Abstract
The broad and potent tumor-reactivity of innate-like γδT cells makes them valuable additions to current cancer immunotherapeutic concepts based on adaptive immunity, such as monoclonal antibodies and αβT cells. However, clinical success using γδT cells to treat cancer has so far fallen short. Efforts of recent years have revealed a striking diversity in γδT cell functions and immunobiology, putting these cells forward as true “swiss army knives” of immunity. At the same time, however, this heterogeneity poses new challenges to the design of γδT cell-based therapeutic concepts and could explain their rather limited clinical efficacy in cancer patients. This review outlines the recent new insights into the different levels of γδT cell diversity, including the myriad of γδT cell-mediated immune functions, the diversity of specificities and affinities within the γδT cell repertoire, and the multitude of complex molecular requirements for γδT cell activation. A careful consideration of the diversity of antibodies and αβT cells has delivered great progress to their clinical success; addressing also the extraordinary diversity in γδT cells will therefore hold the key to more effective immunotherapeutic strategies with γδT cells as additional and valuable tools to battle cancer.
Immunotherapy to Treat Cancer: The Era is Now
Current treatment options to fight cancer heavily rely on pharmaceutical and radiological interventions that are accompanied by substantial off-tumor toxicity and lack of clinical efficacy. Cancer immunotherapy aims to capture the specificity and memory of the immune system and holds the promise of truly targeted treatment with durable clinical responses. Recent advances in clinical trials and the approval of more and more immunotherapeutic agents by international regulatory agencies have given the field considerable momentum, a fact that is mirrored by the announcement of cancer immunotherapy as the breakthrough of the year 2013 by Science ().
So far, the vast majority of efforts aimed at utilizing the immune system to reject cancer have focused on components of adaptive immunity, including monoclonal antibodies and αβT cells. The human immune system can theoretically generate up to 1011 unique antibodies and some 1015 unique αβT cell receptors (αβTCRs) (), and controlling this vast diversity in antigen specificity for targeted immune interventions has been a major challenge for clinical implementation. Although immunoglobulins are still used in clinical practice for untargeted protection against viral infections, such as in patients with general B-cell deficiencies, the real breakthrough in clinical immunotherapy came with mastering the genetic profile of defined monoclonal antibodies. Among the first therapeutic antibodies to directly target cancer were anti-CD20 (Rituxan or Rituximab) and anti-Her2 (Herceptin or Trastuzumab) antibodies to treat B cell leukemias and breast cancer, respectively. Treatment with these antibodies, recognizing one particular antigen with a defined affinity, has underscored the therapeutic potential of truly antigen-targeted immunotherapy, as impressive clinical benefit has been reported across studies covering the last decade (, ). The clinical success of these pioneering agents has in recent years led to the development and regulatory approval of additional antibodies to target various cancers (), propelling antigen-specific antibody-based immunotherapy into mainstream cancer treatment. Similar to the evolution of clinical antibody treatment, first evidence for the anti-tumor potential of adoptively transferred αβT cells originated from the transfer of a very diverse immune population, the so called donor lymphocyte infusions, in the early 1990s, when allogeneic donor αβT cells that were infused in patients after allogeneic stem cell transplantation demonstrated potent anti-leukemia responses (). By now, these data have been complemented by remarkable clinical results obtained with strategies that aim to mobilize the tumor-reactivity of autologous T cells in cancer patients, either by the adoptive transfer of ex vivo expanded tumor-infiltrating lymphocytes (TILs) (, ) or the infusion of monoclonal antibodies that stimulate T cell activity, such as the recently approved anti-CTLA4 antibody Ipilimumab (, ). Additionally, the genetic engineering of T cells with tumor-reactive αβTCRs (, ) or antibody-based chimeric antigen receptors (CARs) () has gained increasing interest in recent years, and the first clinical trials using adoptive transfer of such gene-modified T cells have demonstrated potent and lasting anti-tumor responses in selected patients (–).
Importantly, understanding the diversity of adaptive immune repertoires and utilizing very defined specificities for therapeutic interventions has so far been not only the success but also the downside of such therapies, resulting in highly personalized cancer care that depends on antibody-based strategies (including CAR-engineered T cells) with limited numbers of targetable tumor antigens and αβT cell products that are only clinically applicable to HLA-matched patient populations. Moreover, clinical anti-tumor efficacy of αβT cell-based approaches is so far mainly restricted to particularly immunogenic tumor types, such as melanoma. Thus, there is a compelling need to call to arms alternative immune components for novel cancer immunotherapeutic concepts.
γδT Cells: The Promising Outsiders
Unconventional γδT cells, a second lineage of T cells that express a unique somatically recombined γδTCR, possess unique features to confront the limitations of adaptive-based immunotherapeutic strategies. γδT cells are rapidly activated upon encounter of pathogen-derived antigens or self molecules that are upregulated on infected or stressed cells, resembling the activation of innate immune cells that sense molecular stress signatures (, ). Importantly, γδT cells are set apart from conventional αβT cells by the fact that activation of γδT cells does not depend on antigen presentation in the context of classical MHC molecules. A preferential usage of distinct TCR γ and δ chains, which together have the potential to form a tremendous repertoire of ~1020 uniquely recombined γδTCRs (), has formed the basis for the identification of two major γδT cell subsets. γδT cells that carry Vγ9Vδ2+ TCRs are primarily found in peripheral blood, where they constitute a minor fraction of total T cells and respond to non-peptidic intermediates of the mevalonate pathway called phosphoantigens. Other γδT cells express mainly Vδ1+ or Vδ3+ chains paired with diverse γ chains (also called Vδ2neg γδT cells) and are highly enriched at mucosal sites and epithelial tissues. The effector mechanisms of γδT cells are highly similar to those of αβT cells and involve the secretion of high levels of cytokines and lysis of target cells by the release of granzymes and perforin and the engagement of FAS and TRAIL death receptors. Thus, by combining the potent effector functions of adaptive αβT cells with recognition modes that target unique classes of antigens in an innate-like manner, γδT cells are regarded as valuable sentinels that bridge innate and adaptive immunity.
Underlying the interest in γδT cells for use in cancer immunotherapy is a long-standing body of evidence indicating that γδT cells play important roles in tumor immunosurveillance. Human γδT cells display potent in vitro cytotoxicity toward a surprisingly large array of tumors, including cells derived from both solid and hematological origin (–). Importantly, γδT cells are also capable of targeting chemotherapy-resistant leukemic cells () and to kill leukemic and colon cancer stem cells () and Sebestyen and Kuball, unpublished observation). In vivo evidence for the non-redundant relevance of γδT cells in tumor immune surveillance stems from studies showing that γδT cell-deficient mice are more susceptible for developing cancer (–). Moreover, tumor-infiltrating γδT cells (γδTIL) have been observed in cancer patients with various cancers, and isolated γδTILs were shown to efficiently kill autologous tumors ex vivo, while leaving healthy cells unharmed (–). Important roles for γδT cells in tumor host defense are furthermore suggested by clinical data showing that high numbers of γδTILs in tumors of melanoma patients and elevated levels of circulating γδT cells in leukemia patients correlate with increased cancer-free survival (, ). Taken together, these studies have established a wealth of evidence for the broad tumor-targeting capabilities of γδT cells and have sparked great interest in their application in cancer immunotherapy.
Clinical Success of γδT Cells: Stuck in Diversity?
Given the broad recognition of unique classes of tumor antigens by γδT cells combined with their potent killing capacity, it is no surprise that γδT cells have been the focus of attempts to design novel cancer immunotherapeutic strategies. Of the two major γδT cell subsets, clinical trials conducted so far have exclusively focused on the stimulation of autologous Vγ9Vδ2+ γδT cells that were either activated in vivo using so-called aminobisphosphonate compounds that specifically activate Vγ9Vδ2+ γδT cells, or expanded ex vivo and reinfused into patients. Protocols for the in vivo mobilization of Vγ9Vδ2+ T cells generally involved repeated cycles of intravenous injection of synthetic phosphoantigen () or aminobisphosphonates such as pamidronate () or zoledronate (–40), in combination with multiple IL2 injections per cycle. In trials that explored the adoptive transfer autologous Vγ9Vδ2+ T cells, patient PBMCs were cultured ex vivo for 2 weeks in the presence of aminobisphosphonates (41–43) or synthetic phosphoantigen (44, 45) in combination with IL2. Even though these conditions promoted the expansion of Vγ9Vδ2+ T cells, ex vivo expanded cell products contained rather low (on average 50–60%) and highly variable percentages of Vγ9Vδ2+ T cells, and no additional purification of Vγ9Vδ2+ T cells was performed prior to reinfusion into patients. Patients received repeated infusions of expanded cells, in some trials in combination with IL2. Treatment using γδT cells was generally found to be safe using both in vivo and ex vivo stimulation protocols, but clinical responses varied widely across trials and were generally limited, even in patients with cancers generally sensitive to immune responses such as renal cell carcinoma [reviewed in Ref. (46–48)]. Important limitations included (a) the need for a preselection of patients due to a wide variability in in vitro cytotoxicity of patient γδT cells against autologous tumor tissue (, 41, 44), and (b) limited in vivo or ex vivo expansion potential of patient γδT cells (40, 41, 44, 45, 49). Moreover, anti-tumor efficacy of γδT cells showed only marginal improvement over standard treatment options (46). Thus, despite the fact that these trials have established the anti-tumor potential of γδT cells in cancer immunotherapy, current therapeutic strategies using these cells clearly suffer from major shortcomings that have so far prevented γδT cells to live up to their clinical promise.
A Remarkable Diversity Hampers Application of γδT Cells in Cancer Immunotherapy
Recent years have seen important progress in the understanding of γδT cell immunobiology and have uncovered a striking diversity in γδT cell functions and subsets. These new insights have important implications for the use of γδT cells in the treatment of cancer. To date, however, a profound appreciation of this γδT cell diversity has lacked from γδT cell-based clinical concepts and this is likely to contribute to the limited clinical results observed so far. At least three levels of γδT cell heterogeneity can be distinguished (Figure 1), including (a) a multitude of immune functions mediated by γδT cells, (b) a diverse γδTCR repertoire that, also for similar antigen-specificities, mediates different affinities, and (c) the complex and diverse molecular needs for target recognition within the same and across different γδT cell populations. A thorough consideration of these features will be of central importance to improving the clinical efficacy of γδT cells in treating cancer.
Figure 1
γδT cell functions: The more the better?
γδT cells have, as discussed above, been attributed important and valuable functions in tumor immunosurveillance, but reactivity toward tumors is far from the only part that γδT cells play in immunity. By now, it is evident that γδT cells perform a plethora of functions that underline their involvement in diverse pathophysiological conditions other than cancer, including host defense against infectious pathogens such as bacteria, viruses, and parasites, the modulation of the activity of other immune cells, and promoting tissue regenerating after injury (, 50).
Rapid expansions of γδT cells are observed in human beings infected with a variety of viruses or bacteria and γδT cells possess a potent capacity to directly kill infected cells (51). Moreover, a proportion of γδT cells contribute to pathogen clearance by the secretion of anti-microbial peptides such as granulysin and cathelicidin (52–54). Intriguingly, the recognition of pathogens may have important implications for γδT cell-mediated cytotoxicity against cancers, as subsets of γδT cells that respond to cytomegalovirus (CMV) infection have been reported to cross-recognize solid (55) as well as hematological (56) tumor cells in vitro. A role for virus-induced γδT cells in the protection from cancer in vivo is supported by observations that CMV infection in kidney transplant recipients was observed to associate with increased levels of γδT cells and concomitantly a reduced risk of developing cancer (57). Also in leukemia patients treated with hematopoietic stem cell transplantation, CMV infection associates with lower incidence of leukemic relapse after transplantation (58, 59) and work from our laboratory has demonstrated that tumor surveillance by CMV-induced γδT cells is likely to play a major role in this (56), emphasizing the clinical value of such dual-reactive γδT cells in immunotherapy.
In addition to their strong reactivity to a wide variety of tumors and pathogens, a valuable feature of γδT cells is their capability to broaden immune responses by recruiting and activating additional immune cell populations. For example, activated γδT cells have the potential to orchestrate adaptive αβT cell responses, both directly by functioning as antigen-presenting cells (60–62) as well as indirectly via the interaction with dendritic cells (56, 63, 64). In addition, γδT cells have been reported to secrete cytokines to provide B cell help in the production of antibodies (65, 66), to prime NK cells to kill tumor cells (67), to rapidly recruit neutrophils via the secretion of IL-17 (68, 69), and to synergize with monocytes to mount anti-microbial αβT cell responses (70). However, in addition to the immunostimulatory roles of γδT cells, their modulatory function may be of regulatory nature as well, suggesting complex implications of γδT cells in mediating broader immune responses. For example, depending on antigenic exposure, γδT cells may suppress rather than promote antibody production by B cells (71, 72). Similarly, γδT cells can strongly inhibit the proliferation of activated αβT cells (73, 74), and a suboptimal maturation of DCs by γδT cells (56) may induce tolerogenic rather than cytotoxic αβT cell responses. Importantly, human and mouse IL17-producing γδT cells have recently been demonstrated to facilitate tumor growth by recruiting myeloid-derived suppressor cells to tumor sites (75, 76). With the recent identification of bona fide Foxp3-expressing regulatory γδT cell subsets (77), it is thus becoming clear that, depending on their local or temporal cytokine milieu, activated γδT cells may suppress instead of activate local immune responses (78). Indeed, even though the presence of γδT cells may correlate with increased survival of cancer patients in some studies (see above), their infiltration into tumor sites may also associate with worse clinical outcome of patients due to a immunosuppressive phenotype of local γδT cells (79–81).
A very diverse γδTCR repertoire produces receptors with variable anti-tumor affinities
Like αβTCRs and B cell receptors, γδTCRs are generated during T cell maturation through the somatic recombination of germline-encoded variable (V), diversity (D), and joining (J) gene segments. Despite the fact that the number of germline Vγ and Vδ genes is far more limited than the repertoire of Vα and Vβ genes, more extensive junctional diversification processes during TCR γ and δ chain rearrangement leads to a potential γδTCR repertoire that is roughly 105-fold larger than that of αβTCRs (). Despite this extensive γδTCR repertoire, the diversity of antigens that are recognized by γδTCRs appears to be surprisingly limited. The vast majority of Vγ9Vδ2+ TCRs on circulating γδT cells are restricted to sensing elevated levels of phosphoantigens (, 82), a process that has recently been demonstrated to involve the butyrophilin family member BTN3A1 (83, 84). Similarly, all antigens of Vδ2neg γδTCRs identified so far, including MICA/B (85), CD1 (86, 87), and EPCR (88), belong to the family of non-classical MHC homologs, although additional antigens are likely to still be identified and may include MHC-unrelated molecules.
An important question is why this rather narrow antigen restriction of γδT cells is confronted with such a broad γδTCR diversity, instead of a rather oligoclonal or invariant repertoire as expressed by for example NKT cells (89). One possible explanation may be that the extensive γδTCR repertoire of γδT cells allows an important fine-tuning of γδTCR-mediated target cell recognition. Indeed, we have shown recently that phosphoantigen-responsive Vγ9Vδ2+ γδT cell clones differed widely in their functional avidity toward tumor cells (90). γδTCR transfer and mutation experiments showed that this variability in the ability to respond to tumor cells was mediated primarily through diverse sequence compositions that dictate the affinities of individual clone-derived Vγ9Vδ2+ TCRs. A similar γδTCR-mediated heterogeneity in anti-tumor specificity can be observed in the Vδ2neg subset of γδT cells, as we recently demonstrated that individual Vδ1+ γδT cell clones display γδTCR-mediated reactivity against diverse arrays of tumor cells (56). Moreover, γδTCRs of other Vδ1+ clones were not involved in tumor recognition but mediated interactions with dendritic cells, demonstrating that a diverse γδTCR repertoire can mediate not only a fine-tuning of anti-tumor avidity but also different functions. Accordingly, diverse γδT cell functions that segregate with γδTCR composition have been observed for the human Vγ9Vδ2+ and Vδ2neg subsets, as Vγ9Vδ2 γδT cells have been generally ascribed potent cytotoxic effector functions, while Vδ2neg γδT cells rather have immunomodulatory roles (91, 92). However, these observations are contrasted by reports showing a superior tumor-homing and -killing capacity of Vδ2neg γδTILs over Vγ9Vδ2 γδTILs in some cancers (, 93), further underlining the heterogeneous and context-dependent nature of both γδT cell subsets.
γδT cell activation: A complex interplay between receptors
Alongside the γδTCR, γδT cells can be activated through a variety of activating and inhibitory NK receptors (48, 94) and toll-like receptors (TLR) (95), emphasizing the innate-like nature of these unconventional T cells. Depending on the pathophysiological context, these receptors can provide costimulation to γδTCR-mediated activation signals or can activate γδT cells independent of γδTCR triggering, adding yet another level of heterogeneity and complexity to γδT cell biology. The best-studied receptor with dualistic roles in γδT cell activation is NKG2D, a natural cytotoxicity receptor (NCR) that is expressed on NK cells, most γδT cells and CD8+ αβT cells. NKG2D recognizes the non-classical MHC homologs MICA/B and ULBPs, the expression of which is upregulated on many different tumors (96, 97). On Vγ9Vδ2+ γδT cells, NKG2D can amplify γδTCR-mediated effector functions in response to MICA/B-positive target cells (98, 99). In other cases, however, sole signaling through NKG2D has been proposed to be sufficient for activating γδT cells, without requiring γδTCR engagement (100, 101). However, as most of these studies have used TCR blocking antibodies and not receptor gene-transfer experiments, the impact of TCR affinity and signaling in NKG2D-triggered γδT cell activation might have been underestimated (Gründer and Kuball, unpublished observation). Factors that determine the directly stimulatory versus costimulatory function of NKG2D are not known, but may involve signaling by polymorphic receptors such as inhibitory NK receptors (100). Apart from serving as ligand for NKG2D, MICA/B is also recognized by selected Vδ1+ γδTCRs (85). In fact, overlapping binding epitopes for NKG2D and γδTCRs on MICA/B result in competitive binding of both receptors for MIC ligands, suggestive of complex, temporally regulated interactions of both receptors for MIC ligands (102). Similarly, engagement of the NCRs NKp30, NKp44, and NKp46 on γδT cells can be sufficient for eliciting anti-tumor cytotoxicity, but interestingly only after expression of these receptors on γδT cells has been induced via triggering of the γδTCR (103). Differential involvement of the γδTCR and additional receptors has also been reported in pathophysiological processes other than cancer, as work by us and others has demonstrated that reactivity of γδT cells against CMV-infected cells may involve γδTCR-dependent (55, 104) and -independent (56) pathways, suggesting multimodal pathogen-sensing mechanisms that may involve NK receptors (48).
Recently, we have found additional evidence for a complex interplay between receptors in the response of γδT cells against tumor cells by demonstrating that CD8αα, that serves as coreceptor for selected γδTCRs as reported by us recently (56), mediates γδTCR costimulation in a manner that depends on the particular tumor cell target (Scheper and Kuball, unpublished observation). Expression of CD8αα on T cells engineered to express a tumor-reactive γδTCR was a prerequisite for recognition of all tested tumor cell lines, but coexpression of signaling-deficient CD8α variants or mutants with single residue substitutions in the extracellular domain of CD8α alongside the γδTCR differentially impacted T cell reactivity toward the different tumor targets. Even though CD8αα+ γδT cells were first identified over 20 years ago, when CD8αα was found to be commonly expressed on Vδ1+ γδT cells in the intestine but not circulating Vγ9Vδ2+ T cells (105, 106), the functional implications of CD8αα expression on γδT cells have remained rather controversial. A number of studies have reported regulatory functions for CD8αα+ γδT cells, being capable of for example inhibiting inflammatory responses in celiac disease (107) but also to suppress αβT cell-mediated responses against tumor cells (80). On the other hand, and in line with our data (56), stimulated CD8αα+ γδT cells have been reported to be as capable as CD8αα−γδT cells of secreting high levels of Th1 cytokines such as IFNγ (108). Moreover, cytokines produced by CD8αα+ but not CD8αα− γδT cells have been implicated in the controlling of R5-tropic HIV replication and persistence (109). Thus, CD8αα+ γδT cells appear to perform diverse functions depending on the context in which they are activated.
Taken together, the emerging insights into the molecular requirements for γδT cell activation and the interplay between different receptors in this process have substantially furthered our understanding of the response of γδT cells against cancer cells, but also unveil substantial challenges to the design of uniform γδT cell-based strategies for cancer immunotherapy.
Successful Translation Using γδT Cells: Picking the Right Ones
Beyond doubt, the implications of the functional and clonal heterogeneity of γδT cells for their application in the treatment of cancer are substantial, and a failure to fully recognize this diversity in clinical concepts and trial designs is likely the most important contributing factor in the limited clinical results observed with γδT cells to date. Current clinical protocols based on the broad activation of unselected γδT cells are likely to induce γδT cell populations with diverse specificities, avidities, and functions, including regulatory. Consequently, high-avidity γδT cells with strong tumor-reactivity and a desired functional profile may represent only a relatively minor population of such cell products. In addition, stimulation of γδT cells using agents that primarily depend on strong γδTCR-mediated activation, such as the use of aminobisphosphonate and phoshoantigen compounds to expand Vγ9Vδ2+ γδT cells in trials pursued to date, most likely selects for γδT cells with low affinity Vγ9Vδ2+ γδTCRs and thus, low activity on primary tumor cells. Moreover, γδTCR-based activation strategies do not necessarily mobilize γδT cells that express a repertoire of NK receptors and TLRs required to potently respond to the multimolecular stress signature of tumor cells. Thus, the selection of optimally tumor-reactive γδT cell populations will likely be a critical parameter in the design of improved cancer immunotherapeutic concepts. In principal, this would favor strategies aimed at ex vivo rather than in vivo expansion of γδT cells, since the first allows a careful monitoring and culture-dependent skewing of γδT cell phenotype and functionality that is far more challenging to accomplish using in vivo stimulation protocols. With the clinical data available so far, it is difficult to corroborate this by comparing clinical responses observed in both types of trials, as studies using adoptive transfer of ex vivo generated γδT cells have so far relied on similar stimulation protocols (aminobisphosphonate or phosphoantigen in combination with IL-2) and the potential for extended in vitro manipulation for enhanced anti-tumor efficacy has not yet been investigated (41–45, 49, 110). Importantly, ex vivo manipulation of patient γδT cells could also include a valuable enrichment of tumor-specific γδT cells with high functional avidity, for instance using selection techniques based on the upregulation of activation markers or the production of cytokines such as IFNγ by γδT cells after in vitro coculture with autologous tumor cells. Nevertheless, γδTCR repertoires vary widely among individuals (111, 112), and generating sufficient numbers of γδT cells that recognize tumors with high avidity may therefore be challenging in certain patients. Similarly, NK receptor and TLR repertoires as well as CD8α expression levels differ considerably between γδT cell subsets (56, 103, 105, 113) and between individuals (95, 114, 115), putting additional constraints on the generation of γδT cell products potently capable of rejecting cancer.
To overcome the limitations of patient γδT cell repertoires, γδTCRs with broad tumor-specificity could be identified in vitro and genetically introduced into patient-derived immune cells. Recent work by our group has demonstrated that gene-transfer of tumor-specific Vγ9Vδ2+ and Vδ1+ γδTCRs can be used to efficiently reprogram conventional αβT cells to recognize a wide variety of tumor cells (56, 90, 97). By exploiting the abundance and superior proliferation potential of αβT cells, large numbers of autologous γδTCR-engineered T cells with defined tumor-specificity can be generated ex vivo and subsequently reinfused into cancer patients. In contrast to αβTCR gene-transfer strategies, introduced TCR γ and δ chains do not dimerize with endogenous αβTCR chains (97) and therefore do not lead to the formation of unwanted TCRs with unpredictable, and potentially dangerous, specificities. Moreover, since antigen recognition by γδTCRs does not depend on classical MHC molecules, well-characterized γδTCRs that mediate superior anti-tumor functional avidities can be applied to a broad patient population without the requirement for HLA matching. Additionally, transgenic expression of γδTCRs downregulates surface expression of endogenous αβTCR chains (56, 90, 97), enabling the use of engineered cell product even in an allogeneic “off-the-shelf” fashion. The ex vivo generation of γδTCR-engineered T cells furthermore allows additional manipulation of cell products, such as the selection of T cells with highest γδTCR expression levels or T cells which express beneficial TLRs or NK receptors. Importantly, such strategies can take advantage of the valuable lessons that have been learned from efforts to apply conventional αβT cells and their receptors in cancer immunotherapy, such as evidence for the effect of the differentiation status on in vivo persistence and function of clinical T cells (116). Our group has initiated the first clinical trial using γδTCR-gene-modified T cells to treat cancer patients (scheduled to start in 2015). Donor T cells engineered with a well-characterized tumor-reactive Vγ9Vδ2+ γδTCR (90) will be administered to leukemia patients after allogeneic stem cell transplantation as part of an engineered donor lymphocyte infusion. Ex vivo manipulations of gene-modified T cell products will include the depletion of cells that express only low levels of the clinical γδTCR and adapted culturing conditions to prevent terminal differentiation of engineered T cells before infusion into patients.
Closing Remarks
Even though γδT cells have traditionally been regarded as a homogeneous immune population, important advances in the understanding of γδT cell immunobiology have revealed a striking diversity in functionality and molecular activation modes. These new insights are generally met with great enthusiasm as they give acclaim to γδT cells for their non-redundant involvement in so many pathophysiological and homeostatic processes. However, this pleiotropy of γδT cells is likely an important factor that stifles the clinical success of their application to treat cancer. As for adaptive immune interventions, it may be absolutely mandatory to carefully consider the plethora of γδT cell functions, the diversity in γδTCR specificities and affinities as well as the complex requirements for proper γδT cell activation. At the end, such broadly tumor-reactive γδT cells might be highly effective only under very defined molecular and pathophysiological conditions and therefore less broadly applicable as initially thought, though a valuable addition to current therapeutic options. This new concept represents a major challenge in the design of next generation γδT cell-based immunotherapies, and clinical trials that incorporate these exciting insights will need to be pursued to confirm the clinical potential of γδT cells in the treatment of cancer.
Statements
Author contributions
Wouter Scheper, Zsolt Sebestyen, and Jürgen Kuball wrote the manuscript; all authors agreed on the final manuscript.
Acknowledgments
We thank Mariëtte Kranendonk for critical reading of the manuscript. This work was supported by grants of ZonMW 43400003, VIDI-ZonMW 917.11.337, LSBR 0902, AICR 10-736, KWF UU-2010-4669, UU-2013-6426, and Vrienden van het UMC Utrecht.
Conflict of interest
The scheduled clinical trial using γδTCR-gene engineered T cells is supported by Miltenyi Biotec.
References
1
Couzin-FrankelJ. Breakthrough of the year 2013. Cancer immunotherapy. Science (2013) 342(6165):1432–3.10.1126/science.342.6165.1432
2
CardingSREganPJ. Gammadelta T cells: functional plasticity and heterogeneity. Nat Rev Immunol (2002) 2(5):336–45.10.1038/nri797
3
BedardPLPiccart-GebhartMJ. Current paradigms for the use of HER2-targeted therapy in early-stage breast cancer. Clin Breast Cancer (2008) 8(Suppl 4):S157–65.10.3816/CBC.2008.s.012
4
MaloneyDG. Anti-CD20 antibody therapy for B-cell lymphomas. N Engl J Med (2012) 366(21):2008–16.10.1056/NEJMct1114348
5
VacchelliEArandaFEggermontAGalonJSautes-FridmanCZitvogelLet alTrial Watch: tumor-targeting monoclonal antibodies in cancer therapy. Oncoimmunology (2014) 3(1):e27048.10.4161/onci.27048
6
van den BrinkMRPorterDLGiraltSLuSXJenqRRHanashAet alRelapse after allogeneic hematopoietic cell therapy. Biol Blood Marrow Transplant (2010) 16(1 Suppl):S138–45.10.1016/j.bbmt.2009.10.023
7
DudleyMEWunderlichJRRobbinsPFYangJCHwuPSchwartzentruberDJet alCancer regression and autoimmunity in patients after clonal repopulation with antitumor lymphocytes. Science (2002) 298(5594):850–4.10.1126/science.1076514
8
RosenbergSARestifoNPYangJCMorganRADudleyME. Adoptive cell transfer: a clinical path to effective cancer immunotherapy. Nature Rev Cancer (2008) 8(4):299–308.10.1038/nrc2355
9
HodiFSO’DaySJMcDermottDFWeberRWSosmanJAHaanenJBet alImproved survival with ipilimumab in patients with metastatic melanoma. N Engl J Med (2010) 363(8):711–23.10.1056/NEJMoa1003466
10
LipsonEJDrakeCG. Ipilimumab: an anti-CTLA-4 antibody for metastatic melanoma. Clin Cancer Res (2011) 17(22):6958–62.10.1158/1078-0432.CCR-11-1595
11
StaussHJMorrisEC. Immunotherapy with gene-modified T cells: limiting side effects provides new challenges. Gene Ther (2013) 20(11):1029–32.10.1038/gt.2013.34
12
Marcu-MalinaVvan DorpSKuballJ. Re-targeting T-cells against cancer by gene-transfer of tumor-reactive receptors. Expert Opin Biol Ther (2009) 9(5):579–91.10.1517/14712590902887018
13
MausMVGruppSAPorterDLJuneCH. Antibody-modified T cells: CARs take the front seat for hematologic malignancies. Blood (2014) 123(17):2625–35.10.1182/blood-2013-11-492231
14
MorganRADudleyMEWunderlichJRHughesMSYangJCSherryRMet alCancer regression in patients after transfer of genetically engineered lymphocytes. Science (2006) 314(5796):126–9. Epub 2006/09/02.,10.1126/science.1129003
15
RobbinsPFMorganRAFeldmanSAYangJCSherryRMDudleyMEet alTumor regression in patients with metastatic synovial cell sarcoma and melanoma using genetically engineered lymphocytes reactive with NY-ESO-1. J Clin Oncol (2011) 29(7):917–24.10.1200/JCO.2010.32.2537
16
PorterDLLevineBLKalosMBaggAJuneCH. Chimeric antigen receptor-modified T cells in chronic lymphoid leukemia. N Engl J Med (2011) 365(8):725–33.10.1056/NEJMoa1103849
17
KochenderferJNWilsonWHJanikJEDudleyMEStetler-StevensonMFeldmanSAet alEradication of B-lineage cells and regression of lymphoma in a patient treated with autologous T cells genetically engineered to recognize CD19. Blood (2010) 116(20):4099–102.10.1182/blood-2010-04-281931
18
GruppSAKalosMBarrettDAplencRPorterDLRheingoldSRet alChimeric antigen receptor-modified T cells for acute lymphoid leukemia. N Engl J Med (2013) 368(16):1509–18.10.1056/NEJMoa1215134
19
VantouroutPHaydayA. Six-of-the-best: unique contributions of gammadelta T cells to immunology. Nat Rev Immunol (2013) 13(2):88–100.10.1038/nri3384
20
BonnevilleMO’BrienRLBornWK. Gammadelta T cell effector functions: a blend of innate programming and acquired plasticity. Nat Rev Immunol (2010) 10(7):467–78.10.1038/nri2781
21
HannaniDMaYYamazakiTDechanet-MervilleJKroemerGZitvogelL. Harnessing gammadelta T cells in anticancer immunotherapy. Trends Immunol (2012) 33(5):199–206.10.1016/j.it.2012.01.006
22
MoritaCTJinCSarikondaGWangH. Nonpeptide antigens, presentation mechanisms, and immunological memory of human Vgamma2Vdelta2 T cells: discriminating friend from foe through the recognition of prenyl pyrophosphate antigens. Immunol Rev (2007) 215:59–76.10.1111/j.1600-065X.2006.00479.x
23
D’AsaroMLa MendolaCDi LibertoDOrlandoVTodaroMSpinaMet alV gamma 9V delta 2 T lymphocytes efficiently recognize and kill zoledronate-sensitized, imatinib-sensitive, and imatinib-resistant chronic myelogenous leukemia cells. J Immunol (2010) 184(6):3260–8.10.4049/jimmunol.0903454
24
TodaroMD’AsaroMCaccamoNIovinoFFrancipaneMGMeravigliaSet alEfficient killing of human colon cancer stem cells by gammadelta T lymphocytes. J Immunol (2009) 182(11):7287–96.10.4049/jimmunol.0804288
25
GirardiMOppenheimDESteeleCRLewisJMGlusacEFillerRet alRegulation of cutaneous malignancy by gammadelta T cells. Science (2001) 294(5542):605–9.10.1126/science.1063916
26
GaoYYangWPanMScullyEGirardiMAugenlichtLHet alGamma delta T cells provide an early source of interferon gamma in tumor immunity. J Exp Med (2003) 198(3):433–42.10.1084/jem.20030584
27
StreetSEHayakawaYZhanYLewAMMacGregorDJamiesonAMet alInnate immune surveillance of spontaneous B cell lymphomas by natural killer cells and gammadelta T cells. J Exp Med (2004) 199(6):879–84.10.1084/jem.20031981
28
GrohVRhinehartRSecristHBauerSGrabsteinKHSpiesT. Broad tumor-associated expression and recognition by tumor-derived gamma delta T cells of MICA and MICB. Proc Natl Acad Sci USA (1999) 96(12):6879–84.10.1073/pnas.96.12.6879
29
MaeurerMJMartinDWalterWLiuKZitvogelLHalusczcakKet alHuman intestinal Vdelta1+ lymphocytes recognize tumor cells of epithelial origin. J Exp Med (1996) 183(4):1681–96.10.1084/jem.183.4.1681
30
ChoudharyADavodeauFMoreauAPeyratMABonnevilleMJotereauF. Selective lysis of autologous tumor cells by recurrent gamma delta tumor-infiltrating lymphocytes from renal carcinoma. J Immunol (1995) 154(8):3932–40.
31
FerrariniMHeltaiSPupaSMMernardSZocchiR. Killing of laminin receptor-positive human lung cancers by tumor infiltrating lymphocytes bearing gammadelta(+) t-cell receptors. J Natl Cancer Inst (1996) 88(7):436–41.10.1093/jnci/88.7.436
32
VieyEFromontGEscudierBMorelYDa RochaSChouaibSet alPhosphostim-activated gamma delta T cells kill autologous metastatic renal cell carcinoma. J Immunol (2005) 174(3):1338–47.10.4049/jimmunol.174.3.1338
33
BialasiewiczAAMaJXRichardG. Alpha/beta- and gamma/delta TCR(+) lymphocyte infiltration in necrotising choroidal melanomas. Br J Ophthalmol (1999) 83(9):1069–73.10.1136/bjo.83.9.1069
34
GodderKTHenslee-DowneyPJMehtaJParkBSChiangKYAbhyankarSet alLong term disease-free survival in acute leukemia patients recovering with increased gammadelta T cells after partially mismatched related donor bone marrow transplantation. Bone Marrow Transplant (2007) 39(12):751–7.10.1038/sj.bmt.1705650
35
BennounaJLevyVSicardHSenellartHAudrainMHiretSet alPhase I study of bromohydrin pyrophosphate (BrHPP, IPH 1101), a Vgamma9Vdelta2 T lymphocyte agonist in patients with solid tumors. Cancer Immunol Immunother (2010) 59(10):1521–30.10.1007/s00262-010-0879-0
36
WilhelmMKunzmannVEcksteinSReimerPWeissingerFRuedigerTet alGammadelta T cells for immune therapy of patients with lymphoid malignancies. Blood (2003) 102(1):200–6.10.1182/blood-2002-12-3665
37
DieliFGebbiaNPocciaFCaccamoNMontesanoCFulfaroFet alInduction of gammadelta T-lymphocyte effector functions by bisphosphonate zoledronic acid in cancer patients in vivo. Blood (2003) 102(6):2310–1.10.1182/blood-2003-05-1655
38
DieliFVermijlenDFulfaroFCaccamoNMeravigliaSCiceroGet alTargeting human {gamma}delta} T cells with zoledronate and interleukin-2 for immunotherapy of hormone-refractory prostate cancer. Cancer Res (2007) 67(15):7450–7.10.1158/0008-5472.CAN-07-0199
39
MeravigliaSEberlMVermijlenDTodaroMBuccheriSCiceroGet alIn vivo manipulation of Vgamma9Vdelta2 T cells with zoledronate and low-dose interleukin-2 for immunotherapy of advanced breast cancer patients. Clin Exp Immunol (2010) 161(2):290–7.10.1111/j.1365-2249.2010.04167.x
40
LangJMKaikobadMRWallaceMStaabMJHorvathDLWildingGet alPilot trial of interleukin-2 and zoledronic acid to augment gammadelta T cells as treatment for patients with refractory renal cell carcinoma. Cancer Immunol Immunother (2011) 60(10):1447–60.10.1007/s00262-011-1049-8
41
NoguchiAKanekoTKamigakiTFujimotoKOzawaMSaitoMet alZoledronate-activated Vgamma9gammadelta T cell-based immunotherapy is feasible and restores the impairment of gammadelta T cells in patients with solid tumors. Cytotherapy (2011) 13(1):92–7.10.3109/14653249.2010.515581
42
NakajimaJMurakawaTFukamiTGotoSKanekoTYoshidaYet alA phase I study of adoptive immunotherapy for recurrent non-small-cell lung cancer patients with autologous gammadelta T cells. Eur J Cardiothorac Surg (2010) 37(5):1191–7.10.1016/j.ejcts.2009.11.051
43
NicolAJTokuyamaHMattarolloSRHagiTSuzukiKYokokawaKet alClinical evaluation of autologous gamma delta T cell-based immunotherapy for metastatic solid tumours. Br J Cancer (2011) 105(6):778–86.10.1038/bjc.2011.293
44
BennounaJBompasENeidhardtEMRollandFPhilipIGaleaCet alPhase-I study of Innacell gammadelta, an autologous cell-therapy product highly enriched in gamma9delta2 T lymphocytes, in combination with IL-2, in patients with metastatic renal cell carcinoma. Cancer Immunol Immunother (2008) 57(11):1599–609.10.1007/s00262-008-0491-8
45
KobayashiHTanakaYYagiJOsakaYNakazawaHUchiyamaTet alSafety profile and anti-tumor effects of adoptive immunotherapy using gamma-delta T cells against advanced renal cell carcinoma: a pilot study. Cancer Immunol Immunother (2007) 56(4):469–76.10.1007/s00262-006-0199-6
46
FisherJPHeuijerjansJYanMGustafssonKAndersonJ. Gammadelta T cells for cancer immunotherapy: a systematic review of clinical trials. Oncoimmunology (2014) 3(1):e27572.10.4161/onci.27572
47
FournieJJSicardHPoupotMBezombesCBlancARomagneFet alWhat lessons can be learned from gammadelta T cell-based cancer immunotherapy trials?Cell Mol Immunol (2013) 10(1):35–41.10.1038/cmi.2012.39
48
ScheperWGrunderCStraetemansTSebestyenZKuballJ. Hunting for clinical translation with innate-like immune cells and their receptors. Leukemia (2014) 28(6):1181–90.10.1038/leu.2013.378
49
KondoMSakutaKNoguchiAAriyoshiNSatoKSatoSet alZoledronate facilitates large-scale ex vivo expansion of functional gammadelta T cells from cancer patients for use in adoptive immunotherapy. Cytotherapy (2008) 10(8):842–56.10.1080/14653240802419328
50
HaydayAC. Gammadelta T cells and the lymphoid stress-surveillance response. Immunity (2009) 31(2):184–96.10.1016/j.immuni.2009.08.006
51
ZhengJLiuYLauYLTuW. Gammadelta-T cells: an unpolished sword in human anti-infection immunity. Cell Mol Immunol (2013) 10(1):50–7.10.1038/cmi.2012.43
52
AgerberthBCharoJWerrJOlssonBIdaliFLindbomLet alThe human antimicrobial and chemotactic peptides LL-37 and alpha-defensins are expressed by specific lymphocyte and monocyte populations. Blood (2000) 96(9):3086–93.
53
DieliFTroye-BlombergMIvanyiJFournieJJKrenskyAMBonnevilleMet alGranulysin-dependent killing of intracellular and extracellular Mycobacterium tuberculosis by Vgamma9/Vdelta2 T lymphocytes. J Infect Dis (2001) 184(8):1082–5.10.1086/323600
54
DudalSTurriereCBessolesSFontesPSanchezFLiautardJet alRelease of LL-37 by activated human Vgamma9Vdelta2 T cells: a microbicidal weapon against Brucella suis. J Immunol (2006) 177(8):5533–9.10.4049/jimmunol.177.8.5533
55
HalaryFPitardVDlubekDKrzysiekRde la SalleHMervillePet alShared reactivity of V{delta}2(neg) {gamma}{delta} T cells against cytomegalovirus-infected cells and tumor intestinal epithelial cells. J Exp Med (2005) 201(10):1567–78.10.1084/jem.20041851
56
ScheperWvan DorpSKerstingSPietersmaFLindemansCHolSet algammadeltaT cells elicited by CMV reactivation after allo-SCT cross-recognize CMV and leukemia. Leukemia (2013) 27(6):1328–38.10.1038/leu.2012.374
57
CouziLLevaillantYJamaiAPitardVLassalleRMartinKet alCytomegalovirus-induced gammadelta T cells associate with reduced cancer risk after kidney transplantation. J Am Soc Nephrol (2010) 21(1):181–8.10.1681/ASN.2008101072
58
ElmaagacliAHSteckelNKKoldehoffMHegerfeldtYTrenschelRDitschkowskiMet alEarly human cytomegalovirus replication after transplantation is associated with a decreased relapse risk: evidence for a putative virus-versus-leukemia effect in acute myeloid leukemia patients. Blood (2011) 118(5):1402–12.10.1182/blood-2010-08-304121
59
GreenMLLeisenringWMXieHWalterRBMielcarekMSandmaierBMet alCMV reactivation after allogeneic HCT and relapse risk: evidence for early protection in acute myeloid leukemia. Blood (2013) 122(7):1316–24.10.1182/blood-2013-02-487074
60
BrandesMWillimannKBioleyGLevyNEberlMLuoMet alCross-presenting human gammadelta T cells induce robust CD8+ alphabeta T cell responses. Proc Natl Acad Sci U S A (2009) 106(7):2307–12.10.1073/pnas.0810059106
61
BrandesMWillimannKMoserB. Professional antigen-presentation function by human gammadelta T Cells. Science (2005) 309(5732):264–8.10.1126/science.1110267
62
HimoudiNMorgensternDAYanMVernayBSaraivaLWuYet alHuman gammadelta T lymphocytes are licensed for professional antigen presentation by interaction with opsonized target cells. J Immunol (2012) 188(4):1708–16.10.4049/jimmunol.1102654
63
LeslieDSVincentMSSpadaFMDasHSugitaMMoritaCTet alCD1-mediated gamma/delta T cell maturation of dendritic cells. J Exp Med (2002) 196(12):1575–84.10.1084/jem.20021515
64
ContiLCasettiRCardoneMVaranoBMartinoABelardelliFet alReciprocal activating interaction between dendritic cells and pamidronate-stimulated gammadelta T cells: role of CD86 and inflammatory cytokines. J Immunol (2005) 174(1):252–60.10.4049/jimmunol.174.1.252
65
ZhengBMarinovaEHanJTanTHHanS. Cutting edge: gamma delta T cells provide help to B cells with altered clonotypes and are capable of inducing Ig gene hypermutation. J Immunol (2003) 171(10):4979–83.10.4049/jimmunol.171.10.4979
66
CaccamoNBattistiniLBonnevilleMPocciaFFournieJJMeravigliaSet alCXCR5 identifies a subset of Vgamma9Vdelta2 T cells which secrete IL-4 and IL-10 and help B cells for antibody production. J Immunol (2006) 177(8):5290–5.10.4049/jimmunol.177.8.5290
67
ManiarAZhangXLinWGastmanBRPauzaCDStromeSEet alHuman gammadelta T lymphocytes induce robust NK cell-mediated antitumor cytotoxicity through CD137 engagement. Blood (2010) 116(10):1726–33.10.1182/blood-2009-07-234211
68
CaccamoNLa MendolaCOrlandoVMeravigliaSTodaroMStassiGet alDifferentiation, phenotype, and function of interleukin-17-producing human Vgamma9Vdelta2 T cells. Blood (2011) 118(1):129–38.10.1182/blood-2011-01-331298
69
ChienYHZengXPrinzI. The natural and the inducible: interleukin (IL)-17-producing gammadelta T cells. Trends Immunol (2013) 34(4):151–4.10.1016/j.it.2012.11.004
70
EberlMRobertsGWMeuterSWilliamsJDTopleyNMoserB. A rapid crosstalk of human gammadelta T cells and monocytes drives the acute inflammation in bacterial infections. PLoS Pathog (2009) 5(2):e1000308.10.1371/journal.ppat.1000308
71
McMenaminCPimmCMcKerseyMHoltPG. Regulation of IgE responses to inhaled antigen in mice by antigen-specific gamma delta T cells. Science (1994) 265(5180):1869–71.10.1126/science.7916481
72
HuangYJinNRoarkCLAydintugMKWandsJMHuangHet alThe influence of IgE-enhancing and IgE-suppressive gammadelta T cells changes with exposure to inhaled ovalbumin. J Immunol (2009) 183(2):849–55.10.4049/jimmunol.0804104
73
KuhlAAPawlowskiNNGrollichKBlessenohlMWestermannJZeitzMet alHuman peripheral gammadelta T cells possess regulatory potential. Immunology (2009) 128(4):580–8.10.1111/j.1365-2567.2009.03162.x
74
TraxlmayrMWWeschDDohnalAMFunovicsPFischerMBKabelitzDet alImmune suppression by gammadelta T-cells as a potential regulatory mechanism after cancer vaccination with IL-12 secreting dendritic cells. J Immunother (2010) 33(1):40–52.10.1097/CJI.0b013e3181b51447
75
MaSChengQCaiYGongHWuYYuXet alIL-17A produced by gammadelta T cells promotes tumor growth in hepatocellular carcinoma. Cancer Res (2014) 74(7):1969–82.10.1158/0008-5472.CAN-13-2534
76
WuPWuDNiCYeJChenWHuGet alGammadeltaT17 cells promote the accumulation and expansion of myeloid-derived suppressor cells in human colorectal cancer. Immunity (2014) 40(5):785–800.10.1016/j.immuni.2014.03.013
77
CasettiRAgratiCWallaceMSacchiAMartiniFMartinoAet alCutting edge: TGF-beta1 and IL-15 Induce FOXP3+ gammadelta regulatory T cells in the presence of antigen stimulation. J Immunol (2009) 183(6):3574–7.10.4049/jimmunol.0901334
78
KabelitzDPetersCWeschDObergHH. Regulatory functions of gammadelta T cells. Int Immunopharmacol (2013) 16(3):382–7.10.1016/j.intimp.2013.01.022
79
MaCZhangQYeJWangFZhangYWeversEet alTumor-infiltrating gammadelta T lymphocytes predict clinical outcome in human breast cancer. J Immunol (2012) 189(10):5029–36.10.4049/jimmunol.1201892
80
PengGWangHYPengWKiniwaYSeoKHWangRF. Tumor-infiltrating gammadelta T cells suppress T and dendritic cell function via mechanisms controlled by a unique toll-like receptor signaling pathway. Immunity (2007) 27(2):334–48.10.1016/j.immuni.2007.05.020
81
YeJMaCHsuehECEickhoffCSZhangYVarvaresMAet alTumor-derived gammadelta regulatory T cells suppress innate and adaptive immunity through the induction of immunosenescence. J Immunol (2013) 190(5):2403–14.10.4049/jimmunol.1202369
82
GoberHJKistowskaMAngmanLJenoPMoriLDe LiberoG. Human T cell receptor gammadelta cells recognize endogenous mevalonate metabolites in tumor cells. J Exp Med (2003) 197(2):163–8.10.1084/jem.20021500
83
HarlyCGuillaumeYNedellecSPeigneCMMonkkonenHMonkkonenJet alKey implication of CD277/butyrophilin-3 (BTN3A) in cellular stress sensing by a major human gammadelta T-cell subset. Blood (2012) 120(11):2269–79.10.1182/blood-2012-05-430470
84
SandstromAPeigneCMLegerACrooksJEKonczakFGesnelMCet alThe intracellular B30.2 domain of butyrophilin 3A1 binds phosphoantigens to mediate activation of human Vgamma9Vdelta2 T cells. Immunity (2014) 40(4):490–500.10.1016/j.immuni.2014.03.003
85
GrohVSteinleABauerSSpiesT. Recognition of stress-induced MHC molecules by intestinal epithelial gammadelta T cells. Science (1998) 279(5357):1737–40.10.1126/science.279.5357.1737
86
SpadaFMGrantEPPetersPJSugitaMMelianALeslieDSet alSelf-recognition of CD1 by gamma/delta T cells: implications for innate immunity. J Exp Med (2000) 191(6):937–48.10.1084/jem.191.6.937
87
UldrichAPLe NoursJPellicciDGGherardinNAMcPhersonKGLimRTet alCD1d-lipid antigen recognition by the gammadelta TCR. Nat Immunol (2013) 14(11):1137–45.10.1038/ni.2713
88
WillcoxCRPitardVNetzerSCouziLSalimMSilberzahnTet alCytomegalovirus and tumor stress surveillance by binding of a human gammadelta T cell antigen receptor to endothelial protein C receptor. Nat Immunol (2012) 13(9):872–9.10.1038/ni.2394
89
BendelacASavagePBTeytonL. The biology of NKT cells. Annu Rev Immunol (2007) 25:297–336.10.1146/annurev.immunol.25.022106.141711
90
GrunderCvan DorpSHolSDrentEStraetemansTHeijhuursSet alGamma9 and delta2CDR3 domains regulate functional avidity of T cells harboring gamma9delta2TCRs. Blood (2012) 120(26):5153–62.10.1182/blood-2012-05-432427
91
O’BrienRLBornWK. Gammadelta T cell subsets: a link between TCR and function?Semin Immunol (2010) 22(4):193–8.10.1016/j.smim.2010.03.006
92
KressEHedgesJFJutilaMA. Distinct gene expression in human Vdelta1 and Vdelta2 gammadelta T cells following non-TCR agonist stimulation. Mol Immunol (2006) 43(12):2002–11.10.1016/j.molimm.2005.11.011
93
ZocchiMRFerrariniMMigoneNCasoratiG. T-cell receptor V delta gene usage by tumour reactive gamma delta T lymphocytes infiltrating human lung cancer. Immunology (1994) 81(2):234–9.
94
CorreiaDVLopesASilva-SantosB. Tumor cell recognition by gammadelta T lymphocytes: T-cell receptor vs. NK-cell receptors. Oncoimmunology (2013) 2(1):e22892.10.4161/onci.22892
95
WeschDPetersCObergHHPietschmannKKabelitzD. Modulation of gammadelta T cell responses by TLR ligands. Cell Mol Life Sci (2011) 68(14):2357–70.10.1007/s00018-011-0699-1
96
BauerSGrohVWuJSteinleAPhillipsJHLanierLLet alActivation of NK cells and T cells by NKG2D, a receptor for stress-inducible MICA. Science (1999) 285(5428):727–9.10.1126/science.285.5428.727
97
Marcu-MalinaVHeijhuursSvan BuurenMHartkampLStrandSSebestyenZet alRedirecting alphabeta T cells against cancer cells by transfer of a broadly tumor-reactive gammadeltaT-cell receptor. Blood (2011) 118(1):50–9.10.1182/blood-2010-12-325993
98
DasHGrohVKuijlCSugitaMMoritaCTSpiesTet alMICA engagement by human Vgamma2Vdelta2 T cells enhances their antigen-dependent effector function. Immunity (2001) 15(1):83–93.10.1016/S1074-7613(01)00168-6
99
NedellecSSabourinCBonnevilleMScotetE. NKG2D costimulates human V gamma 9V delta 2 T cell antitumor cytotoxicity through protein kinase C theta-dependent modulation of early TCR-induced calcium and transduction signals. J Immunol (2010) 185(1):55–63.10.4049/jimmunol.1000373
100
Rincon-OrozcoBKunzmannVWrobelPKabelitzDSteinleAHerrmannT. Activation of V gamma 9V delta 2 T cells by NKG2D. J Immunol (2005) 175(4):2144–51.10.4049/jimmunol.175.4.2144
101
LancaTCorreiaDVMoitaCFRaquelHNeves-CostaAFerreiraCet alThe MHC class Ib protein ULBP1 is a nonredundant determinant of leukemia/lymphoma susceptibility to gammadelta T-cell cytotoxicity. Blood (2010) 115(12):2407–11.10.1182/blood-2009-08-237123
102
XuBPizarroJCHolmesMAMcBethCGrohVSpiesTet alCrystal structure of a gammadelta T-cell receptor specific for the human MHC class I homolog MICA. Proc Natl Acad Sci U S A (2011) 108(6):2414–9.10.1073/pnas.1015433108
103
CorreiaDVFogliMHudspethKda SilvaMGMavilioDSilva-SantosB. Differentiation of human peripheral blood Vdelta1+ T cells expressing the natural cytotoxicity receptor NKp30 for recognition of lymphoid leukemia cells. Blood (2011) 118(4):992–1001.10.1182/blood-2011-02-339135
104
VermijlenDBrouwerMDonnerCLiesnardCTackoenMVan RysselbergeMet alHuman cytomegalovirus elicits fetal gammadelta T cell responses in utero. J Exp Med (2010) 207(4):807–21.10.1084/jem.20090348
105
DeuschKLulingFReichKClassenMWagnerHPfefferK. A major fraction of human intraepithelial lymphocytes simultaneously expresses the gamma/delta T cell receptor, the CD8 accessory molecule and preferentially uses the V delta 1 gene segment. Eur J Immunol (1991) 21(4):1053–9.10.1002/eji.1830210429
106
BucyRPChenCLCooperMD. Tissue localization and CD8 accessory molecule expression of T gamma delta cells in humans. J Immunol (1989) 142(9):3045–9.
107
BhagatGNaiyerAJShahJGHarperJJabriBWangTCet alSmall intestinal CD8+TCRgammadelta+NKG2A+ intraepithelial lymphocytes have attributes of regulatory cells in patients with celiac disease. J Clin Invest (2008) 118(1):281–93.10.1172/JCI30989
108
ClementeACambraAMunoz-SaaICrespiCPallaresLJuanAet alPhenotype markers and cytokine intracellular production by CD8+ gammadelta T lymphocytes do not support a regulatory T profile in Behcet’s disease patients and healthy controls. Immunol Lett (2010) 129(2):57–63.10.1016/j.imlet.2010.02.005
109
OmiKShimizuMWatanabeEMatsumuraJTakakuCShinyaEet alInhibition of R5-tropic HIV type-1 replication in CD4(+) natural killer T cells by gammadelta T lymphocytes. Immunology (2014) 141(4):596–608.10.1111/imm.12221
110
AbeYMutoMNiedaMNakagawaYNicolAKanekoTet alClinical and immunological evaluation of zoledronate-activated Vgamma9gammadelta T-cell-based immunotherapy for patients with multiple myeloma. Exp Hematol (2009) 37(8):956–68.10.1016/j.exphem.2009.04.008
111
MichishitaYHirokawaMGuoYMAbeYLiuJUbukawaKet alAge-associated alteration of gammadelta T-cell repertoire and different profiles of activation-induced death of Vdelta1 and Vdelta2 T cells. Int J Hematol (2011) 94(3):230–40.10.1007/s12185-011-0907-7
112
GiachinoCGranzieroLModenaVMaioccoVLomaterCFantiniFet alClonal expansions of V delta 1+ and V delta 2+ cells increase with age and limit the repertoire of human gamma delta T cells. Eur J Immunol (1994) 24(8):1914–8.10.1002/eji.1830240830
113
DarAAPatilRSChiplunkarSV. Insights into the relationship between toll like receptors and gamma delta T cell responses. Front Immunol (2014) 5:366.10.3389/fimmu.2014.00366
114
PietschmannKBeetzSWelteSMartensIGruenJObergHHet alToll-like receptor expression and function in subsets of human gammadelta T lymphocytes. Scand J Immunol (2009) 70(3):245–55.10.1111/j.1365-3083.2009.02290.x
115
VilchesCParhamP. KIR: diverse, rapidly evolving receptors of innate and adaptive immunity. Annu Rev Immunol (2002) 20:217–51.10.1146/annurev.immunol.20.092501.134942
116
CromptonJGSukumarMRestifoNP. Uncoupling T-cell expansion from effector differentiation in cell-based immunotherapy. Immunol Rev (2014) 257(1):264–76.10.1111/imr.12135
Summary
Keywords
γδT cells, cancer immunotherapy, γδT cell diversity, innate-like lymphocytes, γδTCR
Citation
Scheper W, Sebestyen Z and Kuball J (2014) Cancer Immunotherapy Using γδT Cells: Dealing with Diversity. Front. Immunol. 5:601. doi: 10.3389/fimmu.2014.00601
Received
11 September 2014
Accepted
07 November 2014
Published
20 November 2014
Volume
5 - 2014
Edited by
Dieter Kabelitz, Christian-Albrechts University Kiel, Germany
Reviewed by
Hansjörg Schild, University Medical Center of the Johannes Gutenberg-University, Germany; Maria L. Toribio, Spanish National Research Council (CSIC), Spain
Copyright
© 2014 Scheper, Sebestyen and Kuball.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Jürgen Kuball, Laboratory of Translational Immunology, Department of Hematology, University Medical Center Utrecht, Room number Q05.4.301, PO Box 85500, Utrecht 3508GA, Netherlands e-mail: j.h.e.kuball@umcutrecht.nl
This article was submitted to T Cell Biology, a section of the journal Frontiers in Immunology.
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.