Gamma-delta T lymphocytes in anti-viral and anti-tumor immunity

Our team is dedicated to understand the bioactivity and the activation modalities of gamma-delta T cells. Gamma-delta T cells are T lymphocytes at the interface between innate and adaptive immunity. They preferentially localize in epithelia where they represent a major population of intraepithelial T lymphocytes (IEL). Gamma-delta T cells can respond to stressed, infected or transformed cells by secreting cytokines (mainly IFNgamma and TNFalpha) and by killing their targets. They are believed to be involved in immune surveillance but their precise functions have remained much more enigmatic than that of conventional alpha-beta T lymphocytes, probably because of their ability to act either as effectors or immunoregulatory cells (depending on circumstances). Our interest in transplantation immunology led us to demonstrate an implication of a subset of gamma-delta T cells (Vdelta2neg gamma-delta T cells) in the immune response to cytomegalovirus (CMV), a common opportunistic pathogen in immunosuppressed individuals. By combining clinical and in vitro investigations, we got insights into the interactions between gamma-delta T cells and their targets: CMV-infected cells but also tumour epithelial cells. Our aim is to clarify the precise role of gamma-delta T cells in the surveillance of viral infection or transformation, and to unravel the molecular recognition of cellular stress signals by gamma-delta T cells on their targets. We plan to achieve these goals through both in vivo studies in mouse models and diverse in vitro approaches.

Our projects are driven by the idea that the acquisition of basic knowledge on gamma-delta T cell biological functions should provide tools for the elaboration of a novel type of anti-viral or anti-tumour immunotherapy.

People involved: Myriam Capone, Lionel Couzi, Julie Déchanet-Merville, Pierre Merville, Sonia Netzer, Angela Pappalardo, Vincent Pitard

  • 1.1 Characterization of stress induced self-antigens recognized by CMV-induced gamma-delta T cells

    We follow on the characterization of antigenic ligands recognized by CMV-induced γδ T cells. Four γδ TCR antigenic ligands have already been identified for which we want to get insight into (i) their representativity as γδ T cell antigens, (ii) the mechanism leading to their recognition as stress antigens and molecular determinants of Ag/γδ TCR interaction and (iii) the stress conditions leading to their expression.

  • 1.2 How constitutively expressed self-antigens can modulate gamma-delta T cell homeostatic versus defense functions?

    From the striking observation that constitutively expressed membrane molecules can compose antigens for γδ T cells, we raised the hypothesis that such self antigens could trigger homeostatic functions of γδ T cells at steady state. Tissue γδ T cells are actually considered to play an important role in tissue integrity. In mice, skin γδ T cells have an essential role to the wound healing response and tissue surveillance (MacLeod, J Immunol, 2014) probably involving a constant γδ TCR triggering by keratinocyte (Chodaczek, Nat Immunol, 2012). This is also true for γδ IEL that are crucial to maintain epithelial barrier (Chen, PNAS , 2002) and which TCR is constantly triggered, probably by epithelial cells (Malinarich, EJI, 2010). We thus postulate that constitutive antigens permanently engage their cognate γδ TCR and trigger basal γδ T cell functions beneficial for tissue integrity (production of trophic factors, etc..). During stress conditions (wound, infection, transformation..), antigen overexpression, induction of co-stimulatory ligands (ICAM-1, NKG2D-ligands, CD58, CD155, etc..), production of inflammatory cytokines (IFNalpha, IL18 etc) could reprogram γδ T cells toward immune functions (cytotoxicity, IFNγ IL17 or chemokine production ..). We believe that CMV infection is an interesting model to test this hypothesis since steady state can be recapitulated using uninfected normal cells (fibroblasts or endothelial cells) and stress conditions can be induced by CMV-infection. 

People involved: Myriam Capone, Lionel Couzi, Julie Déchanet-Merville, Hannah Kaminski, Layal Massara, Maria Mamani-Matsuda, Pierre Merville, Sonia Netzer, Vincent Pitard

  • 2.1 APC functions of gamma-delta T cells in malaria

    Our previous work deciphered how blood stages of Plasmodium falciparum can stimulate and be targeted by gamma-delta T cells. In addition to their well-documented cytotoxic role, Vgamma9Vdelta2 T cells could mimic dendritic cell (DC) function and licence primary alpha-beta T cell responses upon stimulation by phosphoantigens. Considering both in vitro and ex vivo evidence that Plasmodium iRBC inhibit effective DC maturation and function, we investigate wether, in the context of malaria, Vgamma9Vdelta2 T cells could represent an alternative to conventional APCs.

  • 2.2 Deciphering gamma-delta T cell anti-CMV responses in the mouse

     The mouse model of CMV infection and the use of gamma-delta/alpha-betaT cell deficient hosts allowed demonstrating the protective role of gamma-deltaT cells against mouse CMV (MCMV). Indeed, TCRalpha-/- mice controlled MCMV replication/dissemination in organs and survived in contrast to CD3epsilon-/- mice. In MCMV infected TCRalpha-/- mice however, NK cells were the key producers of IFNgamma and cytolytic granules, opening new perspectives concerning the function ofgamma-delta T cells in this model.

  • 2.3 Antitumour function of MCMV-induced gamma-delta T cells

    The recognition by gamma-delta TCRs of stress antigens induced by carcinogenesis or CMV-infection suggests that CMV-induced gamma-delta T cells can also be involved in tumour control. The mouse model of CMV infection thus appears as a good opportunity to test this hypothesis in vivo. We recently showed that acute MCMV infection hampers the growth of different carcinoma cell lines in immunodeficient mice, suggesting that in the absence of immunity, high viral loads have a direct anti-tumour effect that remains to be determined. We aim now to determine whether in a latent phase of infection, MCMV-primed gamma-delta T cells acquire anti-tumour functions. 

People involved: Valérie Calco, Charlotte Domblides, Benjamin Faustin, Julie Déchanet-Merville.

  • 3.1 Regulation of human γδ T cell activation by inflammasomes

     Nod-Like Receptor (NLR) inflammasomes are major components of the innate immune host response to both infection and cell stress. The inflammasome is a protein complex that assembles in response to various infections or cell stressors (including metabolic stress) to activate inflammatory caspases such as caspase-1. In turn, active caspase-1 maturates IL-1β and IL-18 cytokines to be secreted and to trigger the adaptive immune response.

    Epithelial stress that occurs during carcinogenesis or CMV infection are known to be associated with similar metabolic changes (called the Warburg effect), which in turn could prime γδ T lymphocytes. Interestingly, these metabolic changes are essential for the production of inflammatory cytokines IL-1β and IL-18 by inflammasomes. We recently showed that inflammasomes are expressed and activated in CMV-infected and cancer cells to secrete IL-18. In turn, IL-18 alone can stimulate γδ T cell effector functions, contrarily to αβ T cells. Importantly, IL-18 sensing by γδ T cells depends on TCR engagement. Hence, we propose that inflammasome activation in target cells represents a stress signal pathway that triggers γδ T cell activation.

  • 3.2 Sensing of metabolic stress by γδ T cells

     Since metabolic changes induced by both carcinogenesis and CMV infection are similar, we want to investigate how the metabolic reprogramming of these cells may influence the mechanisms involved in γδ T cell activation. By modifying the composition of cell culture medium, our results show that switching the metabolism of cancer cells from aerobic glycolysis (Warburg effect) to the mitochondrial oxidative metabolism induces two different mechanisms of γδ T cell activation, i.e an increased expression of stress antigens and also the release of soluble activators by cancer cells. We plan to investigate if modulating the activities of metabolic reprogrammers such as the energy sensor AMPK, and starvation sensor mTOR can recapitulate these findings. The results may lead to identifying stress signalling involved in target cell recognition by T cells and shed light on specific targets to manipulate them (collaboration with R. Rossignol, MRGM EA, Victor Segalen Bordeaux University). Hence, γδ T cells can sense metabolic stress of cancer cells through two different mechanisms: variation of stress antigen expression and detection of secreted molecules.

People involved: Layal Massara, Julie Déchanet-Merville, Pierre Merville, Jonathan Visentin

Knowledge on the role of gamma-delta T cells in humoral response remains fragmented. Germinal center formation and production of class-switched antibodies occurs efficiently in alpha-betaT cell deficient mice (35). Many of the antibodies synthesized in these mice are reactive to a similar spectrum of self-antigens as that targeted by autoantibodies characterizing human SLE.  gamma-delta T cells have been shown to provide help for the production of these antibodies (including autoantibodies). In humans, gamma-delta T cells express CD154 and ICOS upon in vitro activation, a subset of  gamma-delta T cells with a Tfh profile are found in blood and tonsils, and patients with  alpha-beta T cell deficiencies and elevated levels of  gamma-delta T cells have normal levels of Igs (36-38). We want to take advantage of  gamma-delta T cell response to CMV as a model to study the cooperation between  gamma-delta T cells and B cells. Since gamma-delta T cells recognize self-antigens, are they able to activate or to control autoreactive B cells recognizing the same self-antigens? How does this affect or contribute to self tolerance?


Photo: “ALySAI”

by Marie-Désirée Smith



Main Publications

Phosphoantigen burst upon Plasmodium falciparum schizont rupture can distantly activate Vgamma9-Vdelta2 T-cells. Guenot M, Loizon S, Howard J, Costa G, Baker DA, Mohabeer SY, Troye-Blomberg M, Moreau JF, Dechanet-Merville J, Mercereau-Puijalon O, Mamani-Matsuda M and Behr C. Infect Immun. 2015, Oct;83(10):3816-24

Surveillance of γδ T Cells Predicts Cytomegalovirus Infection Resolution in Kidney Transplants. Kaminski H, Garrigue I, Couzi L, Taton B, Bachelet T, Moreau JF, Déchanet-Merville J, Thiébaut R, and Merville P. J Am Soc Nephrol. 2016, Feb;27(2):637-45

TCR-dependent sensitization of human gamma-delta T cells to non-myeloid IL18 in CMV and tumour stress surveillance. Guerville F, Daburon S, Marlin R, Lartigue L, Loizon S, Pitard V, Couzi L, Moreau JF, Déchanet-Merville J and Faustin B, Oncoimmunology 2015, Feb 3;4(5):e1003011

Gamma-delta T Cells Confer Protection against Murine Cytomegalovirus (MCMV). Khairallah C, Netzer, Villacreces A, Juzan M, Rousseau B, Dulanto S, Giese A, Costet P, Praloran V, Moreau JF, Dubus P, Vermijlen D, Déchanet-Merville J and Capone M. Plos Pathogens (2015) Mar 6;11(3):e1004702.

Cytomegalovirus-responsive gamma-delta T cells: novel effector cells in antibody-mediated kidney allograft microcirculation lesions. Bachelet T, Couzi L, Pitard V, Sicard X, Rigothier C, Lepreux S, Moreau JF, Taupin JL, Merville P, Déchanet-Merville J. J Am Soc Nephrol. (2014) Nov;25(11):2471-82.

Anti-metastatic potential of human Vdelta1+ gamma-delta T cells in an orthotopic mouse xenograft model of colon carcinoma. Devaud C, Rousseau B, Netzer S, Pitard V, Paroissin C,  Khairallah C, Costet P, Moreau JF, Couillaud F, Dechanet-Merville J and Capone M. Cancer Immunol Immunother (2013) Jul;62(7):1199-210.

CMV and tumor stress-surveillance by human gamma-delta T cell receptor binding to Endothelial Protein C Receptor. Willcox C*, Pitard V*, Netzer S, Couzi L, Salim M, Silberzahn T, Moreau JF, Hayday A, Willcox B*, and Déchanet-Merville J*. *equal contributors Nat Immunol (2012) 13: 872-879. News and Views on this paper p813-814.

Antibody-dependent anti-cytomegalovirus activity of human gamma-delta T cells expressing CD16 (FcgammaRIIIa). Couzi L, Pitard V, Sicard, X, Garrigue I, Hawchar O, Merville P, JF Moreau and Déchanet-Merville J. Blood (2012) 119:1418-27.

Control of Plasmodium falciparum erythrocytic cycle: γδ T cells target the red blood cell-invasive merozoites. Costa G, Loizon S, Guenot M, Mocan I, Halary F, de Saint-Basile G, Pitard V, Déchanet-Merville J, Moreau JF, Troye-Blomberg M, Mercereau-Puijalon O and Behr C. Blood (2011) Dec 22;118(26):6952-62.

CMV-induced gamma-delta T cells associate with reduced cancer risk after kidney transplantation. Couzi L, Levaillant Y, Jamai A, Pitard V, Lassalle R, Martin K, Garrigue I, Hawchar O, Siberchicot F, Moore N, Moreau J-F, Dechanet-Merville J and Merville P. J Am Soc Nephrol. (2010) 21: 181-188. Editorial on this paper p11-13

Common features of gamma-delta T cells and CD8+ alpha-beta T cells responding to human Cytomegalovirus infection in kidney transplant recipients. Couzi L, Pitard V, Netzer S, Garrigue I, Lafon M-E, Moreau J-F, Taupin J-L, Merville P and Déchanet-Merville J. J. Infect. Dis. (2009) 200 : 1415–1424

Anti-tumor activity of gamma-delta T cells reactive against cytomegalovirus-infected cells in a mouse xenograft tumor model. Devaud C, Bilhère E, Loizon S, Pitard V, Behr C, Moreau J-F, Déchanet-Merville J and Capone M. Cancer Research, (2009) 69: 3971-3978.

Long term expansion of effector/memory Vdelta2neg gamma-delta T cells is a specific blood signature of CMV infection. Pitard V, Roumanes D, Lafarge X, Couzi L, Garrigue I, Lafon M-E, Merville P, Moreau JF and Déchanet-Merville J. Blood (2008) 112: 1317-1324.

Expression of MHC-Class I receptors confers functional intraclonal heterogeneity to a reactive expansion of gamma-delta T cells. Lafarge X, Pitard V, Ravet S, Roumanes D, Halary F, Dromer C, Vivier E, Paul P, Moreau JF, Déchanet-Merville J. Eur. J. Immunol. (2005) 35: 1896-1905.

Shared reactivity of Vdelta2neg gamma-delta T cells against CMV-infected cells and tumor intestinal epithelial cells. Halary F, Pitard V, Dlubek D, Krzysiek R, de la Salle H, Merville P, Dromer C, Emilie D, Moreau JF and Déchanet-Merville J. J. Exp. Med. (2005) 201: 1567-1578. Commentary on this paper p. 1521

Human cytomegalovirus binding to DC-SIGN is required for dendritic cell infection and target cell trans-infection. Halary F, Amara A, Lortat-Jacob H, Messerle, Delaunay T, Houlès C, Fieschi F, Arenzana-Seisdedos F, Moreau J-F, Déchanet-Merville J. Immunity (2002) 17: 653-664. « Highlight » on this paper in Nature Review Immunol. (2003, 3:8)

Reviews & Editorials

Direct and Indirect Effects of Cytomegalovirus-induced gd T Cells after Kidney Transplantation. Couzi L, Pitard V, Merville P, Moreau JF and Déchanet-Merville J, Frontiers in Immunology (2015) Jan 21;6:3.

Promising cell-based immunotherapy using gamma delta T cells: together is better.Déchanet-Merville J. Clin Cancer Res. (2014) Nov 15;20(22):5573-5.

Harnessing γδ T cells in anticancer immunotherapy. Hannani D, Ma Y, Yamazaki T, Déchanet-Merville J, Kroemer G and Zitvogel L. Trends in Immunology (2012) 33: 199-206.

Vdelta2-negative gamma-delta T cells, a multi-reactive tissue subset : from innate to adaptive altered-self surveillance. Behr C, Capone M, Couzi L, Taupin JL and Déchanet-Merville Open Immunol J. (2009) 2 : 106-118


  • Laurent Genestier (CRBL, Lyon)
  • Olivier Thaunat (CIRI, Lyon)
  • Emmanuel Scotet (CRCNA, Nantes)
  • Odile Mercereau-Puijalon (Institut Pasteur, Paris)





  • Gavin Wilkinson & Ceri Fieldings (Division of Infection and Immunity, Cardiff University)
  • Bernhard Moser & Matthias Eberl (Division of Infection and Immunity, Cardiff University)
  • Benjamin Willcox (CRUK Cancer Centre Institute of Immunology and Immunotherapy, Birmingham)
  • David Vermijlen (Institute for Medical Immunology (IMI), Université Libre de Bruxelles )
  • Bruno Silva-Santos (Instituto de Medicina Molecular, Lisbon)
  • Carlos Vilches (Hospital Univ. Puerta de Hierro, Madrid)
  • Paul Fisch (Institut für Klinische Pathologie, Frieburg)
  • Ralph Budd (The University of Vermont College of Medicine, Burlington)
  • Mark Davis (Stanford, California)