In Vitro Priming Recapitulates In Vivo HIV-1 Specific T Cell Responses, Revealing Rapid Loss of Virus Reactive CD4+ T Cells in Acute HIV-1 Infection

Abstract Background BK polyomavirus (BKPyV) remains a significant cause of premature kidney transplant failure. In the absence of effective antivirals, current treatments rely on reducing immunosuppression to regain immune control over BKPyV replication. Increasing BKPyV-specific CD8 T cells correlate with clearance of BKPyV DNAemia in kidney transplant patients. We characterized a novel approach for expanding BKPyV-specific CD8 T cells in vitro using 27mer-long synthetic BKPyV peptides, different types of antigen-presenting cells, and CD4 T cells. Methods Langerhans cells and immature or mature monocyte-derived dendritic cells (Mo-DCs) were generated from peripheral blood mononuclear cells of healthy blood donors, pulsed with synthetic peptide pools consisting of 36 overlapping 27mers (27mP) or 180 15mers (15mP). BKPyV-specific CD8 T-cell responses were assessed by cytokine release assays using 15mP or immunodominant 9mers. Results BKPyV-specific CD8 T cells expanded using 27mP and required mature Mo-DCs (P = .0312) and CD4 T cells (P = .0156) for highest responses. The resulting BKPyV-specific CD8 T cells proliferated, secreted multiple cytokines including interferon γ and tumor necrosis factor α, and were functional (CD107a+/PD1–) and cytotoxic. Conclusions Synthetic 27mP permit expanding BKPyV-specific CD8 T-cell responses when pulsing mature Mo-DCs in presence of CD4 T cells, suggesting novel and safe approaches to vaccination and adoptive T-cell therapies for patients before and after kidney transplantation.

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Preferential infection and depletion of Mycobacterium tuberculosis–specific CD4 T cells after HIV-1 infection

Journal of Experimental Medicine ◽

10.1084/jem.20100090 ◽

2010 ◽

Vol 207 (13) ◽

pp. 2869-2881 ◽

Cited By ~ 155

Author(s):

Christof Geldmacher ◽

Njabulo Ngwenyama ◽

Alexandra Schuetz ◽

Constantinos Petrovas ◽

Klaus Reither ◽

...

Keyword(s):

T Cells ◽

Mycobacterium Tuberculosis ◽

Hiv Infection ◽

Cd4 T Cells ◽

Staphylococcal Enterotoxin B ◽

Opportunistic Pathogens ◽

Rapid Loss ◽

Hiv 1

HIV-1 infection results in the progressive loss of CD4 T cells. In this study, we address how different pathogen-specific CD4 T cells are affected by HIV infection and the cellular parameters involved. We found striking differences in the depletion rates between CD4 T cells to two common opportunistic pathogens, cytomegalovirus (CMV) and Mycobacterium tuberculosis (MTB). CMV-specific CD4 T cells persisted after HIV infection, whereas MTB-specific CD4 T cells were depleted rapidly. CMV-specific CD4 T cells expressed a mature phenotype and produced very little IL-2, but large amounts of MIP-1β. In contrast, MTB-specific CD4 T cells were less mature, and most produced IL-2 but not MIP-1β. Staphylococcal enterotoxin B–stimulated IL-2–producing cells were more susceptible to HIV infection in vitro than MIP-1β–producing cells. Moreover, IL-2 production was associated with expression of CD25, and neutralization of IL-2 completely abrogated productive HIV infection in vitro. HIV DNA was found to be most abundant in IL-2–producing cells, and least abundant in MIP-1β–producing MTB-specific CD4 T cells from HIV-infected subjects with active tuberculosis. These data support the hypothesis that differences in function affect the susceptibility of pathogen-specific CD4 T cells to HIV infection and depletion in vivo, providing a potential mechanism to explain the rapid loss of MTB-specific CD4 T cells after HIV infection.

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Roscovitine Prevents TCR-Mediated T Cell Clonal Expansion In-Vitro and Protects Against GvHD In-Vivo.

Blood ◽

10.1182/blood.v110.11.318.318 ◽

2007 ◽

Vol 110 (11) ◽

pp. 318-318 ◽

Cited By ~ 2

Author(s):

Lequn Li ◽

Hui Wang ◽

Vassiliki A. Boussiotis

Keyword(s):

Cell Cycle ◽

T Cells ◽

T Cell ◽

Bone Marrow Cells ◽

T Cell Responses ◽

Clonal Expansion ◽

Control Group ◽

Cell Responses

Abstract Cell cycle re-entry of quiescent T lymphocytes is required for generation of productive T cell responses. Cyclin-dependent kinases (cdk), particularly cdk2, have an essential role in cell cycle re-entry. Cdk2 promotes phosphorylation of Rb and related pocket proteins thereby reversing their ability to sequester E2F transcription factors. Besides Rb, cdk2 phosphorylates Smad2 and Smad3. Smad3 inhibits cell cycle progression from G1 to S phase, and impaired phosphorylation on the cdk-mediated sites renders it more effective in executing this function. In contrast, cdk-mediated phosphorylation of Smad3 reduces Smad3 transcriptional activity and antiproliferative function. Recently, we determined that induction of T cell tolerance resulted in impaired cdk2 activity, leading to reduced levels of Smad3 phosphorylation on cdk-specific sites and increased Smad3 antiproliferative function due to upregulation of p15. We hypothesized that pharmacologic inhibition of cdk2 during antigen-mediated T cell stimulation might provide an effective strategy to control T cell expansion and induce tolerance. (R)-roscovitine (CYC202) is a potent inhibitor of cdk2-cyclin E, which in higher concentrations also inhibits other cdk-cyclin complexes including cdk7, cdk9 and cdk5. It is currently in clinical trials as anticancer drug and recently was shown to induce long-lasting arrest of murine polycystic kidney disease. We examined the effect of roscovitine on T cell responses in vitro and in vivo. We stimulated C57BL/6 T cells with anti-CD3-plus-anti-CD28 mAbs, DO11.10 TCR-transgenic T cells with OVA peptide or C57BL/6 T cells with MHC disparate Balb/c splenocytes. Addition of roscovitine in these cultures resulted in blockade of cell proliferation without induction of apoptosis. Biochemical analysis revealed that roscovitine prevented phosphorylation of cdk2, downregulation of p27, phosphorylation of Rb and synthesis of cyclin A, suggesting an effective G1/S cell cycle block. To determine whether roscovitine could also inhibit clonal expansion of activated T cells in vivo, we employed a mouse model of GvHD. Recipient (C57BL/6 x DBA/2) F1 mice were lethally irradiated and were subsequently infused with bone marrow cells and splenocytes, as source of allogeneic T cells, from parental C57BL/6 donors. Roscovitine or vehicle-control was given at the time of allogeneic BMT and on a trice-weekly basis thereafter for a total of three weeks. Administration of roscovitine protected against acute GvHD resulting in a median survival of 49 days in the roscovitine-treated group compared to 24 days in the control group (p=0.005), and significantly less weight loss. Importantly, roscovitine treatment had no adverse effects on engraftment, resulting in full donor chimerism in the treated mice. To examine whether tolerance had been induced by in vivo treatment with roscovitine, we examined in vitro rechallenge responses. While control C57BL/6 T cells exhibited robust responses when stimulated with (C57BL/6 x DBA/2) F1 splenocytes, responses of T cells isolated from roscovitine-treated recipients against (C57BL/6 x DBA/2) F1 splenocytes were abrogated. These results indicate that roscovitine has direct effects on preventing TCR-mediated clonal expansion in vitro and in vivo and may provide a novel therapeutic approach for control of GvHD.

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Development of a System To Study CD4+-T-Cell Responses to Transgenic Ovalbumin-Expressing Toxoplasma gondii during Toxoplasmosis

Infection and Immunity ◽

10.1128/iai.72.12.7240-7246.2004 ◽

2004 ◽

Vol 72 (12) ◽

pp. 7240-7246 ◽

Cited By ~ 45

Author(s):

Marion Pepper ◽

Florence Dzierszinski ◽

Amy Crawford ◽

Christopher A. Hunter ◽

David Roos

Keyword(s):

T Cells ◽

T Cell ◽

Toxoplasma Gondii ◽

T Cell Responses ◽

Cell Receptor ◽

In Vivo Studies ◽

Cell Responses ◽

Ifn Γ

ABSTRACT The study of the immune response to Toxoplasma gondii has provided numerous insights into the role of T cells in resistance to intracellular infections. However, the complexity of this eukaryote pathogen has made it difficult to characterize immunodominant epitopes that would allow the identification of T cells with a known specificity for parasite antigens. As a consequence, analysis of T-cell responses to T. gondii has been based on characterization of the percentage of T cells that express an activated phenotype during infection and on the ability of these cells to produce cytokines in response to complex mixtures of parasite antigens. In order to study specific CD4+ T cells responses to T. gondii, recombinant parasites that express a truncated ovalbumin (OVA) protein, in either a cytosolic or a secreted form, were engineered. In vitro and in vivo studies reveal that transgenic parasites expressing secreted OVA are able to stimulate T-cell receptor-transgenic OVA-specific CD4+ T cells to proliferate, express an activated phenotype, and produce gamma interferon (IFN-γ). Furthermore, the adoptive transfer of OVA-specific T cells into IFN-γ−/− mice provided enhanced protection against infection with the OVA-transgenic (but not parental) parasites. Together, these studies establish the utility of this transgenic system to study CD4+-T-cell responses during toxoplasmosis.

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HIV-1 Reservoir Dynamics after Vaccination and Antiretroviral Therapy Interruption Are Associated with Dendritic Cell Vaccine-Induced T Cell Responses

Journal of Virology ◽

10.1128/jvi.01062-15 ◽

2015 ◽

Vol 89 (18) ◽

pp. 9189-9199 ◽

Cited By ~ 26

Author(s):

Cristina Andrés ◽

Montserrat Plana ◽

Alberto C. Guardo ◽

Carmen Alvarez-Fernández ◽

Nuria Climent ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Dendritic Cell ◽

Immune Responses ◽

Cd4 T Cells ◽

Therapeutic Vaccine ◽

T Cell Responses ◽

Therapeutic Vaccines ◽

Cell Responses ◽

Hiv 1

ABSTRACTHIV-1-specific immune responses induced by a dendritic cell (DC)-based therapeutic vaccine might have some effect on the viral reservoir. Patients on combination antiretroviral therapy (cART) were randomized to receive DCs pulsed with autologous HIV-1 (n= 24) (DC-HIV-1) or nonpulsed DCs (n= 12) (DC-control). We measured the levels of total and integrated HIV-1 DNA in CD4 T cells isolated from these patients at 6 time points: before any cART; before the first cART interruption, which was at 56 weeks before the first immunization to isolate virus for pulsing DCs; before and after vaccinations (VAC1 and VAC2); and at weeks 12 and 48 after the second cART interruption. The vaccinations did not influence HIV-1 DNA levels in vaccinated subjects. After the cART interruption at week 12 postvaccination, while total HIV-1 DNA increased significantly in both arms, integrated HIV-1 DNA did not change in vaccinees (mean of 1.8 log10to 1.9 copies/106CD4 T cells,P= 0.22) and did increase in controls (mean of 1.8 log10to 2.1 copies/106CD4 T cells,P= 0.02) (P= 0.03 for the difference between groups). However, this lack of increase of integrated HIV-1 DNA observed in the DC-HIV-1 group was transient, and at week 48 after cART interruption, no differences were observed between the groups. The HIV-1-specific T cell responses at the VAC2 time point were inversely correlated with the total and integrated HIV-1 DNA levels after cART interruption in vaccinees (r[Pearson's correlation coefficient] = −0.69,P= 0.002, andr= −0.82,P< 0.0001, respectively). No correlations were found in controls. HIV-1-specific T cell immune responses elicited by DC therapeutic vaccines drive changes in HIV-1 DNA after vaccination and cART interruption. (This study has been registered at ClinicalTrials.gov under registration no. NCT00402142.)IMPORTANCEThere is an intense interest in developing strategies to target HIV-1 reservoirs as they create barriers to curing the disease. The development of therapeutic vaccines aimed at enhancing immune-mediated clearance of virus-producing cells is of high priority. Few therapeutic vaccine clinical trials have investigated the role of therapeutic vaccines as a strategy to safely eliminate or control viral reservoirs. We recently reported that a dendritic cell-based therapeutic vaccine was able to significantly decrease the viral set point in vaccinated patients, with a concomitant increase in HIV-1-specific T cell responses. The HIV-1-specific T cell immune responses elicited by this therapeutic dendritic cell vaccine drove changes in the viral reservoir after vaccinations and significantly delayed the replenishment of integrated HIV-1 DNA after cART interruption. These data help in understanding how an immunization could shift the virus-host balance and are instrumental for better design of strategies to reach a functional cure of HIV-1 infection.

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Increasing the potency of dendritic cell based vaccines for the treatment of cancer

10.26686/wgtn.17142863 ◽

2021 ◽

Author(s):

◽

Dianne Sika-Paotonu

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Responses ◽

Cd8 T Cell ◽

Cell Responses ◽

Vaccination Strategies ◽

Monophosphoryl Lipid A ◽

Tlr Agonist

<p>Tumours can be eradicated by T cells that recognise unique tumour-associated antigens. These T cells are initially stimulated by dendritic cells (DCs) that have acquired antigens from tumour tissue. Vaccination strategies that increase the frequencies of tumour-specific T cells by enhancing the activity of DCs are being evaluated in the clinic as novel cancer therapies. Our hypothesis is that existing DC-based vaccination strategies can be improved by stimulating toll-like receptor (TLR) signalling in the DCs, and also by encouraging interactions with iNKT cells, as these two activities are known to enhance DC function. It was also hypothesised that superior T cell responses could be induced by combining these two activities together. We used the TLR 4 agonist monophosphoryl lipid A (MPL) alone and in combination with other TLR agonists to achieve effective activation of bone marrow-derived DCs (BM-DCs) cultured in-vitro, which was characterised by upregulated expression of maturation markers on the cell surface, and enhanced release of pro-inflammatory cytokines. Some TLR agonist combinations provided significantly enhanced activities in this regard, notably the combination of MPL with either the TLR 2 agonist Pam3Cys, or the TLR 7/8 agonist Resiquimod. Although in-vitro activated BM-DCs were unable to induce stronger antigen-specific CD8+ T cell responses after intravenous injection when compared to BMDCs without TLR stimulation, enhanced CD8+ T cell responses were achieved in-vivo with the co-administration of TLR ligands, implying that TLR stimulation needed to act on cells of the host. Further studies identified the langerin-expressing CD8ɑ+ splenic DC subset in the spleen as recipients of antigen that was transferred from injected cells, and that these recipients were participants in the cross-presentation and T cell priming activities driving the CD8+ T cell response after vaccination. Antigen-loaded BM-DCs carrying the NKT cell ligand ɑ-galactosylceramide (ɑ-GalCer) were found to consistently increase antigen-specific CD8+ T cell responses in-vivo, and also cytotoxic responses as seen in cytotoxic killing assays. Again, langerin-expressing CD8ɑ+ splenic DCs were shown to be involved in this response by acquiring antigen and ɑ-GalCer from the injected vaccine BM-DCs. Finally, it was possible to achieve even greater CD8+ T cell responses in-vivo by injecting BM-DCs carrying antigen and ɑ-GalCer, together with timely co-administration of the TLR agonist. These results suggest a reassessment of the activities of DC-based vaccines to include the important role of “courier” to DCs already resident in the host that can be exploited to improve vaccination outcomes.</p>

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Artificial APC-Based Generation of IL-21 Secreting CD4+ T Cells That Can Provide Help to CD8+ T Cells.

Blood ◽

10.1182/blood.v114.22.466.466 ◽

2009 ◽

Vol 114 (22) ◽

pp. 466-466

Author(s):

Makito Tanaka ◽

Marcus Butler ◽

Sascha Ansén ◽

Osamu Imataki ◽

Alla Berezovskaya ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Cd4 T Cells ◽

Binding Assay ◽

Cell Responses ◽

Large Numbers ◽

A Cell

Abstract Abstract 466 CD8+ T cells are thought to be major players in T cell immunity because of their potent direct effector function. However, many studies have demonstrated that CD4+ T cells also play a critical role by providing help which optimizes CD8+ T cell responses. In vivo experiments using murine models have suggested that common cytokine receptor γ-chain cytokines such as IL-2, IL-15 and IL-21 are mediators of this CD4+ T cell help. Previously, we generated K562-based artificial APC (aAPC) by transducing HLA-A2, CD80, and CD83. This aAPC can generate large numbers of antigen-specific CD8+ CTL with a central/effector memory phenotype and potent effector function. These CTL are surprisingly long-lived and can be maintained in vitro without any feeder cells or cloning. We are currently conducting a clinical trial where large numbers of anti-tumor CD8+ CTL generated ex vivo using this aAPC and IL-2/IL-15 are adoptively transferred to patients with advanced cancer. Early results have demonstrated that adoptively transferred anti-tumor CTL can expand and persist as memory T cells for longer than 6 months without lymphodepletion or cytokine administration. Furthermore, some patients have demonstrated objective clinical responses. These in vivo results suggest that K562-based aAPC might serve as a clinically important APC to generate large numbers of antigen-specific T cells for adoptive therapy. Based upon these observations, we have generated a K562-derived aAPC that can expand antigen-specific CD4+ T cells capable of providing help to CD8+ T cells. One challenge with the study of human HLA class II-restricted antigen-specific CD4+ T cells lies in the fact that there is no DR allele with a frequency greater than 25% in any race or ethnic extraction. To overcome this issue, we targeted HLA-DP0401 (DP4), which is positive in 64% of Caucasians and is the most frequent HLA allele in many other ethnic groups. aAPC was generated by sequentially transducing DPA1*0103, DPB1*0401, CD80 and CD83 to HLA class I-, class II-, CD54+, CD58+ K562. Using this aAPC and 57 overlapping peptides encompassing the full-length protein, we identified three DP4-restricted immunogenic epitopes derived from CMV pp65. One of the 3 epitopes, peptide #23 (aa 221-240) appeared to be an immunodominant epitope, since specific CD4+ T cells were expanded from all donors tested. A cell-based in vitro competitive binding assay confirmed that #23 binds DP4 molecules. #23-specific CD4+ T cells generated using aAPC and low dose IL-2/IL-15 were long-lived, up to 4 months in vitro without any feeder cells or cloning, and were able to recognize APC exogenously pulsed with pp65 protein. ELISPOT showed that #23-specific CD4+ T cells were able to secrete IL-2, IL-4, IFN-γbut not IL-10 in an antigen-specific manner. Interestingly, intracellular cytokine staining revealed that a fraction of IFN-γsecreting CD4+ T cells concurrently produced IL-4. Most importantly, using an aAPC expressing HLA-A2, DP4, CD80, and CD83, we were able to demonstrate that pp65-specific CD4+ T cells can provide help to pp65-specific CD8+ T cells in an antigen-specific way. Survivin is an attractive target antigen for tumor immunotherapy, since it is expressed by many tumor types and is indispensable for tumor growth. We have also successfully generated DP4-restricted Survivin-specific CD4+ T cells using this aAPC. Using a cell-based in vitro binding assay, 5 Survivin-derived peptides with high binding capacity to DP4 molecules were identified. Among these 5 peptides, peptide #90 (aa 90-104) bound DP4 most potently. aAPC pulsed with #90 was able to induce antigen-specific CD4+ T cell responses from cancer patients. These CD4+ T cells were also long-lived, up to 3 months in vitro and secreted IL-2, IL-4, and IFN-γbut not IL-10. Interestingly, IL-21 was also produced upon antigen-specific stimulation. It should be noted that our K562-based aAPC did not expand Foxp3+ regulatory T cells under the experimental conditions tested. Taken all together, we have established a K562-based aAPC to generate large numbers of HLA-DP4-restricted antigen-specific CD4+ T cells that possess longevity and functional competence. Based upon our previous success in clinical translation of K562-based aAPC for CD8+ T cells and the high prevalence of HLA-DP4, generating a clinical grade version of this aAPC for CD4+ T cells is of high priority. Disclosures: No relevant conflicts of interest to declare.

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Increasing the potency of dendritic cell based vaccines for the treatment of cancer

10.26686/wgtn.17142863.v1 ◽

2021 ◽

Author(s):

◽

Dianne Sika-Paotonu

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Responses ◽

Cd8 T Cell ◽

Cell Responses ◽

Vaccination Strategies ◽

Monophosphoryl Lipid A ◽

Tlr Agonist

<p>Tumours can be eradicated by T cells that recognise unique tumour-associated antigens. These T cells are initially stimulated by dendritic cells (DCs) that have acquired antigens from tumour tissue. Vaccination strategies that increase the frequencies of tumour-specific T cells by enhancing the activity of DCs are being evaluated in the clinic as novel cancer therapies. Our hypothesis is that existing DC-based vaccination strategies can be improved by stimulating toll-like receptor (TLR) signalling in the DCs, and also by encouraging interactions with iNKT cells, as these two activities are known to enhance DC function. It was also hypothesised that superior T cell responses could be induced by combining these two activities together. We used the TLR 4 agonist monophosphoryl lipid A (MPL) alone and in combination with other TLR agonists to achieve effective activation of bone marrow-derived DCs (BM-DCs) cultured in-vitro, which was characterised by upregulated expression of maturation markers on the cell surface, and enhanced release of pro-inflammatory cytokines. Some TLR agonist combinations provided significantly enhanced activities in this regard, notably the combination of MPL with either the TLR 2 agonist Pam3Cys, or the TLR 7/8 agonist Resiquimod. Although in-vitro activated BM-DCs were unable to induce stronger antigen-specific CD8+ T cell responses after intravenous injection when compared to BMDCs without TLR stimulation, enhanced CD8+ T cell responses were achieved in-vivo with the co-administration of TLR ligands, implying that TLR stimulation needed to act on cells of the host. Further studies identified the langerin-expressing CD8ɑ+ splenic DC subset in the spleen as recipients of antigen that was transferred from injected cells, and that these recipients were participants in the cross-presentation and T cell priming activities driving the CD8+ T cell response after vaccination. Antigen-loaded BM-DCs carrying the NKT cell ligand ɑ-galactosylceramide (ɑ-GalCer) were found to consistently increase antigen-specific CD8+ T cell responses in-vivo, and also cytotoxic responses as seen in cytotoxic killing assays. Again, langerin-expressing CD8ɑ+ splenic DCs were shown to be involved in this response by acquiring antigen and ɑ-GalCer from the injected vaccine BM-DCs. Finally, it was possible to achieve even greater CD8+ T cell responses in-vivo by injecting BM-DCs carrying antigen and ɑ-GalCer, together with timely co-administration of the TLR agonist. These results suggest a reassessment of the activities of DC-based vaccines to include the important role of “courier” to DCs already resident in the host that can be exploited to improve vaccination outcomes.</p>

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Functional analysis of peripheral and intratumoral neoantigen-specific TCRs identified in a patient with melanoma

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-002754 ◽

2021 ◽

Vol 9 (9) ◽

pp. e002754

Author(s):

Eva Bräunlein ◽

Gaia Lupoli ◽

Franziska Füchsl ◽

Esam T Abualrous ◽

Niklas de Andrade Krätzig ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Immune Responses ◽

Immune Checkpoint ◽

T Cell Responses ◽

Functional Avidity ◽

Cell Responses

BackgroundNeoantigens derived from somatic mutations correlate with therapeutic responses mediated by treatment with immune checkpoint inhibitors. Neoantigens are therefore highly attractive targets for the development of therapeutic approaches in personalized medicine, although many aspects of their quality and associated immune responses are not yet well understood. In a case study of metastatic malignant melanoma, we aimed to perform an in-depth characterization of neoantigens and respective T-cell responses in the context of immune checkpoint modulation.MethodsThree neoantigens, which we identified either by immunopeptidomics or in silico prediction, were investigated using binding affinity analyses and structural simulations. We isolated seven T-cell receptors (TCRs) from the patient’s immune repertoire recognizing these antigens. TCRs were compared in vitro by multiparametric analyses including functional avidity, multicytokine secretion, and cross-reactivity screenings. A xenograft mouse model served to study in vivo functionality of selected TCRs. We investigated the patient’s TCR repertoire in blood and different tumor-related tissues over 3 years using TCR beta deep sequencing.ResultsSelected mutated peptide ligands with proven immunogenicity showed similar binding affinities to the human leukocyte antigen complex and comparable disparity to their wild-type counterparts in molecular dynamic simulations. Nevertheless, isolated TCRs recognizing these antigens demonstrated distinct patterns in functionality and frequency. TCRs with lower functional avidity showed at least equal antitumor immune responses in vivo. Moreover, they occurred at high frequencies and particularly demonstrated long-term persistence within tumor tissues, lymph nodes and various blood samples associated with a reduced activation pattern on primary in vitro stimulation.ConclusionsWe performed a so far unique fine characterization of neoantigen-specific T-cell responses revealing defined reactivity patterns of neoantigen-specific TCRs. Our data highlight qualitative differences of these TCRs associated with function and longevity of respective T cells. Such features need to be considered for further optimization of neoantigen targeting including adoptive T-cell therapies using TCR-transgenic T cells.

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HIV-1 Vpr- and Reverse Transcription-Induced Apoptosis in Resting Peripheral Blood CD4 T Cells and Protection by Common Gamma-Chain Cytokines

Journal of Virology ◽

10.1128/jvi.01770-15 ◽

2015 ◽

Vol 90 (2) ◽

pp. 904-916 ◽

Cited By ~ 13

Author(s):

Benjamin Trinité ◽

Chi N. Chan ◽

Caroline S. Lee ◽

David N. Levy

Keyword(s):

T Cells ◽

Cell Death ◽

T Cell ◽

Reverse Transcription ◽

Peripheral Blood ◽

Cd4 T Cells ◽

Productive Infection ◽

Hiv 1

ABSTRACTHIV-1 infection leads to the progressive depletion of the CD4 T cell compartment by various known and unknown mechanisms.In vivo, HIV-1 infects both activated and resting CD4 T cells, butin vitro, in the absence of any stimuli, resting CD4 T cells from peripheral blood are resistant to infection. This resistance is generally attributed to an intracellular environment that does not efficiently support processes such as reverse transcription (RT), resulting in abortive infection. Here, we show thatin vitroHIV-1 infection of resting CD4 T cells induces substantial cell death, leading to abortive infection.In vivo, however, various microenvironmental stimuli in lymphoid and mucosal tissues provide support for HIV-1 replication. For example, common gamma-chain cytokines (CGCC), such as interleukin-7 (IL-7), render resting CD4 T cells permissible to HIV-1 infection without inducing T cell activation. Here, we find that CGCC primarily allow productive infection by preventing HIV-1 triggering of apoptosis, as evidenced by early release of cytochromecand caspase 3/7 activation. Cell death is triggered both by products of reverse transcription and by virion-borne Vpr protein, and CGCC block both mechanisms. When HIV-1 RT efficiency was enhanced by SIVmac239 Vpx protein, cell death was still observed, indicating that the speed of reverse transcription and the efficiency of its completion contributed little to HIV-1-induced cell death in this system. These results show that a major restriction on HIV-1 infection in resting CD4 T cells resides in the capacity of these cells to survive the early steps of HIV-1 infection.IMPORTANCEA major consequence of HIV-1 infection is the destruction of CD4 T cells. Here, we show that delivery of virion-associated Vpr protein and the process of reverse transcription are each sufficient to trigger apoptosis of resting CD4 T cells isolated from peripheral blood. While these 2 mechanisms have been previously described in various cell types, we show for the first time their concerted effect in inducing resting CD4 T cell depletion. Importantly, we found that cytokines such as IL-7 and IL-4, which are particularly active in sites of HIV-1 replication, protect resting CD4 T cells from these cytopathic effects and, primarily through this protection, rather than through enhancement of specific replicative steps, they promote productive infection. This study provides important new insights for the understanding of the early steps of HIV-1 infection and T cell depletion.

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