scholarly journals 739 Intratumor childhood vaccine-specific CD4+ T cell recall helps antitumor CD8 T cells

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A770-A770
Author(s):  
Michael Brown ◽  
Zachary McKay ◽  
Yuanfan Yang ◽  
Darell Bigner ◽  
Smita Nair ◽  
...  

BackgroundPVSRIPO, a recombinant poliovirus derived from the live-attenuated Sabin oral polio vaccine strain, is being tested in multi-institutional phase II clinical trials for recurrent glioblastoma (NCT04479241) and unresectable, PD-1 refractory melanoma (NCT04577807) in combination with PD1 blockade. PVSRIPO capsid is identical to the Sabin vaccine strain and >99% identical to the inactivated Polio vaccine (IPOL, Salk), against which public health mandated childhood vaccination is near universal. In non-vaccinated mice, PVSRIPO mediates antitumor efficacy in a replication-dependent manner via engaging innate inflammation and antitumor T cells. Accordingly, it is anticipated that pre-existing immunity to PVSRIPO impedes antitumor therapy. However, recent evidence indicates that immunological 'recall', or reactivation of memory T cells, may mediate anti-tumor effects.MethodsThe impact of prior polio vs control (KLH) vaccination on intratumor viral replication, tumor inflammation, and overall tumor growth after intratumor PVSRIPO therapy was assessed in murine tumor models. The role of polio capsid and tetanus recall antigens in mediating intratumor inflammation and antitumor efficacy was similarly studied in mice non-permissive to PVSRIPO infection. To mechanistically define antitumor effects of polio recall, B cell and CD8 T cell knockout mice were used, in addition to adoptive transfer of CD4+ T cells from vaccinated mice. Intratumor polio or tetanus recall antigen therapy was performed after OT-I transfer (OVA-specific T cells) in the B16-OVA melanoma model to gauge antitumor T cell activity. Lastly, the inflammatory effects of polio and tetanus antigens was tested in human peripheral blood mononuclear cells (PBMCs).ResultsDespite curtailing intratumor viral replication, prior polio vaccination in mice potentiated subsequent antitumor efficacy of PVSRIPO. Intratumor recall responses induced by polio and tetanus antigens also delayed tumor growth. Recall antigen therapy was associated with marked intratumor influx of eosinophils, conventional CD4+ T cells, and increased expression of IFN-g, TNF, and Granzyme B in tumor infiltrating T cells. The antitumor efficacy of polio recall antigen was mediated by CD4+ T cells, partially depended upon CD8+ T cells, and was impaired by B cells. Both polio and tetanus recall antigen therapy bolstered the antitumor function of tumor-specific OT-I CD8+ T cells. Polio and tetanus antigens induced CXCL10 and type I/II/III IFNs in PBMCs in vitro.ConclusionsChildhood vaccine-specific CD4+ T cells hold cancer immunotherapy potential. In the context of PVSRIPO therapy, antitumor and inflammatory effects of polio vaccine-specific CD4+ T cell recall supersedes inhibitory effects of attenuated intratumor viral replication, and represents a novel mechanism of action.Ethics ApprovalThe animal work described in this study was approved by the Duke University IACUC.

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Stephanie M. Dillon ◽  
Tezha A. Thompson ◽  
Allison J. Christians ◽  
Martin D. McCarter ◽  
Cara C. Wilson

Abstract Background The etiology of the low-level chronic inflammatory state associated with aging is likely multifactorial, but a number of animal and human studies have implicated a functional decline of the gastrointestinal immune system as a potential driver. Gut tissue-resident memory T cells play critical roles in mediating protective immunity and in maintaining gut homeostasis, yet few studies have investigated the effect of aging on human gut T cell immunity. To determine if aging impacted CD4 T cell immunity in the human large intestine, we utilized multi-color flow cytometry to measure colonic lamina propria (LP) CD4 T cell frequencies and immune-modulatory marker expression in younger (mean ± SEM: 38 ± 1.5 yrs) and older (77 ± 1.6 yrs) adults. To determine cellular specificity, we evaluated colon LP CD8 T cell frequency and phenotype in the same donors. To probe tissue specificity, we evaluated the same panel of markers in peripheral blood (PB) CD4 T cells in a separate cohort of similarly aged persons. Results Frequencies of colonic CD4 T cells as a fraction of total LP mononuclear cells were higher in older persons whereas absolute numbers of colonic LP CD4 T cells per gram of tissue were similar in both age groups. LP CD4 T cells from older versus younger persons exhibited reduced CTLA-4, PD-1 and Ki67 expression. Levels of Bcl-2, CD57, CD25 and percentages of activated CD38+HLA-DR+ CD4 T cells were similar in both age groups. In memory PB CD4 T cells, older age was only associated with increased CD57 expression. Significant age effects for LP CD8 T cells were only observed for CTLA-4 expression, with lower levels of expression observed on cells from older adults. Conclusions Greater age was associated with reduced expression of the co-inhibitory receptors CTLA-4 and PD-1 on LP CD4 T cells. Colonic LP CD8 T cells from older persons also displayed reduced CTLA-4 expression. These age-associated profiles were not observed in older PB memory CD4 T cells. The decline in co-inhibitory receptor expression on colonic LP T cells may contribute to local and systemic inflammation via a reduced ability to limit ongoing T cell responses to enteric microbial challenge.


2020 ◽  
Vol 117 (32) ◽  
pp. 19408-19414 ◽  
Author(s):  
Michael P. Crawford ◽  
Sushmita Sinha ◽  
Pranav S. Renavikar ◽  
Nicholas Borcherding ◽  
Nitin J. Karandikar

Untoward effector CD4+ T cell responses are kept in check by immune regulatory mechanisms mediated by CD4+ and CD8+ T cells. CD4+ T helper 17 (Th17) cells, characterized by IL-17 production, play important roles in the pathogenesis of autoimmune diseases (such as arthritis, multiple sclerosis, psoriasis, inflammatory bowel disease, among others) and in the host response to infection and cancer. Here, we demonstrate that human CD4+ T cells cells exposed to a Th17-differentiating milieu are significantly more resistant to immune suppression by CD8+ T cells compared to control Th0 cells. This resistance is mediated, in part, through the action of IL-17A, IL-17F, and IL-17AF heterodimer through their receptors (IL-17RA and IL-17RC) on CD4+ T cells themselves, but not through their action on CD8+ T cells or APC. We further show that IL-17 can directly act on non-Th17 effector CD4+ T cells to induce suppressive resistance, and this resistance can be reversed by blockade of IL-1β, IL-6, or STAT3. These studies reveal a role for IL-17 cytokines in mediating CD4-intrinsic immune resistance. The pathways induced in this process may serve as a critical target for future investigation and immunotherapeutic intervention.


2020 ◽  
Vol 5 (51) ◽  
pp. eabb5590 ◽  
Author(s):  
Heather M. Ren ◽  
Elizabeth M. Kolawole ◽  
Mingqiang Ren ◽  
Ge Jin ◽  
Colleen S. Netherby-Winslow ◽  
...  

Development of tissue-resident memory (TRM) CD8 T cells depends on CD4 T cells. In polyomavirus central nervous system infection, brain CXCR5hi PD-1hi CD4 T cells produce interleukin-21 (IL-21), and CD8 T cells lacking IL-21 receptors (IL21R−/−) fail to become bTRM. IL-21+ CD4 T cells exhibit elevated T cell receptor (TCR) affinity and higher TCR density. IL21R−/− brain CD8 T cells do not express CD103, depend on vascular CD8 T cells for maintenance, are antigen recall defective, and lack TRM core signature genes. CD4 T cell–deficient and IL21R−/− brain CD8 T cells show similar deficiencies in expression of genes for oxidative metabolism, and intrathecal delivery of IL-21 to CD4 T cell–depleted mice restores expression of electron transport genes in CD8 T cells to wild-type levels. Thus, high-affinity CXCR5hi PD-1hi CD4 T cells in the brain produce IL-21, which drives CD8 bTRM differentiation in response to a persistent viral infection.


Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3175-3175
Author(s):  
Sanju Jalla ◽  
Erin McCadden ◽  
Jie Wang ◽  
Ephraim J. Fuchs ◽  
Katharine A. Whartenby

Abstract Since CD4+ T cell help has been proposed to be required for maintaining the activity of tumor-specific CD8+ T cells, tolerance in tumor-specific CD4+ T cells may seriously impair the efficacy of therapeutic tumor vaccines. To overcome this problem, we devised a strategy to “engineer” CD4+ T cell help by treating tumor-bearing animals with nonmyeloablative conditioning and transplantation of autologous hematopoietic stem cells (HSCs) that have been genetically modified, via lentiviral transduction, to express an antigen containing “foreign” CD4+ T cell epitopes. After hematopoietic reconstitution, animals received the combination of an autologous tumor cell vaccine and an infusion of primed CD4+ T cells specific for the expressed epitopes. Using influenza hemagglutinin (HA) as the model antigen, we first confirmed that transplantation of HA-transduced HSCs led to efficient expression of HA by antigen-presenting cells, as demonstrated by the clonal expansion of adoptively transferred, HA-specific CD4+ transgenic T cells in mice receiving HA-transduced HSCs but not in mice receiving nerve growth factor receptor (NGFR) gene-transduced HSCs. Next, BALB/c mice harboring 13 day old, metastatic 4T1 mammary cancer were treated with removal of the primary, nonmyeloablative conditioning and transplantation of HA-transduced syngeneic HSCs, and following hematopoietic reconstitution, with concomitant autologous tumor cell vaccination and adoptive transfer of in vitro activated, HA-specific transgenic CD4+ T cells. This therapy was successful in curing the majority of tumor bearing mice, and was superior to the same therapy given to mice transplanted with NGFR-transduced stem cells. Finally, we found that the anti-tumor effect of vaccination plus exogenous T cell help was abolished by the adoptive transfer of either CD4+ or CD8+ T cells from tumor-bearing mice, suggesting that tumor-bearing mice contain both potential effectors and suppressors of anti-tumor immunity, the latter of which are abolished by the non-myeloablative conditioning. These results highlight the importance of CD4+ T cell help in the induction of therapeutic anti-tumor immunity.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3255-3255
Author(s):  
Nicholas Leigh ◽  
Guanglin Bian ◽  
Wei Du ◽  
George L. Chen ◽  
Hong Liu ◽  
...  

Abstract Graft versus tumor (GVT) effect is the desired and integral outcome for successful allogeneic bone marrow transplantation (allo-BMT) for cancer patients. This effect is dependent on T cell mediated recognition and elimination of residual host tumor cells present after allo-BMT. T cell killing is mediated primarily via three pathways: perforin/granzymes, Fas/FasL, and cytotoxic cytokines. Recent work from our lab has revealed a detrimental role for granzyme B (GzmB) in GVT effect due to its role in activation induced cell death (AICD) of CD8+ T cells. As a result, GzmB-/- CD8+ T cells exhibited higher expansion after allo-BMT and subsequently provided better tumor control. Our current study sought to determine the role of perforin (Prf1) in GVT effect mediated by both CD4+ and CD8+ T cells. Using the MHC-mismatched C57BL/6 (H-2b) to BALB/c (H-2d) allo-BMT model, we first confirmed previous findings that when transplanting CD8+ T cells along with T cell depleted (TCD) BM cells, donor CD8+ T cells require Prf1 to mediate GVT effect against allogeneic A20 lymphoma (Fig 1A, Prf1-/- (n=4) vs WT (n=4), *P<0.05). In addition, our data suggest that Prf1 is also required for CD4+ T cells to effectively mediate GVT effect against A20, as transplant with Prf1-/- CD4+CD25- T cells does not control tumor growth as well as WT controls (Fig 1B). Our previous work showed that GzmB deficiency allows for less AICD and subsequently more CD8+ T cell expansion. New data now show a similar effect for Prf1 in CD8+ T cell accumulation, as Prf1-/- CD8+ T cells outcompete WT CD8+ T cells (CD45.1+) when these two genotypes are mixed in equal numbers and transplanted into tumor bearing BALB/c mice (n=5/time point, *P=0.02 day 9)(Fig 1C). This competitive advantage was due to less AICD in the Prf1-/- CD8+ T cells. However, Prf1 appears to be required for efficient GVT activity, because the higher number of Prf1-/- CD8+ T cells are still less capable than WT counterparts in controlling tumor growth. We next tested the effect of Prf1 in AICD in CD4+CD25- T cells, and again co-transplanted WT CD45.1+ and Prf1-/- CD4+CD25- T cells into tumor bearing mice for a competition assay. Unexpectedly, WT CD4+CD25- T cells accumulate to significantly higher numbers when in direct competition with Prf1-/- CD4+CD25- T cells (n=4/time point, **,P<0.01)(Fig 1D). When we measured apoptotic cells with Annexin V staining, we found that WT CD4+CD25- T cells still had significantly more AICD (Prf1-/- 38.3 ± 4.2% vs. WT 48.1 ± 5.1%, P<0.01 on day 7 post-BMT; Prf1-/- 12.7 ± 1.0% vs. WT 18.1 ± 3.4%, P<0.03 on day 9 post-BMT). This result suggests that while Prf1 has an important role in AICD, it may also play a role in another feature of CD4+ T cell biology. We then explored the hypothesis that may Prf1 promote CD4+ T cell proliferation by evaluating Hoescht staining on day 9 post-BMT. Preliminary results suggest that Prf1 may enhance T cell proliferation, as Prf1-/- CD4+ T cells have less actively dividing cells at this time point. Therefore, Prf1 appears to have a surprising role after allo-BMT in sustaining T cell expansion for CD4+ T cells, but not for CD8+ T cells. Another factor influencing GVT effect may be T cell phenotype. Our previous work with CD8+ T cells suggests that more effector memory (CD62LLOWCD44HIGH) T cells accumulate in the absence of GzmB, and that GzmB-/- CD8+ T cells exhibited higher GVT activity than WT controls. We now found that while Prf1-/- CD4+ T cells also skewed towards the effector memory phenotype (CD62LLOWCD44HIGH), loss of Prf1 still reduced the ability of CD4+ T cells to control tumor growth in this model of allo-BMT. In summary, our results suggest that Prf1 plays an important role in GVT responses mediated not only by CD8+ T cells but also by CD4+ T cells, which were shown in previous literature to mainly utilize Fas ligand and cytokine systems to mediate GVT activity. In addition, Prf1 can cause AICD to both CD4+ and CD8+ T cells after allo-BMT. While Prf1-induced AICD reduces CD8+ T cell expansion, Prf1 appears to play a previously unrecognized role enhancing CD4+ T cell proliferation via an unidentified mechanism. Disclosures: No relevant conflicts of interest to declare.


2006 ◽  
Vol 74 (10) ◽  
pp. 5790-5801 ◽  
Author(s):  
Sonja Lütjen ◽  
Sabine Soltek ◽  
Simona Virna ◽  
Martina Deckert ◽  
Dirk Schlüter

ABSTRACT Toxoplasma gondii induces a persistent central nervous system infection, which may be lethally reactivated in AIDS patients with low CD4 T-cell numbers. To analyze the role of CD4 T cells for the regulation of parasite-specific CD8 T cells, mice were infected with transgenic T. gondii expressing the CD8 T-cell antigen β-galactosidase (β-Gal). Depletion of CD4 T cells prior to infection did not affect frequencies of β-Gal876-884-specific (consisting of residues 876 to 884 of β-Gal) CD8 T cells but resulted in a pronounced reduction of intracerebral β-Gal-specific gamma interferon (IFN-γ)-producing and cytolytic CD8 T cells. After cessation of anti-CD4 treatment a normal T. gondii-specific CD4 T-cell response developed, but IFN-γ production of intracerebral β-Gal-specific CD8 T cells remained impaired. The important supportive role of CD4 T cells for the optimal functional activity of intracerebral CD8 T cells was also observed in mice that had been depleted of CD4 T cells during chronic toxoplasmosis. Reinfection of chronically infected mice that had been depleted of CD4 T cells during either the acute or chronic stage of infection resulted in an enhanced proliferation of β-Gal-specific IFN-γ-producing splenic CD8 T cells. However, reinfection of chronically infected mice that had been depleted of CD4 T cells in the acute stage of infection did not reverse the impaired IFN-γ production of intracerebral CD8 T cells. Collectively, these findings illustrate that CD4 T cells are not required for the induction and maintenance of parasite-specific CD8 T cells but, depending on the stage of infection, the infected organ and parasite challenge infection regulate the functional activity of intracerebral CD8 T cells.


2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Kunlong Xiong ◽  
Jinxia Niu ◽  
Ruijuan Zheng ◽  
Zhonghua Liu ◽  
Yanzheng Song ◽  
...  

β-Catenin is a key molecule of canonical Wnt/β-catenin pathway. Its roles and expression profiles in T cells of tuberculosis (TB) remain unclear. The aim of this study was to explore the role of β-catenin in CD4+ T cells and its expression characteristics in patients with pulmonary tuberculosis (PTB). In this study, CD4+ T cell-specific β-catenin conditional knockout mice (β-CAT-cKO mice) were aerosol infected with Mycobacteria tuberculosis (Mtb) H37RV with wild-type mice as controls. Four weeks after infection, the mRNA expression of IFN-γ, TNF-α, and TCF-7 in the lungs of mice was measured. CD4, CD8, β-catenin, IFN-γ, and TNF-α in mononuclear cells from the lungs and spleens were measured by flow cytometry, and the pathological changes of lungs were also observed. Patients with PTB were enrolled, with blood samples collected and PBMCs isolated. The expressions of β-catenin, IFN-γ, TNF-α, and PD-1 in CD4+ and CD8+ T cells were measured by flow cytometry. Results showed a decreased frequency of and reduced IFN-γ/TNF-α mRNA expression and secretion by CD4+ T cells in the lungs of infected β-CAT-cKO mice compared with infected wild-type controls, and only slightly more inflammatory changes were observed in the lungs. β-catenin expressions in CD4+ and CD8+ T cells were significantly decreased in blood cells of patients with severe PTB compared with those in mild PTB. The stimulation of peripheral blood mononuclear cells (PBMCs) with lithium chloride (LiCl), a stimulant of β-catenin, resulted in the increase in CD4+ T cell frequency, as well as their secretion of IFN-γ and TNF-α. β-Catenin demonstrated a moderately positive correlation with PD-1 in CD4+ T cells. β-Catenin along with PD-1 and IFN-γ in CD4+ T cells had a high correlation with those in CD8+ T cells. In conclusion, β-catenin may be involved in the regulation of Th1 response and CD4+ T cell frequency in TB.


Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3063-3063
Author(s):  
Sanju Jalla ◽  
Jie Wang ◽  
Leo Luznik ◽  
Ephraim J. Fuchs

Abstract Recent evidence suggests that tumor-bearing animals contain CD8+ T cells that can respond productively to a tumor vaccine, but that these T cells do not respond because of insufficient help from tumor-specific CD4+ T cells, which have either been inactivated or turned into anti-tumor suppressor T cells. We therefore devised a strategy to augment anti-tumor immunity by administering cyclophosphamide (Cy), to eliminate suppressor CD4+ T cells, followed by combining autologous tumor cell vaccination and infusion of partially MHC-mismatched, or haploidentical, CD4+ T cells as a source of T cell help for endogenous CD8+ T cells. Interestingly, the combination of Cy followed by haploidentical T cell infusion, with or without vaccine, induced potent systemic anti-tumor immunity resulting in cure of 40-50% of BALB/c mice harboring the A20 B cell leukemia/lymphoma. Depletion of CD8+ T cells from the infusate abrogated GVHD but did not compromise anti-tumor immunity. Allogeneic donor spleen cells that contained CD8+ T cells engrafted durably and caused lethal GVHD. In contrast, the combination of Cy plus CD8+ T cell-depleted spleen cell infusion induced only transient engraftment, peaking on day 7 and declining to undetectable levels by day 14. In the absence of Cy conditioning, allogeneic donor spleen cell infusions did not induce detectable chimerism beyond day 3. In summary, Cy plus allogeneic CD4+ T cell infusion induces potent anti-tumor immunity in a mouse model of B cell leukemia/lymphoma. Potential mechanisms of the therapeutic effect include direct tumor cytotoxicity by CD4+ T cells or allogeneic CD4+ T cell help for endogenous, tumor-specific CD8+ T cells.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3160-3160
Author(s):  
William J. Murphy ◽  
Lisbeth A. Welniak ◽  
Minghui Li ◽  
Thomas J. Sayers ◽  
Angela Panoskaltsis-Mortari ◽  
...  

Abstract Proteasome inhibition is an innovative and promising approach for treating hematologic malignancies and may provide immunomodulatory effects. We have shown that systemic proteasome inhibition using bortezomib administered immediately following bone marrow transplantation (BMT) resulted in marked inhibition of acute graft-versus-host disease (GVHD) with retention of graft-versus-tumor (GVT) effects in mice. Surprisingly, extended administration of bortezomib exacerbated GVHD-dependent mortality due to severe gut toxicity (Sun, et al. Blood, 106:3293–9, 2005). This suggested that a narrow therapeutic index for bortezomib administration may limit its application for prevention of tumor relapse in the patients who had previously undergone allogeneic BMT. In this study, we have extended the investigation to determine the relative importance of CD4+ and CD8+ T cells in the development of this GVHD-dependent gut toxicity as well as potentially increase GVT induced by extended bortezomib treatment. Using two MHC-mismatched BMT models, C57BL/6 or BALB/c recipients of a defined dose of CD4+ T cell-depleted allogeneic donor splenocytes had significantly reduced GVHD-dependent toxicity from prolonged bortezomib treatment (7.5–15 ug/dose given every 4–6 days beginning on the day of transplant for a total of 4–5 injections). No protection from toxicity was seen with donor CD8+ T cell depletion. Decreased bortezomib related gut toxicity was also seen with in vivo CD4+ T cell depletion after allogeneic BMT. Interestingly, depletion of the donor CD4+ T cells resulted in reduced serum TNF-αlevels correlating with the decreased bortezomib-induced toxicity. However, the recipients receiving prolonged bortezomib had high levels of serum IFN-γ produced by the remaining donor CD8+ T cells despite the absence of GVHD lethality. To confirm the role of CD4+ T cells in mediating the toxicity associated with prolonged bortezomib administration a multiple minor histocompatibility antigen mismatch model was used in which CD8+ T cells are the primary effector in GVHD. C3.SW donor splenocytes and BM were transferred into irradiated C57BL/6 recipients. Prolonged administration of bortezomib resulted in significantly lower GVHD-dependent toxicity in this strain combination confirming the importance of CD4+ T cells in mediating the GVHD-dependent toxicity. We then addressed the effects of continuous bortezomib administration on GVT responses. We used two different MHC-mismatch BMT models with recipients bearing either A20 lymphoma (H2d) or C1498 leukemia (H2b). Tumor-bearing mice receiving an allogeneic BMT with a defined dose of CD4+ T cell-depleted donor splenocytes below the normal threshold required for GVHD/GVT and prolonged bortezomib administration resulted in marked GVT responses. These observations suggest that bortezomib induced GVHD-dependent gut toxicity and increased GVT activity associated with prolonged administration can at least be partially separated by modulation of donor T cell subsets, particularly CD4+ T cells, in the donor graft. Thus prolonged administration of bortezomib together with CD8+ T cell mediated GVT results in synergistic augmentation of anti-tumor activity compared to either modality alone.


Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2225-2225
Author(s):  
Maarten L. Zandvliet ◽  
J.H. Frederik Falkenburg ◽  
Louise A. Veltrop-Duits ◽  
Marco W. Schilham ◽  
Roelof Willemze ◽  
...  

Abstract Human Adenovirus (HAdV) can cause serious morbidity in immunocompromised patients, in particular in pediatric recipients of allogeneic stem cell transplantation (alloSCT). Progression to disseminated adenoviral disease is associated with a high mortality, despite treatment with antiviral agents such as ribavirin and cidofovir. It has been demonstrated that reconstitution of HAdV-specific T cells is essential to control adenoviral infection after alloSCT. Adoptive transfer of donor-derived HAdV-specific T cells may therefore be a strategy to provide long-term protection from HAdV. In healthy individuals, T cells directed against HAdV are only detected at low frequencies and are predominantly directed to the HAdV hexon protein. Only recently, a number of immunodominant CD8+ and CD4+ epitopes of HAdV hexon have been defined. Since these epitopes are largely conserved between the different HAdV subgroups, T cells specific for these immunodominant epitopes may provide protection from a wide range of adenoviral serotypes. The aim of this study was to develop a method for the generation of combined CD8+ and CD4+ T cell lines with high and well defined specificity for the HAdV hexon protein. We first analyzed the frequencies of HAdV hexon-specific CD8+ and CD4+ T cells in healthy individuals using sensitive measurement by peptide-MHC tetramers, and intracellular cytokine staining combined with CD154 or peptide-MHC tetramer staining, after stimulation with defined MHC class I peptides, 30-mer peptides containing class II epitopes, or a HAdV hexon protein-spanning pool of overlapping 15-mer peptides (Miltenyi Biotec, Germany). We demonstrated that the frequencies of HAdV hexon-specific T cells were very low in most healthy individuals tested. HAdV hexon-specific CD8+ T cells were detectable in only 3/15 individuals (range 0.16–0.43% of CD8+ T cells), and hexon-specific CD4+ T cells were detected in all individuals with a median of 0.07% (range 0.004–0.38% of CD4+ T cells). The highest frequencies were found after stimulation with the hexon protein-spanning 15-mer peptide pool, indicating activation of both known and unknown epitopes. Kinetic analysis showed highest levels of IFNg production after 4–8 hours of stimulation for HAdV-specific CD8+ T cells, and after 4–48 hours of stimulation for HAdV-specific CD4+ T cells. The phenotype of these HAdV hexon-specific T cells corresponded to an early memory phenotype, CD27+, CD28+, CD62L+, CD45RO+. Despite these low or undetectable frequencies of HAdV-specific T cells, IFNg-based enrichment 4 hours after activation with the HAdV hexon protein-spanning peptide pool resulted in efficient isolation of CD8+ and CD4+ T cells recognizing both known and unknown HAdV hexon epitopes. Following a short culture period of 7 days, the T cell lines consisted of 49–80% CD8+ T cells and 13–15% CD4+ T cells. Restimulation by autologous EBV-LCL loaded with HAdV hexon peptide pool followed by intracellular IFNg staining showed that the frequency of HAdV-specific T cells was increased to 65–95% of CD8+ T cells, and 38–72% of CD4+ T cells. The frequency of HAdV-tetramer-positive cells was increased to 32–76% of CD8+ T cells, indicating that part of HAdV-specific CD8+ T cells recognized known epitopes. After 14 days, the frequency of HAdV-specific T cells had further increased to 89–94% of CD8+ T cells and 61–91% of CD4+ T cells. Starting with only 25x106 donor peripheral blood mononuclear cells, this strategy yielded T cell lines containing 1.3–2.7x106 HAdV-specific combined CD8+ and CD4+ T cells in 14 days. We conclude that we developed a GMP-grade method for the fast generation of highly HAdV-specific CD8+ and CD4+ T cell lines from all healthy donors tested, irrespective of HLA-restriction, for the treatment HAdV infection after alloSCT, with very limited risk of graft-versus-host disease.


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