scholarly journals αβ-T Cells Engineered to Express γδ-T Cell Receptors Can Kill Neuroblastoma Organoids Independent of MHC-I Expression

2021 ◽  
Vol 11 (9) ◽  
pp. 923
Author(s):  
Josephine G. M. Strijker ◽  
Ronja Pscheid ◽  
Esther Drent ◽  
Jessica J. F. van der Hoek ◽  
Bianca Koopmans ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Transcriptional Profiling ◽  
Γδ T Cells ◽  
Cell Receptor ◽  
Target Cells ◽  
Γδ T Cell ◽  
Mhc I ◽  
Organization Analysis ◽  
Αβ T Cells

Currently ~50% of patients with a diagnosis of high-risk neuroblastoma will not survive due to relapsing or refractory disease. Recent innovations in immunotherapy for solid tumors are highly promising, but the low MHC-I expression of neuroblastoma represents a major challenge for T cell-mediated immunotherapy. Here, we propose a novel T cell-based immunotherapy approach for neuroblastoma, based on the use of TEG002, αβ-T cells engineered to express a defined γδ-T cell receptor, which can recognize and kill target cells independent of MHC-I. In a co-culture killing assay, we showed that 3 out of 6 neuroblastoma organoids could activate TEG002 as measured by IFNγ production. Transcriptional profiling showed this effect correlates with an increased activity of processes involved in interferon signaling and extracellular matrix organization. Analysis of the dynamics of organoid killing by TEG002 over time confirmed that organoids which induced TEG002 activation were efficiently killed independent of their MHC-I expression. Of note, efficacy of TEG002 treatment was superior to donor-matched untransduced αβ-T cells or endogenous γδ-T cells. Our data suggest that TEG002 may be a promising novel treatment option for a subset of neuroblastoma patients.

scholarly journals P06.01 αβ-T cells engineered to express γδ-T cell receptors can kill neuroblastoma organoids independent of MHC-I expression

2021 ◽  
Vol 9 (Suppl 1) ◽  
pp. A19.1-A19
Author(s):  
JGM Strijker ◽  
E Drent ◽  
JJF van der Hoek ◽  
R Pscheid ◽  
B Koopmans ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Healthy Donor ◽  
Transcriptional Profiling ◽  
Cell Receptor ◽  
Γδ T Cell ◽  
Mhc I ◽  
Part Time ◽  
Αβ T Cells

BackgroundCurrently ~50% of patients with the diagnosis of high-risk neuroblastoma will not survive due to relapsing or refractory disease. Recent innovations in immunotherapy for solid tumors are highly promising, but the low MHC-I expression of neuroblastoma represents a major challenge for T cell-mediated immunotherapy. Here, we propose a novel T cell-based immunotherapy approach for neuroblastoma, based on the use of TEG002, αβ-T cells engineered to express a defined γδ-T cell receptor, which are thought to recognize and kill target cells independent of MHC-I. In this pilot project we have tested the potential efficacy of TEG002 therapy as a novel treatment for neuroblastoma, with tumor organoids.Materials and MethodsEffector cells were created from healthy donor peripheral blood T cells. The TEG002 cells were engineered by transducing αβ-T cells with a defined Vγ9Vδ2-T cell receptor. Both the untransduced αβ-T cells and the endogenous Vγ9Vδ2-T cells from the same healthy donor were used as controls in all experiments. Activation and killing of TEG002 was tested in a co-culture setting with neuroblastoma organoids. Supernatant of the co-culture was collected at 24 hours for IFNγ ELISA to measure activation of TEG002. The dynamics of cytotoxicity were analyzed over time from 0 till 72 hours, using the live-cell imaging system IncuCyte from Sartorius®. Killing was quantified using a Caspase3/7 Green dye and the IncuCyte software. Transcriptional profiling of the neuroblastoma organoids was done by RNA sequencing and MHC-I expression of the neuroblastoma organoids was determined by flow cytometry.ResultsWe showed that 3 out of 6 neuroblastoma organoids could activate TEG002 as measured by IFNγ production. Transcriptional profiling of the neuroblastoma organoids showed that this effect correlates with an increased activity of processes involved in interferon signaling and extracellular matrix organization. Analysis of the dynamics of organoid killing by TEG002 over time confirmed that organoids which induced TEG002 activation were efficiently killed independently of their MHC-I expression. Of note, efficacy of TEG002 treatment was superior to donor-matched untransduced αβ-T cells or endogenous γδ-T cells.ConclusionsWe demonstrated that 50% of tested neuroblastoma organoids can effectively activate TEG002 and that killing of the organoids is independent of MHC-I expression. Hence, this pilot study identified TEG002 as a promising novel cellular product for immunotherapy for a subset of neuroblastoma tumors, warranting further investigations into its clinical application.Disclosure InformationJ.G.M. Strijker: None. E. Drent: A. Employment (full or part-time); Significant; Gadeta BV. J.J.F. van der Hoek: None. R. Pscheid: A. Employment (full or part-time); Significant; Gadeta BV. B. Koopmans: None. K. Ober: None. S.R. van Hooff: None. W.M. Kholosy: None. C. Coomans: A. Employment (full or part-time); Significant; Gadeta BV. A. Bisso: A. Employment (full or part-time); Significant; Gadeta BV. M. van Loenen: A. Employment (full or part-time); Significant; Gadeta BV. J.J. Molenaar: None. J. Wienke: None.

scholarly journals Human γδ TCR Repertoires in Health and Disease

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 800 ◽  
Author(s):  
Alina Suzann Fichtner ◽  
Sarina Ravens ◽  
Immo Prinz
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Γδ T Cells ◽  
Cell Receptor ◽  
Γδ T Cell ◽  
Tcr Repertoire ◽  
Repertoire Diversity ◽  
Health And Disease ◽  
Αβ T Cells

The T cell receptor (TCR) repertoires of γδ T cells are very different to those of αβ T cells. While the theoretical TCR repertoire diversity of γδ T cells is estimated to exceed the diversity of αβ T cells by far, γδ T cells are still understood as more invariant T cells that only use a limited set of γδ TCRs. Most of our current knowledge of human γδ T cell receptor diversity builds on specific monoclonal antibodies that discriminate between the two major subsets, namely Vδ2+ and Vδ1+ T cells. Of those two subsets, Vδ2+ T cells seem to better fit into a role of innate T cells with semi-invariant TCR usage, as compared to an adaptive-like biology of some Vδ1+ subsets. Yet, this distinction into innate-like Vδ2+ and adaptive-like Vδ1+ γδ T cells does not quite recapitulate the full diversity of γδ T cell subsets, ligands and interaction modes. Here, we review how the recent introduction of high-throughput TCR repertoire sequencing has boosted our knowledge of γδ T cell repertoire diversity beyond Vδ2+ and Vδ1+ T cells. We discuss the current understanding of clonal composition and the dynamics of human γδ TCR repertoires in health and disease.

Recognition of the antigen-presenting molecule MR1 by a Vδ3+ γδ T cell receptor

2021 ◽  
Vol 118 (49) ◽  
pp. e2110288118
Author(s):  
Michael T. Rice ◽  
Anouk von Borstel ◽  
Priyanka Chevour ◽  
Wael Awad ◽  
Lauren J. Howson ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
Γδ T Cells ◽  
Cell Receptor ◽  
Γδ T Cell ◽  
Recognition Mechanism ◽  
Antigen Determination ◽  
Γδ T Cell Receptor ◽  
Αβ T Cells

Unlike conventional αβ T cells, γδ T cells typically recognize nonpeptide ligands independently of major histocompatibility complex (MHC) restriction. Accordingly, the γδ T cell receptor (TCR) can potentially recognize a wide array of ligands; however, few ligands have been described to date. While there is a growing appreciation of the molecular bases underpinning variable (V)δ1+ and Vδ2+ γδ TCR-mediated ligand recognition, the mode of Vδ3+ TCR ligand engagement is unknown. MHC class I–related protein, MR1, presents vitamin B metabolites to αβ T cells known as mucosal-associated invariant T cells, diverse MR1-restricted T cells, and a subset of human γδ T cells. Here, we identify Vδ1/2− γδ T cells in the blood and duodenal biopsy specimens of children that showed metabolite-independent binding of MR1 tetramers. Characterization of one Vδ3Vγ8 TCR clone showed MR1 reactivity was independent of the presented antigen. Determination of two Vδ3Vγ8 TCR-MR1-antigen complex structures revealed a recognition mechanism by the Vδ3 TCR chain that mediated specific contacts to the side of the MR1 antigen-binding groove, representing a previously uncharacterized MR1 docking topology. The binding of the Vδ3+ TCR to MR1 did not involve contacts with the presented antigen, providing a basis for understanding its inherent MR1 autoreactivity. We provide molecular insight into antigen-independent recognition of MR1 by a Vδ3+ γδ TCR that strengthens an emerging paradigm of antibody-like ligand engagement by γδ TCRs.

An obligate role for T-cell receptor αβ+ T cells but not T-cell receptor γδ+ T cells, B cells, or CD40/CD40L interactions in a mouse model of atopic dermatitis

2001 ◽  
Vol 107 (2) ◽  
pp. 359-366 ◽  
Author(s):  
Amy L. Woodward ◽  
Jonathan M. Spergel ◽  
Harri Alenius ◽  
Emiko Mizoguchi ◽  
Atul K. Bhan ◽  
...  
Keyword(s):  
T Cells ◽  
Atopic Dermatitis ◽  
T Cell ◽  
B Cells ◽  
Mouse Model ◽  
T Cell Receptor ◽  
Γδ T Cells ◽  
Cell Receptor ◽  
Αβ T Cells

scholarly journals Strategies to Improve the Antitumor Effect of γδ T Cell Immunotherapy for Clinical Application

2021 ◽  
Vol 22 (16) ◽  
pp. 8910
Author(s):  
Masatsugu Miyashita ◽  
Teruki Shimizu ◽  
Eishi Ashihara ◽  
Osamu Ukimura
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Checkpoint ◽  
Checkpoint Inhibitors ◽  
Γδ T Cells ◽  
Target Cells ◽  
Γδ T Cell ◽  
Antitumor Effects ◽  
Cell Immunotherapy ◽  
T Cell Immunotherapy

Human γδ T cells show potent cytotoxicity against various types of cancer cells in a major histocompatibility complex unrestricted manner. Phosphoantigens and nitrogen-containing bisphosphonates (N-bis) stimulate γδ T cells via interaction between the γδ T cell receptor (TCR) and butyrophilin subfamily 3 member A1 (BTN3A1) expressed on target cells. γδ T cell immunotherapy is classified as either in vivo or ex vivo according to the method of activation. Immunotherapy with activated γδ T cells is well tolerated; however, the clinical benefits are unsatisfactory. Therefore, the antitumor effects need to be increased. Administration of γδ T cells into local cavities might improve antitumor effects by increasing the effector-to-target cell ratio. Some anticancer and molecularly targeted agents increase the cytotoxicity of γδ T cells via mechanisms involving natural killer group 2 member D (NKG2D)-mediated recognition of target cells. Both the tumor microenvironment and cancer stem cells exert immunosuppressive effects via mechanisms that include inhibitory immune checkpoint molecules. Therefore, co-immunotherapy with γδ T cells plus immune checkpoint inhibitors is a strategy that may improve cytotoxicity. The use of a bispecific antibody and chimeric antigen receptor might be effective to overcome current therapeutic limitations. Such strategies should be tested in a clinical research setting.

scholarly journals An innate-like Vδ1+ γδ T cell compartment in the human breast is associated with remission in triple-negative breast cancer

2019 ◽  
Vol 11 (513) ◽  
pp. eaax9364 ◽  
Author(s):  
Yin Wu ◽  
Fernanda Kyle-Cezar ◽  
Richard T. Woolf ◽  
Cristina Naceur-Lombardelli ◽  
Julie Owen ◽  
...  
Keyword(s):  
Breast Cancer ◽  
T Cells ◽  
T Cell ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Γδ T Cells ◽  
Γδ T Cell ◽  
Human Breast ◽  
Cell Compartment ◽  
Αβ T Cells

Innate-like tissue-resident γδ T cell compartments capable of protecting against carcinogenesis are well established in mice. Conversely, the degree to which they exist in humans, their potential properties, and their contributions to host benefit are mostly unresolved. Here, we demonstrate that healthy human breast harbors a distinct γδ T cell compartment, primarily expressing T cell receptor (TCR) Vδ1 chains, by comparison to Vδ2 chains that predominate in peripheral blood. Breast-resident Vδ1+ cells were functionally skewed toward cytolysis and IFN-γ production, but not IL-17, which has been linked with inflammatory pathologies. Breast-resident Vδ1+ cells could be activated innately via the NKG2D receptor, whereas neighboring CD8+ αβ T cells required TCR signaling. A comparable population of Vδ1+ cells was found in human breast tumors, and when paired tumor and nonmalignant samples from 11 patients with triple-negative breast cancer were analyzed, progression-free and overall survival correlated with Vδ1+ cell representation, but not with either total γδ T cells or Vδ2+ T cells. As expected, progression-free survival also correlated with αβ TCRs. However, whereas in most cases TCRαβ repertoires focused, typical of antigen-specific responses, this was not observed for Vδ1+ cells, consistent with their innate-like responsiveness. Thus, maximal patient benefit may accrue from the collaboration of innate-like responses mounted by tissue-resident Vδ1+ compartments and adaptive responses mounted by αβ T cells.

scholarly journals Activation-induced Modification in the CD3 Complex of the γδ T Cell Receptor

2002 ◽  
Vol 196 (10) ◽  
pp. 1355-1361 ◽  
Author(s):  
Sandra M. Hayes ◽  
Karen Laky ◽  
Dalal El-Khoury ◽  
Dietmar J. Kappes ◽  
B.J. Fowlkes ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Ex Vivo ◽  
Γδ T Cells ◽  
Cell Receptor ◽  
Intraepithelial Lymphocytes ◽  
Subunit Composition ◽  
Γδ T Cell ◽  
Receptor Complexes ◽  
Functional Consequences

The T cell antigen receptor complexes expressed on αβ and γδ T cells differ not only in their respective clonotypic heterodimers but also in the subunit composition of their CD3 complexes. The γδ T cell receptors (TCRs) expressed on ex vivo γδ T cells lack CD3δ, whereas αβ TCRs contain CD3δ. While this result correlates with the phenotype of CD3δ−/− mice, in which γδ T cell development is unaffected, it is inconsistent with the results of previous studies reporting that CD3δ is a component of the γδ TCR. Since earlier studies examined the subunit composition of γδ TCRs expressed on activated and expanded peripheral γδ T cells or γδ TCR+ intestinal intraepithelial lymphocytes, we hypothesized that activation and expansion may lead to changes in the CD3 subunit composition of the γδ TCR. Here, we report that activation and expansion do in fact result in the inclusion of a protein, comparable in mass and mobility to CD3δ, in the γδ TCR. Further analyses revealed that this protein is not CD3δ, but instead is a differentially glycosylated form of CD3γ. These results provide further evidence for a major difference in the subunit composition of αβ- and γδ TCR complexes and raise the possibility that modification of CD3γ may have important functional consequences in activated γδ T cells.

Recovery Of Gamma/Delta+ T Cells After Transplantation With Alpha-Beta+/CD19+ Lymphocyte Depleted Hematopoietic Stem Cells From HLA-Haploidentical Donors

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3245-3245
Author(s):  
Irma Airoldi ◽  
Ignazia Prigione ◽  
Alice Bertaina ◽  
Claudia Cocco ◽  
Daria Pagliara ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Zoledronic Acid ◽  
Γδ T Cells ◽  
Leukemia Cells ◽  
Γδ T Cell ◽  
Hematopoietic Stem ◽  
Functional Studies ◽  
Αβ T Cells ◽  
Over Time

Abstract HLA-haploidentical hematopoietic stem cell transplantation (HSCT) using CD34+ selected cells is a widely used procedure, which, however, is complicated by delayed immune reconstitution. We recently developed a new method of graft manipulation based on the physical removal of αβ+ T cells and CD19+ B cells, which permits to leave mature natural killer (NK) cells and γδ+ T cells in the graft. These cells can exert a graft-versus-leukemia (GvL) effect and reduce the risk of infection. In particular, unconventional γδ T cells play a critical role in both innate and adaptive immunity and exert HLA-unrestricted cytotoxicity against both solid and hematological tumors, thus potentially acting as beneficial effector cells in transplanted patients. Moreover, such grafts may limit the risk of graft-versus-host disease and prevent EBV-related lymphoproliferative disease. We performed phenotypic and functional studies on γδ T cells collected from 20 pediatric patients (pts, 13 males, 7 females, median age 10 years, range 6 months to 16 years) that received this type of allograft. Eighteen pts had acute leukemia and 2 non-malignant disorders. Ex vivo assays of peripheral blood γδ T cell phenotype and function were performed weekly until Hospital discharge and monthly until 6 months after HSCT. Phenotype of γδ T cells was analysed by flow cytometry. Analyses were performed on mononuclear cells labelled with mAb panels (CD3, CD45, pan-γδ, anti-Vδ1, -Vδ2, -Vγ9, CD45RO, CD45RA, CD27, CD16, CD56) allowing the identification of the main γδ+ T cell subsets, including Vδ1+ and Vδ2+ cells, naïve, central memory (CM), effector memory (EM) and terminally differentiated (TD) γδ T cells. Functional studies were performed using γδ T cells shortly after collection from pts, as well as after in vitro expansion with zoledronic acid and IL-2 for 10 days. Cytotoxic activity of γδ T cells was tested against primary leukemia cells, through CD107a degranulation assay and/or standard 51Cr-release assay. In the first 4 weeks after HSCT, T cells were consistently of the γδ subset (>90% of CD45+CD3+ cells); by contrast, αβ+ T cells gradually increased over time. In approximately half of the pts, the percentage of αβ T cells exceeded that of γδ T cells already starting from 30 days after HSCT. γδ T cells consisted of Vδ2+Vγ9+ and Vδ1+Vγ9+/- cells, and marginally of the Vδ1-Vδ2-Vγ9- population. Detailed phenotypic characterization of Vδ1+ and Vδ2+ γδ T cells revealed that, at day +20 after HSCT, 44% of Vδ1+ cells were CM (identified as CD45RO+CD27+ cells), 26% naïve (CD45RO-CD27+), 21.4% TD (CD45RO-CD27-) and 6.1% EM (CD45RO+CD27-). Similarly, 55.4% of Vδ2+ γδ T lymphocytes were CM, 9.8% naïve, 11.4% TD and 23.1% EM. The proportion of the different Vδ2+ γδ T cell subset did not change significantly over time, especially when comparing that present at day +20 after HSCT (time point, TP1) with that measured 30 days after the attainment of a 1:1 ratio of αβ-to- γδ T cells (TP2) (Figure 1, left panel). By contrast, by comparing TP1 and TP2, we found that Vδ1+ CM γδ T cells decreased and EM cells increased over time, while naïve or TD Vδ1+ γδ T cells did not change (Figure 1, right panel). In transplanted pts experiencing cytomegalovirus (CMV) reactivation, γδ T cells mostly consisted of Vδ1+ cells (mean 59.8% of γδ T cells), among which 49% were TD, 22.7% EM, 18.9% CM and 10.1% naïve. Noteworthy, in transplanted pts who did not have CMV reactivation, the main γδ T cells showed a Vδ2+ phenotype. Functional studies revealed that pt-derived γδ T cells consistently expanded in vitro after exposure to zoledronic acid and IL-2, the resulting Vγ9Vδ2 population expressing mainly an EM phenotype. These Vγ9Vδ2 cells exerted cytotoxic activities against primary allogeneic leukemia cells, especially when leukemia cells were pre-treated with zoledronic acid (Figure 2). More importantly, both Vδ1+ and Vδ2+ γδ T cells obtained from transplanted pts showed cytotoxic activity against primary leukemia cells, as assessed by CD107a degranulation assay. In conclusion, we provide the first phenotypic and functional characterization of γδ T cells, analyzed over time in children transplanted with grafts depleted of αβ+ T cells and of B lymphocytes. Our results support the concept that γδ T cells are important effector cells, which can be expanded and activated after exposure to bisphosphonates and IL-2 with the aim of improving their killing capacity against leukemia cells. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Key implication of CD277/butyrophilin-3 (BTN3A) in cellular stress sensing by a major human γδ T-cell subset

Blood ◽  
2012 ◽  
Vol 120 (11) ◽  
pp. 2269-2279 ◽  
Author(s):  
Christelle Harly ◽  
Yves Guillaume ◽  
Steven Nedellec ◽  
Cassie-Marie Peigné ◽  
Hannu Mönkkönen ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Subset ◽  
Cell Receptor ◽  
Causal Link ◽  
Target Cells ◽  
Γδ T Cell ◽  
Vγ9vδ2 T Cells

Abstract Human peripheral Vγ9Vδ2 T cells are activated by phosphorylated metabolites (phosphoagonists [PAg]) of the mammalian mevalonate or the microbial desoxyxylulose-phosphate pathways accumulated by infected or metabolically distressed cells. The underlying mechanisms are unknown. We show that treatment of nonsusceptible target cells with antibody 20.1 against CD277, a member of the extended B7 superfamily related to butyrophilin, mimics PAg-induced Vγ9Vδ2 T-cell activation and that the Vγ9Vδ2 T-cell receptor is implicated in this effect. Vγ9Vδ2 T-cell activation can be abrogated by exposing susceptible cells (tumor and mycobacteria-infected cells, or aminobisphosphonate-treated cells with up-regulated PAg levels) to antibody 103.2 against CD277. CD277 knockdown and domain-shuffling approaches confirm the key implication of the CD277 isoform BTN3A1 in PAg sensing by Vγ9Vδ2 T cells. Fluorescence recovery after photobleaching (FRAP) experiments support a causal link between intracellular PAg accumulation, decreased BTN3A1 membrane mobility, and ensuing Vγ9Vδ2 T-cell activation. This study demonstrates a novel role played by B7-like molecules in human γδ T-cell antigenic activation and paves the way for new strategies to improve the efficiency of immunotherapies using Vγ9Vδ2 T cells.

scholarly journals Tumor-Associated Antigen Presentation by γδ T-Cells in Cancer Immunotherapy

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 1411-1411 ◽  
Author(s):  
Anne Marijn Kramer ◽  
Mengyong Yan ◽  
Karl S Peggs ◽  
John Anderson ◽  
Kenth Gustafsson
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Cell ◽  
Antigen Presentation ◽  
Cancer Immunotherapy ◽  
Cytotoxic T Cells ◽  
Γδ T Cells ◽  
Target Cells ◽  
Γδ T Cell ◽  
T Cell Lines

Abstract Tumor-Associated Antigen Presentation by γδ T-Cells in Cancer Immunotherapy Human γδ T-cells are considered to represent a link between innate and adaptive immunity. Their innate killing properties display a potent cytotoxic activity against solid tumors as well as lymphoid and myeloid malignancies. Subsequently, by lysing affected target cells and liberating antigen for uptake, they can differentiate into professional antigen presenting cells (pAPCs) for induction of CD4+ and CD8+ T cell responses. The degree of antigen-specific stimulation of responder T cells is increased in the presence of antibody(Ab)-assisted opsonized target cells, involving the low-affinity receptor for IgG CD16 (Fc γRIII), equivalent to that seen with mature antigen-loaded DCs. To elaborate the implications of this combined killing and pAPC function we have studied how freshly isolated as well as expanded and cloned populations of γδ T-cell subsets kill a target tumor cell, and take up and cross-present tumor-associated antigens (TAA). We performed quantitative analysis on the cellular uptake of different sizes of microspheres, analyzing the correlation between opsonization and internalization. All γδ T-cell subtypes were expanded using artificial APC, engineered to express CD86, CD137L and IL-15, and anti- γδ TCR Ab (B1). Short (EAAGIGILTV) and long (GHSYTTAEEAAGIGILTVILGVLLL) MART-1 peptides were used as antigens for γδ T-cell presentation to MART-1 TCR-transduced cytotoxic T-cells. A CFSE assay was performed to assess cytotoxic T-cell proliferation. Target cells and polysterene microspheres were opsonized with human anti-CD20 IgG1, Rituximab (RTX). CD16 function was blocked with a mouse monoclonal IgG1 anti-CD16 blocking Ab (clone LNK16). Imaging flowcytometry allowed us to quantify internalization of FITC-labeled microspheres. The Internalization Score is defined as the ratio of intensity inside the cell to the intensity of the entire cell. Both γδ T-cell lines and expanded γδ T-cell clones cultured long-term, remarkably, retain both tumor cell killing and take up tumor cell lysates or long synthetic TAA peptides and cross-present these on MHC class I to CD8+ cytotoxic T-cells in a dynamic, controllable fashion, dependent on Ab-opsonization. (Figure 1). The Ab-opsonization of 1 µm microspheres correlates with a higher receptor-mediated phagocytic uptake, in a CD16 dependent manner (Figure 2). The opsonization of 0,5 µm microspheres led to clumping of the microspheres, accounting for the lower uptake in this particular subgroup. For a lack of better alternative, moDCs have been widely used in experimental immunotherapy settings. The ease of manipulation of human γδ T-cells, the ability to be expanded ex-vivo combined with antigen presentation makes them a great potential tool for immunotherapy as a complementary or integrative strategy. Ligation of the γδ T-cell receptor at the tumor site will activate their expansion and innate killing. Yet, antigen presentation will only occur after binding of an immunoglobulin to the tumor cell, thereby activating their dual role. Our goal is to define an effective adjuvant vaccine formulation for inducing leukemia-specific cytolytic effects. We are currently investigating whether γδ T-cells can directly present and/or cross-present to cytotoxic T-cells in-vivo in a humanized mouse model. We believe that the uptake of microspheres by γδ T-cells has an impact on the development of vaccination strategies for cancer immunotherapy, as the immunization of γδ T-cells is a powerful method for the induction or reactivation of cytotoxic T cell specific responses. FIGURE 1 CFSE assay of γδ T-cell lines cross-presenting short and long MART-1 peptides to MART-1 TCR-transduced cytotoxic T-cells in a dynamic, controllable fashion, dependent on Ab-opsonization FIGURE 1. CFSE assay of γδ T-cell lines cross-presenting short and long MART-1 peptides to MART-1 TCR-transduced cytotoxic T-cells in a dynamic, controllable fashion, dependent on Ab-opsonization FIGURE 2a FIGURE 2a. FIGURE 2b FIGURE 2b. Disclosures No relevant conflicts of interest to declare.

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