scholarly journals SARS-CoV-2 genome-wide T cell epitope mapping reveals immunodominance and substantial CD8+ T cell activation in COVID-19 patients

2021 ◽  
Vol 6 (58) ◽  
pp. eabf7550
Author(s):  
Sunil Kumar Saini ◽  
Ditte Stampe Hersby ◽  
Tripti Tamhane ◽  
Helle Rus Povlsen ◽  
Susana Patricia Amaya Hernandez ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
T Cell Responses ◽  
T Cell Immunity ◽  
Cell Recognition ◽  
T Cell Recognition ◽  
Cell Responses ◽  
Cell Immunity

T cells are important for effective viral clearance, elimination of virus-infected cells and long-term disease protection. To examine the full-spectrum of CD8+ T cell immunity in COVID-19, we experimentally evaluated 3141 major histocompatibility (MHC) class I-binding peptides covering the complete SARS-CoV-2 genome. Using DNA-barcoded peptide-MHC complex (pMHC) multimers combined with a T cell phenotype panel, we report a comprehensive list of 122 immunogenic and a subset of immunodominant SARS-CoV-2 T cell epitopes. Substantial CD8+ T cell recognition was observed in COVID-19 patients, with up to 27% of all CD8+ lymphocytes interacting with SARS-CoV-2-derived epitopes. Most immunogenic regions were derived from open reading frame (ORF) 1 and ORF3, with ORF1 containing most of the immunodominant epitopes. CD8+ T cell recognition of lower affinity was also observed in healthy donors toward SARS-CoV-2-derived epitopes. This pre-existing T cell recognition signature was partially overlapping with the epitope landscape observed in COVID-19 patients and may drive the further expansion of T cell responses to SARS-CoV-2 infection. Importantly the phenotype of the SARS-CoV-2-specific CD8+ T cells, revealed a strong T cell activation in COVID-19 patients, while minimal T cell activation was seen in healthy individuals. We found that patients with severe disease displayed significantly larger SARS-CoV-2-specific T cell populations compared to patients with mild diseases and these T cells displayed a robust activation profile. These results further our understanding of T cell immunity to SARS-CoV-2 infection and hypothesize that strong antigen-specific T cell responses are associated with different disease outcomes.

scholarly journals Does Antigen Glycosylation Impact the HIV-Specific T Cell Immunity?

2021 ◽  
Vol 11 ◽  
Author(s):  
Alex Olvera ◽  
Samandhy Cedeño ◽  
Anuska Llano ◽  
Beatriz Mothe ◽  
Jorge Sanchez ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Viral Infections ◽  
Ex Vivo ◽  
Viral Proteins ◽  
T Cell Immunity ◽  
Cell Recognition ◽  
T Cell Recognition ◽  
Cell Responses ◽  
Cell Immunity

It is largely unknown how post-translational protein modifications, including glycosylation, impacts recognition of self and non-self T cell epitopes presented by HLA molecules. Data in the literature indicate that O- and N-linked glycosylation can survive epitope processing and influence antigen presentation and T cell recognition. In this perspective, we hypothesize that glycosylation of viral proteins and processed epitopes contribute to the T cell response to HIV. Although there is some evidence for T cell responses to glycosylated epitopes (glyco-epitopes) during viral infections in the literature, this aspect has been largely neglected for HIV. To explore the role of glyco-epitope specific T cell responses in HIV infection we conducted in silico and ex vivo immune studies in individuals with chronic HIV infection. We found that in silico viral protein segments with potentially glycosylable epitopes were less frequently targeted by T cells. Ex vivo synthetically added glycosylation moieties generally masked T cell recognition of HIV derived peptides. Nonetheless, in some cases, addition of simple glycosylation moieties produced neo-epitopes that were recognized by T cells from HIV infected individuals. Herein, we discuss the potential importance of these observations and compare limitations of the employed technology with new methodologies that may have the potential to provide a more accurate assessment of glyco-epitope specific T cell immunity. Overall, this perspective is aimed to support future research on T cells recognizing glycosylated epitopes in order to expand our understanding on how glycosylation of viral proteins could alter host T cell immunity against viral infections.

538 Harnessing cross-dressing dendritic cells to strengthen anti-tumor immunity

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A574-A574
Author(s):  
Ellen Duong ◽  
Timothy Fessenden ◽  
Arjun Bhutkar ◽  
Stefani Spranger
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cancer Cell ◽  
Tumor Immunity ◽  
T Cell Responses ◽  
T Cell Immunity ◽  
Cell Responses ◽  
Cell Immunity ◽  
Cross Dressing

BackgroundCytotoxic (CD8+) T-cells are required for tumor eradication and durable anti-tumor immunity.1 The induction of tumor-reactive CD8+ T-cells is predominately attributed to a subset of dendritic cells (DC) called Batf3-driven DC1, given their robust ability to cross-present antigens for T-cell priming and their role in effector T-cell recruitment.2–4 Presence of the DC1 signature in tumors correlates with improved survival and response to immunotherapies.5–7 Yet, most tumors with a DC1 infiltrate still progress, suggesting that while DC1 can initiate tumor-reactive CD8+ T-cell responses, they are unable to sustain them. Therefore, there is a critical need to identify and engage additional stimulatory DC subsets to strengthen anti-tumor immunity and boost immunotherapy responses.MethodsTo identify DC subsets that drive poly-functional CD8+ T-cell responses, we compared the DC infiltrate of a spontaneously regressing tumor with a progressing tumor. Multicolor flow immunophenotyping and single-cell RNA-sequencing were used to profile the DC compartment of both tumors. IFNγ-ELISpot was performed on splenocytes to assess for systemic tumor-reactive T-cell responses. Sorted DC subsets from tumors were co-cultured with TCR-transgenic T-cells ex vivo to evaluate their stimulatory capacity. Cross-dressing (in vivo/ex vivo) was assayed by staining for transfer of tumor-derived H-2b MHC complexes to Balb/c DC, which express the H-2d haplotype. Protective systemic immunity was assayed via contralateral flank tumor outgrowth experiments.ResultsRegressor tumors were infiltrated with more cross-presenting DC1 than progressor tumors. However, tumor-reactive CD8+ T-cell responses and tumor control were preserved in Batf3-/- mice lacking DC1, indicating that anti-tumor immune responses could be induced independent of DC1. Through functional assays, we established that anti-tumor immunity against regressor tumors required CD11c+ DC and cGAS/STING-independent type-I-interferon-sensing. Single-cell RNA-sequencing of the immune infiltrate of regressor tumors revealed a novel CD11b+ DC subset expressing an interferon-stimulated gene signature (ISG+ DC). Flow studies demonstrated that ISG+ DC were more enriched in regressor tumors than progressor tumors. We showed that ISG+ DC could activate CD8+ T-cells by cross-dressing with tumor-derived peptide-MHC complexes, thereby bypassing the requirement for cross-presentation to initiate CD8+ T-cell-driven immunity. ISG+ DC highly expressed cytosolic dsRNA sensors (RIG-I/MDA5) and could be therapeutically harnessed by exogenous addition of a dsRNA analog to drive protective CD8+ T-cell responses in DC1-deficient mice.ConclusionsThe DC infiltrate in tumors can dictate the strength of anti-tumor immunity. Harnessing multiple stimulatory DC subsets, such as cross-presenting DC1 and cross-dressing ISG+ DC, provides a therapeutic opportunity to enhance anti-tumor immunity and increase immunotherapy responses.ReferencesFridman WH, et al. The immune contexture in human tumours: impact on clinical outcome. Nature Reviews Cancer 2012;12(4): p. 298–306.Hildner K, et al. Batf3 deficiency reveals a critical role for CD8alpha+ dendritic cells in cytotoxic T cell immunity. Science 2008;322(5904):p. 1097–100.Spranger S, et al. Tumor-Residing Batf3 dendritic cells are required for effector T cell trafficking and adoptive T cell therapy. Cancer Cell 2017;31(5):p. 711–723.e4.Roberts, EW, et al., Critical role for CD103(+)/CD141(+) dendritic cells bearing CCR7 for tumor antigen trafficking and priming of T cell immunity in melanoma. Cancer Cell 2016;30(2): p. 324–336.Broz ML, et al. Dissecting the tumor myeloid compartment reveals rare activating antigen-presenting cells critical for T cell immunity. Cancer Cell 2014;26(5): p. 638–52.Salmon H., et al., Expansion and activation of CD103(+) dendritic cell progenitors at the tumor site enhances tumor responses to therapeutic PD-L1 and BRAF inhibition. Immunity, 2016. 44(4): p. 924–38.Sánchez-Paulete AR, et al., Cancer immunotherapy with immunomodulatory anti-CD137 and Anti-PD-1 monoclonal antibodies requires BATF3-dependent dendritic cells. Cancer Discov, 2016;6(1):p. 71–9.

scholarly journals High Frequencies of Functional Virus-Specific CD4+ T Cells in SARS-CoV-2 Subjects With Olfactory and Taste Disorders

2021 ◽  
Vol 12 ◽  
Author(s):  
Dalila Mele ◽  
Anna Calastri ◽  
Eugenia Maiorano ◽  
Antonella Cerino ◽  
Michele Sachs ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
T Cell Responses ◽  
Control Group ◽  
Presenting Symptoms ◽  
Cell Responses ◽  
Taste Disorders ◽  
Specific Igg

Olfactory and taste disorders (OTD) are commonly found as presenting symptoms of SARS-CoV-2 infection in patients with clinically mild COVID-19. Virus-specific T cells are thought to play an important role in the clearance of SARS-CoV-2; therefore the study of T cell specific immune responses in patients with mild symptoms may help to understand their possible role in protection from severe disease. We evaluated SARS-CoV-2-specific T cell responses to four different peptide megapools covering all SARS-CoV-2 proteins during the acute phase of the disease in 33 individuals with mild or no other symptom beside OTD and in 22 age-matched patients with severe infection. A control group of 15 outpatients with OTD and consistently negative nasopharyngeal SARS-CoV-2 RNA swabs and virus-specific IgG serology was included in the study. Increased frequencies of virus-specific CD4+ and CD8+ T cells were found in SARS-CoV-2 positive patients with OTD compared with those with severe COVID-19 and with SARS-CoV-2 negative OTD individuals. Moreover, enhanced CD4+ and CD8+ T-cell activation induced by SARS-CoV-2 peptides was associated with higher interferon (IFN)γ production. Increased frequencies of Spike (S1/S2)-specific CD4+ T cells showing enhanced IFNγ secretion and granzyme B content were associated with serum spike-specific IgG in the OTD group. In conclusion, patients with SARS-CoV-2 induced OTD develop highly functional virus-specific CD4+ and CD8+ T cells during the symptomatic phase of the disease, suggesting that robust and coordinated T-cell responses provide protection against extension of COVID-19 to the lower respiratory tract.

Abstract 449: Novel Role of Bim in the Regulation of Allogeneic T-Cell Activation and Development of Transplant Vasculopathy

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
Anna von Rossum ◽  
Winnie Enns ◽  
Yu P Shi ◽  
Jonathan C Choy
Keyword(s):  
T Cells ◽  
Cell Death ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cell Activation ◽  
T Cell Responses ◽  
Intimal Thickening ◽  
Cell Responses ◽  
Transplant Vasculopathy

Transplant vasculopathy (TV) is an arteriosclerotic disease characterized by intimal thickening of allograft arteries and is a leading cause of heart transplant rejection. T cell responses towards allograft arteries are responsible for the development of TV and understanding the regulatory pathways controlling T cell activation in allograft arteries provides opportunities for the therapeutic attenuation of TV as well as other arteriosclerotic diseases. Bim is a pro-apoptotic Bcl-2 protein known to down-regulate immune responses after viral infections by inducing cell death of effector T cells but its role in regulating allogeneic T cell responses is not known. We compared cell death and alloantigen-driven activation of T cells from Bim +/+ (wild-type), Bim +/- and Bim -/- mice as well as the development of TV in these mice. Bim was required for cell death of both CD4 and CD8 T cells in response to cytokine deprivation in vitro . Unexpectedly, Bim was also required for alloantigen-induced proliferation of both CD4 and CD8 T cells as well as for IL-2 production. When TV was examined in aortic interposition grafts implanted into complete major histocompatibility complex-mismatched mice, intimal thickening was significantly reduced in Bim +/- but not Bim -/- recipients as compared to Bim +/+ counterparts. There was signficantly less CD4 T cell accumulation in the intima of arteries from Bim +/- as compared to Bim +/+ recipients but this effect was not observed in Bim -/- recipients. The accumulation of CD8 T cells in allograft arteries was not affected by differences in Bim expression. Taken together, our data support a novel role for Bim in driving T cell activation in response to allogeneic stimuli and indicate that the effects of this Bcl-2 protein in the pathogenesis of TV likely depends on its dual role in supporting T cell activation and death.

scholarly journals HCoV- and SARS-CoV-2 Cross-Reactive T Cells in CVID Patients

2020 ◽  
Vol 11 ◽  
Author(s):  
Sophie Steiner ◽  
Franziska Sotzny ◽  
Sandra Bauer ◽  
Il-Kang Na ◽  
Michael Schmueck-Henneresse ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
T Cell Responses ◽  
Cross Reactivity ◽  
T Cell Immunity ◽  
Cell Reactivity ◽  
Cd8 Cells ◽  
Cell Responses ◽  
Cell Immunity

The inability of patients with CVID to mount specific antibody responses to pathogens has raised concerns on the risk and severity of SARS-CoV-2 infection, but there might be a role for protective T cells in these patients. SARS-CoV-2 reactive T cells have been reported for SARS-CoV-2 unexposed healthy individuals. Until now, there is no data on T cell immunity to SARS-CoV-2 infection in CVID. This study aimed to evaluate reactive T cells to human endemic corona viruses (HCoV) and to study pre-existing SARS-CoV-2 reactive T cells in unexposed CVID patients. We evaluated SARS-CoV-2- and HCoV-229E and –OC43 reactive T cells in response to seven peptide pools, including spike and nucleocapsid (NCAP) proteins, in 11 unexposed CVID, 12 unexposed and 11 post COVID-19 healthy controls (HC). We further characterized reactive T cells by IFNγ, TNFα and IL-2 profiles. SARS-CoV-2 spike-reactive CD4+ T cells were detected in 7 of 11 unexposed CVID patients, albeit with fewer multifunctional (IFNγ/TNFα/IL-2) cells than unexposed HC. CVID patients had no SARS-CoV-2 NCAP reactive CD4+ T cells and less reactive CD8+ cells compared to unexposed HC. We observed a correlation between T cell reactivity against spike of SARS-CoV-2 and HCoVs in unexposed, but not post COVID-19 HC, suggesting cross-reactivity. T cell responses in post COVID-19 HC could be distinguished from unexposed HC by higher frequencies of triple-positive NCAP reactive CD4+ T cells. Taken together, SARS-CoV-2 reactive T cells are detectable in unexposed CVID patients albeit with lower recognition frequencies and polyfunctional potential. Frequencies of triple-functional reactive CD4+ cells might provide a marker to distinguish HCoV cross-reactive from SARS-CoV-2 specific T cell responses. Our data provides evidence, that anti-viral T cell immunity is not relevantly impaired in most CVID patients.

scholarly journals Vector Order Determines Protection against Pathogenic Simian Immunodeficiency Virus Infection in a Triple-Component Vaccine by Balancing CD4+ and CD8+ T-Cell Responses

2017 ◽  
Vol 91 (23) ◽  
Author(s):  
Ulrike Sauermann ◽  
Antonia Radaelli ◽  
Nicole Stolte-Leeb ◽  
Katharina Raue ◽  
Massimiliano Bissa ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
T Cell Activation ◽  
Cell Activation ◽  
T Cell Responses ◽  
Target Cells ◽  
Aids Vaccine ◽  
Cell Responses ◽  
Antibody Titers

ABSTRACT An effective AIDS vaccine should elicit strong humoral and cellular immune responses while maintaining low levels of CD4+ T-cell activation to avoid the generation of target cells for viral infection. The present study investigated two prime-boost regimens, both starting vaccination with single-cycle immunodeficiency virus, followed by two mucosal boosts with either recombinant adenovirus (rAd) or fowlpox virus (rFWPV) expressing SIVmac239 or SIVmac251 gag/pol and env genes, respectively. Finally, vectors were switched and systemically administered to the reciprocal group of animals. Only mucosal rFWPV immunizations followed by systemic rAd boost significantly protected animals against a repeated low-dose intrarectal challenge with pathogenic SIVmac251, resulting in a vaccine efficacy (i.e., risk reduction per exposure) of 68%. Delayed viral acquisition was associated with higher levels of activated CD8+ T cells and Gag-specific gamma interferon (IFN-γ)-secreting CD8+ cells, low virus-specific CD4+ T-cell responses, and low Env antibody titers. In contrast, the systemic rFWPV boost induced strong virus-specific CD4+ T-cell activity. rAd and rFWPV also induced differential patterns of the innate immune responses, thereby possibly shaping the specific immunity. Plasma CXCL10 levels after final immunization correlated directly with virus-specific CD4+ T-cell responses and inversely with the number of exposures to infection. Also, the percentage of activated CD69+ CD8+ T cells correlated with the number of exposures to infection. Differential stimulation of the immune response likely provided the basis for the diverging levels of protection afforded by the vaccine regimen. IMPORTANCE A failed phase II AIDS vaccine trial led to the hypothesis that CD4+ T-cell activation can abrogate any potentially protective effects delivered by vaccination or promote acquisition of the virus because CD4+ T helper cells, required for an effective immune response, also represent the target cells for viral infection. We compared two vaccination protocols that elicited similar levels of Gag-specific immune responses in rhesus macaques. Only the animal group that had a low level of virus-specific CD4+ T cells in combination with high levels of activated CD8+ T cells was significantly protected from infection. Notably, protection was achieved despite the lack of appreciable Env antibody titers. Moreover, we show that both the vector and the route of immunization affected the level of CD4+ T-cell responses. Thus, mucosal immunization with FWPV-based vaccines should be considered a potent prime in prime-boost vaccination protocols.

Dendritic Cell-Induced T Cell Non-Responsiveness Is Mediated by FOXP3+ and TGF-beta+IL-10+ CD4+ T Cells.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3891-3891
Author(s):  
Zwi N. Berneman ◽  
Nathalie Cools ◽  
Viggo F.I. Van Tendeloo ◽  
Marc Lenjou ◽  
Griet Nijs ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
T Cell Activation ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
T Cell Immunity ◽  
Tgf Beta ◽  
Cell Immunity

Abstract Dendritic cells (DC), the professional antigen presenting cells of the immune system, exert important functions both in induction of T cell immunity as well as of tolerance. Previously, it was accepted that the main function of immature DC (iDC) in their in vivo steady state condition is to maintain peripheral tolerance to self-antigens and that these iDC mature upon encounter of so-called danger signals and subsequently promote T cell immunity. However, a growing body of experimental evidence now indicates that traditional DC maturation can no longer be used to distinguish between tolerogenic and immunogenic properties of DC. In this study, we compared the in vitro stimulatory capacity of immature DC (iDC), cytokine cocktail-matured DC (CC-mDC) and poly I:C-matured DC (pIC-mDC) in the absence and presence of antigen. All investigated DC types could induce at least 2 subsets of regulatory T cells. We observed a significant increase in both the number of functionally suppressive transforming growth factor (TGF)-beta+ interleukin (IL)-10+ T cells as well as of CD4+CD25+FOXP3+ T cells within DC/T cell co-cultures as compared to T cell cultures without DC. The induction of these regulatory T cells correlates with in vitro T cell non-responsiveness after co-culture with iDC and CC-mDC, while stimulation with pIC-mDC resulted in reproducible cytomegalovirus pp65 or influenza M1 matrix peptide-specific T cell activation as compared to control cultures in the absence of DC. In addition, the T cell non-responsiveness after stimulation with iDC was shown to be mediated by TGF-beta and IL-10. Moreover, the suppressive capacity of CD4+ T cells activated by iDC and CC-mDC was shown to be transferable when these CD4+ T cells were added to an established T cell response. In contrast, addition of CD4+ T cells stimulated by pIC-mDC made responder T cells refractory to their suppressive activity. In conclusion, we hypothesize that DC have a complementary role in inducing both regulatory T cells and effector T cells, where the final result of antigen-specific T cell activation will depend on the activation state of the DC. This emphasizes the need for proper DC activation when T cell immunity is the desired effect, especially when used in clinical trials.

scholarly journals Visualising the interaction of CD4 T cells and DCs in the evolution of inflammatory arthritis

2018 ◽  
Vol 77 (4) ◽  
pp. 579-588 ◽  
Author(s):  
Catriona T Prendergast ◽  
Agapitos Patakas ◽  
Shaima Al-Khabouri ◽  
Claire L McIntyre ◽  
Iain B McInnes ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
T Cell Responses ◽  
Receptor Expression ◽  
Phenotypic Analysis ◽  
Necrosis Factor Alpha ◽  
Cell Responses

ObjectivesSuccessful early intervention in rheumatoid arthritis (RA) with the aim of resetting immunological tolerance requires a clearer understanding of how specificity, cellular kinetics and spatial behaviour shape the evolution of articular T cell responses. We aimed to define initial seeding of articular CD4+ T cell responses in early experimental arthritis, evaluating their dynamic behaviour and interactions with dendritic cells (DCs) in the inflamed articular environment.MethodsAntigen-induced arthritis was used to model articular inflammation. Flow cytometry and PCR of T cell receptor (TCR) diversity genes allowed phenotypic analysis of infiltrating T cells. The dynamic interactions of T cells with joint residing DCs were visualised using intravital multiphoton microscopy.ResultsInitial recruitment of antigen-specific T cells into the joint was paralleled by accumulation of CD4+ T cells with diverse antigen-receptor expression and ability to produce tumour necrosis factor alpha (TNFα) and interferon gamma (IFNγ) on mitogenic restimulation. A proportion of this infiltrate demonstrated slower motility speeds and engaged for longer periods with articular DCs in vivo. Abatacept treatment did not disrupt these interactions but did reduce T cell expression of inducible costimulatory (ICOS) molecule. We also demonstrated that non-specific CD4+ T cells could be recruited during these early articular events.ConclusionsWe demonstrate that CD4+ T cells engage with articular DCs supporting antigen specific T cell reactivation. This cellular dialogue can be targeted therapeutically to reduce local T cell activation.

scholarly journals Long-term follow-up of SARS-CoV-2 convalescents reveals distinct magnitude of spike-specific immunity after viral re-exposure and vaccination

2021 ◽  
Author(s):  
Percy Knolle ◽  
Nina Körber ◽  
Alina Priller ◽  
Sarah Yazici ◽  
Tanja Bauer ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Neutralizing Antibodies ◽  
T Cell Responses ◽  
T Cell Immunity ◽  
Cell Responses ◽  
Specific Immunity ◽  
Cell Immunity

Abstract Infection with the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is controlled by the host´s immune response1-4, but longitudinal follow-up studies of virus-specific immunity to evaluate protection from re-infection are lacking. Here, we report the results from a prospective study that started during the first wave of the COVID-19 pandemic in spring 2020, where we identified 91 convalescents from mild SARS-CoV-2 infection among 4554 health care workers. We followed the dynamics and magnitude of spike-specific immunity in convalescents during the spontaneous course over ≥ 9 months, after SARS-CoV-2 re-exposure and after BNT162b2 mRNA vaccination. Virus-neutralizing antibodies and spike-specific T cell responses with predominance of IL-2-secreting polyfunctional CD4 T cells continuously declined over 9 months, but remained detectable at low levels. After a single vaccination, convalescents simultaneously mounted strong antibody and T cell responses against the SARS-CoV-2 spike proteins. In naïve individuals, a prime vaccination induced preferentially IL-2-secreting CD4 T cells that preceded production of spike-specific virus-neutralizing antibodies after boost vaccination. Response to vaccination, however, was not homogenous. Compared to four individuals among 455 naïve vaccinees (0.9%), we identified 5/82 (6.1%) convalescents with a delayed response to vaccination. These convalescents had originally developed dysfunctional spike-specific immune responses after SARS-CoV-2 infection, and required prime and boost vaccination to develop strong spike-specific immunity. Importantly, during the second wave of the COVID-19 pandemic in fall/winter of 2021 and prior to vaccination we detected a surge of virus-neutralizing antibodies consistent with re-exposure to SARS-CoV-2 in 6 out of 82 convalescents. The selective increase in virus-neutralizing antibodies occurred without systemic re-activation of spike-specific T cell immunity, whereas a single BNT162b2 mRNA vaccination sufficed to induce strong spike-specific antibody and systemic T cell responses in the same individuals. These results support the notion that BNT162b2 mRNA vaccination synchronizes spike-specific immunity in all convalescents of mild SARS-CoV-2 infection and may provide additional protection from re-infection by inducing more rigorous stimulation of spike-specific T cell immunity than re-exposure with SARS-CoV-2.

HLA-Class I Alleles Impact Susceptibility To EBV+ Classical Hodgkin Lymphoma By Altering EBV Latent Antigen-Specific CD8+ T-Cell Immune Hierarchies

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 630-630
Author(s):  
Maher K Gandhi ◽  
Rebekah M Brennan ◽  
Leesa Wockner ◽  
Pratip K Chattopadhyay ◽  
Mario Roederer ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Ex Vivo ◽  
T Cell Responses ◽  
Hla Class I ◽  
Cd8 T Cell ◽  
T Cell Immunity ◽  
Class I ◽  
Cell Responses ◽  
Cell Immunity

Abstract In Epstein-Barr virus (EBV) classical Hodgkin lymphoma (EBV+ cHL), Hodgkin-Reed Sternberg cell antigen presentation is intact, with viral expression restricted to sub-dominant latent-antigens including LMP1/2A. Large epidemiological studies have reported differential HLA-class I (HLA-I) susceptibility to EBV+ cHL. The functional basis for these observations is unknown. HLA-I molecules present viral peptides for recognition by CD8+ T-cells, and it may be that the relative risk of developing EBV+ cHL is due to HLA-I alleles influencing the magnitude of CD8+ T-cell immunity against relevant EBV-specific antigens. However this remains speculative, with immunological evidence lacking. Several non-HLA-I linked genetic susceptibility loci have been identified, and HLA-I associations may simply represent markers for genes of diverse functions that are in linkage disequilibrium to the HLA-I region. We undertook an Australasian Leukaemia and Lymphoma Group study to address this fundamental question, utilizing 4 distinct but complimentary experimental approaches. 1. 9 EBV+ cHL and 11 EBV-ve cHL pre-therapy PBMC samples were tested for ex-vivo IFNγ, TNFα and CD107a CD8+ T-cell immunity, using overlapping LMP1 and LMP2A peptide pools. The non-HRS expressed EBV-lytic protein BZLF1 was a control. Highly stringent FACS gating was used to maximize specificity. Results were interrogated using Profile and SPICE analysis. Interestingly IFNγ, TNFα and CD107 CD8+ T-cell responses in HLA-A*02 EBV+ cHL (but not EBV-ve cHL) patients were greater than non-HLA-A*02 (LMP1 p=0.002; LMP2A p=0.03; combined LMP1/LMP2A p=0.005), whereas BZLF1 was equivalent, indicating that HLA-I provides differential CD8+ T-cell immunity against relevant EBV-latent antigens in EBV+ cHL but not EBV-ve cHL. 2. However, up to 4 different HLA-A/B molecules can potentially present relevant EBV-derived epitopes in each individual, adding a confounding layer of complexity to single allele-based effects. To overcome this and enhance sensitivity, we used the mutant HLA-I 721.221 cell-line (pulsed with LMP2A), transfected with either HLA-A*01, HLA-A*02, HLA-A*03 or HLA-B*08 alleles, as antigen presenting cells to in-vitro expand LMP2A-specific CD8+ T-cells from HLA-A*02 heterozygotes. This found ∼90% of the HLA-I LMP2A response was restricted through HLA-A*02. 3. In contrast to EBV+ cHL, in EBV-post-transplant lymphoproliferative disorders (EBV+ PTLD) the immunogenic EBNA3A/3B/3C latent-antigens are expressed. We compared HLA-I associations in 110 cHL (35% EBV+ cHL) to 153 PTLD (63% EBV+ PTLD) patients. Using Bonferoni corrected statistics, we confirmed that HLA-A*02 and HLA-A*01 homozygotes had lower and higher susceptibility to EBV+ cHL respectively, and that HLA-B*37 was positively associated. Notably, no HLA-I associations with EBV+ PTLD were found. 4. To investigate the impact of HLA-I on the hierarchy of CD8+ T-cell immunity to sub-dominant (LMP1/2A) and immune-dominant (EBNA3A/3B/3C) EBV-latent proteins, we analysed the diversity of HLA-class I restricted T-cells in 30 healthy EBV+ participants. To supplement 30 ‘defined' (i.e. validated) HLA-I EBV-latent antigen epitopes and expand HLA-I coverage, we identified 31 ‘SYFPEITHI' bioinformatically ‘predicted' peptide epitopes for HLA-A*01, HLA-A*03 or HLA-B*37 restricted EBV-latent antigens. All SYFPEITHI scores were ≥21, and thermal stability circular dichroism analysis (HLA-A*01) or MHC stabilization assays on T2 cells (HLA-A*03) confirmed peptide binding to HLA-I. Ex-vivo CD107 CD8+ T-cell assays for the 61 peptides, found that sub-dominant LMP1/2A-specific peptide responses were largely confined to HLA-A*02 (Fig 1A), whilst immuno-dominant CD8+ T-cell responses were stimulated by peptides presented by numerous HLA-I alleles (Fig 1B). These data combined illustrate that differential HLA-I-associated susceptibility to EBV+ cHL reflects altered EBV latent antigen-specific CD8+ T-cell immune hierarchies. For lymphomas expressing a restricted set of poorly immunogenic proteins, even modest CD8+ T-cell responses against relevant tumor-associated proteins confer protection, with broad implications for EBV-vaccine design. Studies are required to determine if similar mechanisms are applicable to non-lymphoid EBV+ malignancies with restricted latency such as undifferentiated nasopharngeal carcinoma. Disclosures: No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document