103 is highly conditional in that it is strictly dependent on the presence.

TET2 Regulates CD8+ T Cell Responses to Acute and Chronic Viral Infection

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 2227-2227
Author(s):  
Shannon A. Carty ◽  
Mercy Gohil ◽  
Erietta Stelekati ◽  
Lauren B. Banks ◽  
E. John Wherry ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Viral Infection ◽  
Cd8 T Cells ◽  
Cell Expansion ◽  
Cd8 T Cell ◽  
Dna Demethylation ◽  
Chronic Viral Infection ◽  
Specific Cell ◽  
Activation Markers

Abstract DNA methylation is one of the major epigenetic mechanisms that controls cellular differentiation. The ten-eleven translocation (TET) family of methylcytosine dioxygenases mediates active DNA demethylation through the oxidation of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) and subsequent intermediates. Here we demonstrate that TET2 regulates CD8+ T cell differentiation in vivo following acute and chronic viral infection. At steady-state, mice with a T-cell specific deletion of TET2 have intact thymic and peripheral T cell populations. Following acute viral infection with LCMV-Armstrong, TET2 loss enhances LCMV-specific CD8+ T cell memory differentiation in a cell-intrinsic manner without disrupting antigen-specific cell expansion or cytokine production. However, TET2-deficient memory CD8+ T cells exhibit altered recall responses with blunted re-expansion, retained expression of phenotypic memory markers and restricted re-expression of activation markers. During chronic viral infection with LCMV-clone 13, TET2 controls CD8+ T cell expansion and alters differentiation. Importantly, though mice with T-cell specific loss of TET2 developed similar levels of CD8+ T cell exhaustion as wild-type mice, TET2 loss specifically reduced PD-1 expression suggesting that TET2 may direct DNA demethylation of the PD-1 locus. Together, our data indicate that TET2 is an important regulator of CD8+ T cells following both acute and chronic viral infections and suggest targeting epigenetic regulators have potential for enhancing antiviral immunity. Disclosures No relevant conflicts of interest to declare.

scholarly journals Activation phenotype, rather than central– or effector–memory phenotype, predicts the recall efficacy of memory CD8+ T cells

2007 ◽  
Vol 204 (7) ◽  
pp. 1625-1636 ◽  
Author(s):  
Hirokazu Hikono ◽  
Jacob E. Kohlmeier ◽  
Shiki Takamura ◽  
Susan T. Wittmer ◽  
Alan D. Roberts ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Memory T Cells ◽  
Killer Cell ◽  
Effector Memory ◽  
Activation Markers ◽  
Memory Cd8 T Cells ◽  
And Migration ◽  
T Cell Subpopulations

The contributions of different subsets of memory CD8+ T cells to recall responses at mucosal sites of infection are poorly understood. Here, we analyzed the CD8+ T cell recall responses to respiratory virus infection in mice and demonstrate that activation markers, such as CD27 and CD43, define three distinct subpopulations of memory CD8+ T cells that differ in their capacities to mount recall responses. These subpopulations are distinct from effector– and central–memory subsets, coordinately express other markers associated with activation status, including CXCR3, CD127, and killer cell lectin-like receptor G1, and are superior to CD62L in predicting the capacity of memory T cells to mediate recall responses. Furthermore, the capacity of vaccines to elicit these memory T cell subpopulations predicted the efficacy of the recall response. These findings extend our understanding of how recall responses are generated and suggest that activation and migration markers define distinct, and unrelated, characteristics of memory T cells.

scholarly journals Suboptimal SARS-CoV-2-specific CD8+ T-cell response associated with the prominent HLA-A*02:01 phenotype

2020 ◽  
Author(s):  
Jennifer R Habel ◽  
Thi H O Nguyen ◽  
Carolien E van de Sandt ◽  
Jennifer A Juno ◽  
Priyanka Chaurasia ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Ex Vivo ◽  
Cd8 T Cell ◽  
Clinical Severity ◽  
Effector Memory ◽  
Cell Mediated Immunity ◽  
Cell Memory ◽  
Activation Markers

An improved understanding of human T-cell-mediated immunity in COVID-19 is important if we are to optimize therapeutic and vaccine strategies. Experience with influenza shows that infection primes CD8+ T-cell memory to shared peptides presented by common HLA types like HLA-A2. Following re-infection, cross-reactive CD8+ T-cells enhance recovery and diminish clinical severity. Stimulating peripheral blood mononuclear cells from COVID-19 convalescent patients with overlapping peptides from SARS-CoV-2 Spike, Nucleocapsid and Membrane proteins led to the clonal expansion of SARS-CoV-2-specific CD8+ and CD4+ T-cells in vitro, with CD4+ sets being typically robust. For CD8+ T-cells taken directly ex vivo, we identified two HLA-A*02:01-restricted SARS-CoV-2 epitopes, A2/S269-277 and A2/Orf1ab3183-3191. Using peptide-HLA tetramer enrichment, direct ex vivo assessment of the A2/S269+CD8+ and A2/Orf1ab3183+CD8+ populations indicated that the more prominent A2/S269+CD8+ set was detected at comparable frequency (1.3x10-5) in acute and convalescent HLA-A*02:01+ patients. But, while the numbers were higher than those found in uninfected HLA-A*02:01+ donors (2.5x10-6), they were low when compared with frequencies for influenza-specific (A2/M158) and EBV-specific (A2/BMLF1280) (1.38x10-4) populations. Phenotypic analysis ex vivo of A2/S269+CD8+ T-cells from COVID-19 convalescents showed that A2/S269+CD8+ T-cells were predominantly negative for the CD38, HLA-DR, PD-1 and CD71 activation markers, although the majority of total CD8+ T-cells were granzyme and/or perforin-positive. Furthermore, the bias towards naive, stem cell memory and central memory A2/S269+CD8+ T-cells rather than effector memory populations suggests that SARS-CoV2 infection may be compromising CD8+ T-cell activation. Priming with an appropriate vaccine may thus have great value for optimizing protective CD8+ T-cell immunity in COVID-19.

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