Gamma 9V Delta Research Articles

Metabolic approaches to rescue antitumor Vγ9Vδ2 T-cell functions in myeloma.

Vγ9Vδ2 T cells are immune effector cells very well-suited for immunotherapy, but clinical results have been disappointing in multiple myeloma (MM) and other cancers. We have shown that Vg9Vd2 T cells are victimized prematurely by the immune suppressive tumor microenvironment (TME) established by myeloma and neighbouring cells in the bone marrow (BM) of MM patients. One major mechanism is the highly redundant expression of multiple immunecheckpoints/immune checkpoint-ligands (ICP/ICP-L) in the TME impairing antimyeloma Vg9Vd2 T-cell immune responses. Another major immune suppressive mechanism is the metabolic reset driven by myeloma cells in the TME to satisfy their energetic needs to the detriment of effector cells. Recently, it has become clear that the ICP/ICP-L circuitry and metabolic checkpoints (MCP) jointly operate in the TME of cancer patients to promote tumor cell growth and suppress antitumor immune responses. In this review, we discuss the possible interactions between ICP/ICP-L and MCP in the TME of MM patients that may compromise the immune competence of BM Vγ9Vδ2 T cells, envisaging novel combination therapies to improve the outcome of immune-based interventions.

Lysis of a Broad Range of Epithelial Tumour Cells by Human γδ T Cells: Involvement of NKG2D ligands and T‐cell Receptor‐ versus NKG2D‐dependent Recognition

Human gammadelta T cells expressing a V gamma 9V delta 2 T-cell receptor (TCR) kill various tumour cells including autologous tumours. In addition to TCR-dependent recognition, activation of NKG2D-positive gammadelta T cells by tumour cell-expressed NKG2D ligands can also trigger cytotoxic effector function. In this study, we investigated the involvement of TCR versus NKG2D in tumour cell recognition as a prerequisite to identify tumour types suitable for gammadelta T-cell-based immunotherapy. We have characterized epithelial tumour cells of different origin with respect to cell surface expression of the known NKG2D ligands MHC class I-chain-related antigens (MIC) A/B and UL16-binding proteins (ULBP), and susceptibility to gammadelta T-cell killing. Most tumour cells expressed comparable levels of MICA and MICB as well as ULBP with the exception of ULBP-1 which was absent or only weakly expressed. Most epithelial tumours were susceptible to allogeneic gammadelta T-cell lysis and in the case of an established ovarian carcinoma to autologous gammadelta T-cell killing. Lysis of resistant cells was enhanced by pre-treatment of tumour cells with aminobisphosphonates or pre-activation of gammadelta T cells with phosphoantigens. A potential involvement of TCR and/or NKG2D was investigated by antibody blockade. These experiments revealed three patterns of inhibition, i.e. preferential inhibition by anti-TCR antibody, preferential inhibition by anti-NKG2D antibody, or additive blockade by anti-TCR plus anti-NKG2D antibodies. Our results indicate for the first time that the NKG2D pathway is involved in the lysis of different melanomas, pancreatic adenocarcinomas, squamous cell carcinomas of the head and neck, and lung carcinoma.

Isopentenyl pyrophosphate-reactive Vgamma9Vdelta 2 T helper 1-like cells are the major gammadelta T cell subset recovered from lesions of patients with genital herpes.

Herpes simplex virus (HSV)-specific T cells are essential to control and resolve genital herpes (GH). To investigate the potential involvement of gamma delta T cells in GH, T cells were recovered and expanded, by mitogenic stimulation, to T cell lines from the genital lesions of 17 patients with GH and 5 control subjects who had other diseases. Relatively high numbers of gamma delta T cells--predominantly, V gamma 9V delta 2 T cells--were detected only in the T cell lines of the patients with GH. Intralesional V gamma 9V delta 2 T cell clones did not recognize HSV-infected cells, but they showed reactivity to isopentenyl pyrophosphate and Daudi cells. The T cell clones secreted interferon- gamma, tumor necrosis factor- alpha, interleukin (IL)-8, macrophage inflammatory protein-1 alpha, and RANTES (regulated on activation, normally T cell expressed or secreted), but they secreted no or limited IL-4. The results of the present study suggest the infiltration and putative involvement of isopentenyl pyrophosphate-reactive V gamma 9V delta 2 T helper 1-like cells in individuals with GH.

Features and Functions of gd T Lymphocytes: Focus on Chemokines and Their Receptors

gamma delta T cells are a distinct subgroup of T lymphocytes that are enriched at certain anatomical localizations, such as the small intestinal epithelia and other epithelia. gamma delta T cells recognize microbial antigens, such as heat shock proteins (in mice) or phosphorylated bacterial metabolites (in humans), and control the integrity of epithelia. At the effector cell level, they share with the conventional alpha beta T lymphocytes potent cytotoxic activity and the capacity to produce a variety of cytokines, including specific cytokines such as keratinocyte growth factor. Here we summarize the current knowledge on the role of chemokines and their receptors in the migration and function of gamma delta T cells. As an example, the migration of gamma delta T cells to the small intestine is guided by the chemokine receptor CCR9 and the local expression of the corresponding ligand CCL25 (also termed thymus-expressed chemokine, TECK). Chemokine receptor expression also correlates with the functional program of T cells. In this respect, the strong expression of the MIP-1 alpha/MIP-1 beta/RANTES (CCL3/CCL4/CCL5)-receptor CCR5 correlates with a T-helper 1 phenotype of human V gamma 9V delta 2-expressing gamma delta T cells. The regulation of chemokine receptors, together with the pattern of local chemokine production, plays an important role in the localization of gamma delta T cells under physiological and pathophysiological conditions, such as infection, inflammation, and tumor defense.

The role of gamma/delta T cells in progesterone-mediated immunomodulation during pregnancy: a review.

To determine if pregnancy is recognized by the immune system and if inadequate recognition of fetal antigens might result in failed pregnancy. Review of literature and current data. In the decidua gamma/delta TCR positive cells significantly increase in number. A subset of gamma/delta T cells reacts with nonpolymorphic Class I or Class I like molecules. Trophoblast recognition is mediated by the V gamma 1 subset which recognize a conserved mammalian sequence on the trophoblast. Almost all gamma/delta T cells in the decidua are activated and use the V delta 1 chain, whereas the majority of human peripheral gamma/delta lymphocytes expresses V gamma 9/V delta 2 TCR. Peripheral gamma/delta T cells of healthy pregnant women preferentially use V gamma V delta 1 chains, on the other hand, those of recurrent aborters use the V gamma 9V delta 2 combination. Signaling via the V gamma 1.4V delta 1 receptor induces a Th2 type response, whereas activation of the lymphocytes via the V gamma 9V delta 2 receptor results in increased IL-12 production and natural killer (NK) activity. In the presence of progesterone, activated lymphocytes synthesize the progesterone induced blocking factor (PIBF), which inhibits NK activity and exerts an anti abortive effect in vivo. Decidual CD56+ and gamma delta+ cells are to a high extent the same population. All decidual CD56+ cells express PIBF, thus it cannot be excluded that local production of this substance contributes to low decidual NK activity and thus to the success of the pregnancy.

CD94/NKG2 inhibitory receptor complex modulates both anti-viral and anti-tumoral responses of polyclonal phosphoantigen-reactive V gamma 9V delta 2 T lymphocytes.

Viral, bacterial, protozoal, and cancer-associated Ags elicit strong responses in human gammadelta T lymphocytes. The majority of these cells in the peripheral blood express the Vgamma9Vdelta2-encoded TCR and recognize nonpeptidic phosphoantigens without an apparent MHC restriction. We have shown that Vgamma9Vdelta2 T cells express the inhibitory CD94/NKG2 receptor for HLA class I molecules. The anti-CD94 mAb inhibits 1) the Vgamma9Vdelta2 T cell proliferation in response mycobacterial phosphoantigens and 2) the HIV-induced Vgamma9Vdelta2 T cell expansion. Vgamma9Vdelta2 T cells stimulated with nonpeptidic mycobacterial antigens produce IFN-gamma and TNF-alpha. Signaling through the CD94/NKG2 receptor interferes with the synthesis of these cytokines. The CD94/HLA class I interaction is also involved in the cytotoxic activity of Vgamma9Vdelta2 T cells. The Vgamma9Vdelta2 T cell regulation through the CD94 receptor may be important for the potentially dual function in innate immunity, i.e., 1) NK-like and 2) TCR ligand-induced cytolytic activities.

Control of self-reactive cytotoxic T lymphocytes expressing gamma delta T cell receptors by natural killer inhibitory receptors.

The majority of peripheral blood gamma delta T cells in human adults expresses T cell receptors (TCR) with identical V regions (V gamma 9 and V delta 2). These V gamma 9 V delta 2 T cells recognize the major histocompatibility complex (MHC) class I-deficient B cell line Daudi and broadly distributed nonpeptidic antigens present in bacteria and parasites. Here we show that unlike alpha beta or V gamma 9- gamma delta T cells, the majority of V gamma 9V delta 2 T cells harbor natural killer inhibitory receptors (KIR) (mainly CD94/NKG2A heterodimers), which are known to deliver inhibitory signals upon interaction with MHC class I molecules. Within V gamma 9V delta 2 T cells, KIR were mainly expressed by clones exhibiting a strong lytic activity against Daudi cells. In stark contrast, almost all V gamma 9V delta 2 T cell clones devoid of killing activity were KIR-, thus suggesting a coordinate acquisition of KIR and cytotoxic activity within V gamma 9V delta 2 T cells. In functional terms, KIR inhibited lysis of MHC class I-positive tumor B cell lines by V gamma 9V delta 2 cytotoxic T lymphocytes (CTL) and raised their threshold of activation by microbial antigens presented by MHC class I-positive cells. Furthermore, masking KIR or MHC class I molecules revealed a TCR-dependent recognition by V gamma 9V delta 2 CTL of ligands expressed by activated T lymphocytes, including the effector cells themselves. Taken together, these results suggest a general implication of V gamma 9V delta 2 T cells in immune response regulation and a central role of KIR in the control of self-reactive gamma delta CTL.

Human gamma delta T-cell recognition of Yersinia enterocolitica.

We have studied the human gamma delta T-cell response to Yersinia enterocolitica, a facultative intracellular bacterium which causes gastroenteritis and, particularly in human leucocyte antigen (HLA)-B27+ individuals, reactive arthritis (ReA). A marked proliferation of that cytotoxic gamma delta T cells is seen when Yersinia-infected lymphoblastoid cell lines or fixed intact Yersinia are added to cultures of mononuclear cells derived from the synovial fluid of ReA patients or from the peripheral blood of healthy donors. In contrast, heat-inactivated Yersinia fail to stimulate the gamma delta T-cell response. The gamma delta T-cell lines generated killed both autologous and allogeneic infected cell lines. Interestingly, a T-cell line generated from synovial fluid mononuclear cells (SFMC) killed infected autologous cell lines and a cell line matched for HLA-B27 less well than infected allogeneic target cells. gamma delta T-cell clones isolated from this line were found to express V gamma 9V delta 2 T-cell receptor (TCR) and also killed infected mismatched cells more efficiently than autologous targets. Moreover, from experiments using major histocompatability complex (MHC)-deficient cell lines, it was apparent that target cell recognition was MHC independent. Our results suggest that gamma delta T cells can be involved in immunity to Yersinia enterocolitica and should be taken into account when considering immunopathological mechanisms leading to reactive arthritis.

Human γ/δ T‐cell response to Listeria monocytogenes protein components in vitro

Listeria monocytogenes is a facultative intracellular pathogen that replicates inside mononuclear phagocytes and induces specific cellular immunity. Listeriosis encompasses many clinical syndromes and meningitis is the most frequent clinical manifestation. Human alpha/beta and gamma/delta T cells have been shown to respond to L. monocytogenes antigens and to play an important role in resistance against listerial infection. We investigated the nature of listerial ligands and the influence of the major virulence factor, listeriolysin (hly), on the stimulation of human gamma/delta T cells from healthy individuals. We found that a listerial somatic protein ligand, which is sensitive to proteinase treatment, stimulated gamma/delta T cells in vitro; the majority of Listeria-responsive gamma/delta T cells expressed V gamma 9V delta 2 T-cell receptor chains and human leucocyte antigen-DR molecules; gamma/delta T-cell responses to hly+ and hly- Listeria strains were comparable; L. monocytogenes strains of different virulence stimulated gamma/delta T cells equally. Thus, protein components of L. monocytogenes unrelated to virulence activate human gamma/delta T cells in vitro.

Repertoire analysis of human peripheral blood lymphocytes using a human V delta 3 region-specific monoclonal antibody. Characterization of dual T cell receptor (TCR) delta-chain expressors and alpha beta T cells expressing V delta 3J alpha C alpha-encoded TCR chains.

V delta 3 usage and combinatorial expression of V gamma and V delta regions was studied on peripheral T cells with a novel V delta 3-specific mAb (p11.10b), generated against a soluble V gamma 9V delta 3 TCR. V delta 3+ cells represented the vast majority of V delta 1/V delta 2- gamma delta T cells within peripheral blood and mucosal lymphocytes. No preferential V gamma region expression was noted within V delta 3+ cells, but the frequency of V gamma 9+ cells was significantly lower among V delta 3+ than among V delta 1+ or V delta 2+ PBL. Phenotypic analysis of cultured V delta 3+ cells sorted with p11.10b mAb revealed the presence of T lymphocytes with unusual phenotypes. First, cells carrying two distinct surface TCR delta-chains, recognized by both V delta 1- and V delta 3-specific mAbs, were detected in most T cell lines, though at frequencies much lower than that of dual gamma expressors, indicating that allelic exclusion of delta genes is more tightly regulated than that of gamma genes. Moreover, a significant fraction of V delta 3+ cells were recognized by C beta- but not C delta-specific mAbs. Molecular analysis of V delta 3+C beta+ clones revealed the presence of V delta 3J alpha C alpha transcripts in all of them. Given the peculiar location of the V delta 3 gene between the delta Rec/psi J alpha elements, those observations formally demonstrate that activation of rearrangements with J alpha elements is not necessarily preceded by a delta Rec/psi J alpha-mediated deletion of the delta locus on the same chromosome.

Early activation of human V gamma 9V delta 2 T cell broad cytotoxicity and TNF production by nonpeptidic mycobacterial ligands.

Human V gamma 9V delta 2 T cells were shown recently to respond to nonpeptidic phosphorylated molecules of mycobacterial origin (previously referred to as TUBag). To investigate the early events of V gamma 9V delta 2 T cell activation, we have analyzed induction of cytotoxicity and TNF production of T cell clones by these molecules. We showed that within minutes after exposure, TUBag induced cytotoxicity of V gamma 9V delta 2 CTL (but not of CTL expressing other TCR V gamma/V delta or V alpha/V beta regions) against a broad set of target cells, including effector cells themselves. Induction of V gamma 9V delta 2 cytotoxicity by TUBag was blocked by anti-TCR mAbs and was abrogated after dephosphorylation of TUBag. Similarly, TUBag, but not dephosphorylated TUBag, induced massive TNF production by V gamma 9V delta 2 T cell clones only, which already was significant 20 min after exposure. Of note, only basal amounts of TNF were produced when cells were maintained in suspension in the presence of TUBag, indicating that efficient activation of TNF production induced by these compounds required a cell-to-cell contact. Finally, preincubation experiments allowed us to demonstrate that activation of V gamma 9V delta 2 T cells was strictly dependent on the presence of TUBag because preincubation of the targets with TUBag followed by a single wash abrogated the activation. Taken together, these results strongly suggest that activation of V gamma 9V delta 2 cells by TUBag occurs after binding of these compounds to (a) yet unidentified, highly conserved, and broadly distributed molecule(s). The results also suggest either that TUBag induces a very rapid and transient expression of a V gamma 9V delta 2 TCR ligand or, more likely, that TUBag is a low affinity component of a complex recognized by the V gamma 9V delta 2 TCR.

Phosphate is essential for stimulation of Vγ9Vδ2 T lymphocytes by mycobacterial low molecular weight ligand

T lymphocytes are divided into two subsets which express different T cell receptor heterodimers. In the peripheral blood of healthy individuals, the majority of T cells express the alpha/beta T cell receptor (> 90%) while a minority have the gamma/delta T cell receptor (< 10%). The gamma/delta T cells of adults use preferentially the V gamma 9V delta 2 chain combination. Although the stimulation requirements for gamma/delta T lymphocytes are still undetermined, it has been reported that gamma/delta T cells are not only stimulated, like alpha/beta T cells, by conventional protein antigens and superantigens, but also by unusual ligands. Mycobacteria selectively stimulate V gamma 9V delta 2 T cells, and a nonproteinacious low molecular weight fraction of 1-3 kDa has been identified as the tentative active component. Here, we confirm the nonproteinacious nature of this ligand, and show that it is comprised of unusual carbohydrate and phosphate. Importantly, cleavage of the terminal phosphate by alkaline phosphatase completely abrogates the stimulatory activity of the low molecular weight ligand for V gamma 9V delta 2 T cells. Even mycobacterial whole lysate loses its stimulatory activity, for this T cell subset, after dephosphorylation with alkaline phosphatase. These findings identify phosphocarbohydrates as a novel molecular entity with selective stimulatory activity for a defined T cell subset.

Human peripheral blood gamma delta T cells respond to antigens of Plasmodium falciparum.

Peripheral blood lymphocytes from donors previously unexposed to malaria parasites proliferate in vitro when stimulated with whole parasitized red blood cells of several different strains of Plasmodium falciparum. Here we show that both cells enriched for both memory (CD45R0+) and naïve (CD45R0-) phenotype can respond. Cells involved in these responses occur at frequencies similar to those observed for recall antigens such as tetanus toxoid but at lower frequencies than observed for the superantigens staphylococcal enterotoxin B or the mitogenic lectin phytohemagglutinin (PHA). Proliferation is inhibited by antibodies to class II MHC and to CD3 molecules. Stimulation of purified CD45R0- T cells by whole parasitized red blood cells for 6 days results in the generation of a large proportion of gamma delta T cell blasts of V gamma 9V delta 2 TCR phenotype and in the acquisition of the CD45R0 molecule within the blast cell population. The rapid generation of a vigorous primary in vitro gamma delta T cell response by malarial parasites may reflect the situation during primary malarial infection.