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In vitro expanded and activated polyclonal γδ memory T cells for treatment of cancer

ABSTRACT: γδ-T lymphocytes are cells of the innate immune system exerting potent natural cytotoxicity against bacteria, viruses and tumours. This ability, coupled with their negligible alloreactivity, makes them attractive for adoptive immunotherapy approaches. To achieve a cell product suitable for clinical use, a protocol offering the possibility to generate and expand high numbers of polyclonal γδ-T cells is required. In this study, we designed a robust protocol to either manually or automatically expand high numbers of functional polyclonal memory γδ-T cells under good manufacturing practice conditions, with the additional possibility of gene-modification to improve anti-tumour activity, proving the feasibility of establishing an allogeneic “third-party T-cell bank” for off-the-shelf use. Engineered artificial antigen-presenting cells (aAPCs) expressing CD86/41BBL/CD40L and the cytomegalovirus (CMV)-antigen-pp65 were used for γδ-T cell production. The presence of CMV-pp65 and CD40L proved to be crucial for expansion of the memory Vδ1 subpopulation. To allow clinical translation and guarantee patient safety, aAPCs were stably transduced with an inducible suicide gene. The proposed cell product represents an attractive therapeutic option endowed with broad clinical applications, including treatment of viral infections in highly immunocompromised patients, treatment of aggressive malignancies refractory to conventional approaches and, ultimately, innovative platform for development of off-the-shelf CAR-T-cell products.

INSTRUMENT(S): Orbitrap Fusion ETD

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): T Cell, Blood

SUBMITTER: Andrea Petretto

LAB HEAD: Andrea Petretto

PROVIDER: PXD015506 | Pride | 2019-11-18

REPOSITORIES: Pride

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Project description:Reconstitution of cytomegalovirus (CMV)-specific immunity following transplant remains a primary clinical objective to prevent CMV disease, and adoptive immunotherapy of CMV-specific T cells can be an effective therapeutic approach. Due to the persistence of CMV, most CMV-specific CD8+ T cells become terminally differentiated effector cells (TEFF). However, a minor subset retains a memory phenotype (TM). Interestingly, recent studies suggest that CMV-specific CD8+ T cells with different phenotypes may have different abilities to reconstitute sustained immunity following transfer. The immunology of human CMV (HCMV) infections is reflected in the mouse model of MCMV infection. We found that HCMV- and MCMV-specific T cells displayed shared genetic programs, validating the MCMV model for studies of CMV-specific T cells in vivo. After transfer, the proliferative capacity of MCMV-specific TM cells was vastly superior to TEFF cells. Strikingly, TM cells expanded and established sustained and diverse T cell populations even after multiple challenges. Although both TEFF and TM cells could protect Rag-/- mice, only TM cells could consistently survive after transfer into immune replete, latently infected recipients and respond if recipient immunity was lost. These data show that CMV-specific TM cells retain memory function during persistent infection and can re-establish CMV immunity when necessary. C57BL/6 mice were infected intraperitoneally (i.p.) with MCMV strain MW97.01 between 6-16 weeks of age. Splenocytes were isolated from chronically-infected mice and co-stained with three PE-conjugated tetramers loaded with the antigenic peptides from M38, m139 and IE3, all of which promote memory inflation. Cells were then stained with fluorescently conjugated antibodies and sorted on a MoFlo cell sorter. Naïve CD8+ cells were identified as CD44lo. MCMV-specific T cells were identified as CD8+, CD44hi and tetramer binding and then further segregated into memory and effector cells subsets by their expression of KLRG1 and CD127.

Project description:The avidity of the T-cell receptor (TCR) for antigenic peptides presented by the MHC (pMHC) on cells is an essential parameter for efficient T cell-mediated immunity. Yet, whether the TCR-ligand avidity can drive the clonal evolution of virus antigen-specific CD8 T cells, and how this process is determined in latent Cytomegalovirus (CMV)- against Epstein-Barr virus (EBV)-mediated infection remains largely unknown. Here, we quantified monomeric TCR-pMHC dissociation rates on CMV- and EBV-specific individual TCR-alpha-beta clonotypes and polyclonal CD8 T cell populations in healthy donors over a follow-up time of 15-18 years. Within CMV/pp65-specific T cell repertoires, a progressive contraction of clonotypes with high TCR-pMHC avidity and low CD8 binding dependency was observed, leading to an overall avidity decline during long-term antigen exposure. We identified a unique transcriptional signature preferentially expressed by high-avidity CMV/pp65-specific T cell clonotypes, including the inhibitory receptor LILRB1. Interestingly, T cell clonotypes of high-avidity showed higher LILRB1 expression than the low-avidity ones and LILRB1 blockade moderately increased T cell proliferation. Similar findings were made for CD8 T cell repertoires specific for the CMV/IE-1 epitope. There was a gradual in vivo loss of high-avidity T cells with time for both CMV specificities, corresponding to virus-specific CD8 T cells expressing enhanced LILRB1 levels. In sharp contrast, the EBV/BMFL1-specific T cell clonal composition and distribution, once established, displayed an exceptional stability, unrelated to TCR-pMHC binding avidity or LILRB1 expression. Together, these findings reveal an overall long-term avidity decline of CMV- but not EBV-specific T cell clonal repertoires, highlighting the differing role played by TCR-ligand avidity over the course of these two latent herpesvirus infections. Our data suggest that the inhibitor receptor LILRB1 potentially restricts the clonal expansion of high-avidity CMV-specific T cell clonotypes during latent infection. We propose that the mechanisms regulating the long-term outcome of CMV- and EBV-specific memory CD8 T cell clonotypes in humans are distinct.

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In vitro expanded and activated polyclonal γδ memory T cells for treatment of cancer

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