Interleukin-23-Independent IL-17 Production Regulates Intestinal Epithelial Permeability.

Whether interleukin-17A (IL-17A) has pathogenic and/or protective roles in the gut mucosa is controversial and few studies have analyzed specific cell populations for protective functions within the inflamed colonic tissue. Here we have provided evidence for IL-17A-dependent regulation of the tight junction protein occludin during epithelial injury that limits excessive permeability and maintains barrier integrity. Analysis of epithelial cells showed that in the absence of signaling via the IL-17 receptor adaptor protein Act-1, the protective effect of IL-17A was abrogated and inflammation was enhanced. We have demonstrated that after acute intestinal injury, IL-23R(+) γδ T cells in the colonic lamina propria were the primary producers of early, gut-protective IL-17A, and this production of IL-17A was IL-23 independent, leaving protective IL-17 intact in the absence of IL-23. These results suggest that IL-17-producing γδ T cells are important for the maintenance and protection of epithelial barriers in the intestinal mucosa.

High-throughput Raman spectroscopy allows ex vivo characterization of murine small intestinal intra-epithelial lymphocytes (IEL).

T cells are considered to be critical drivers of intestinal inflammation in mice and people. The so called intra-epithelial lymphocyte (IEL) compartment largely consist of T cells. Interestingly, the specific regulation and contribution of IELs in the context of inflammatory bowel disease remains poorly understood, in part due to the lack of appropriate analysis tools. Powerful, label-free methods could ultimately provide access to this cell population and hence give valuable insight into IEL biology and even more to their disease-related functionalities. Raman spectroscopy has demonstrated over the last few years its potential for reliable cell characterization and differentiation, but its utility in regard to IEL exploration remains unknown. To address this question experimentally, we utilized a murine, T cell-driven experimental model system which is accepted to model human gut inflammation. Here, we repopulated the small intestinal IEL compartment (SI IELs) of Rag1-deficient mice endogenously lacking T cells by transferring naïve CD4+ T helper cells intraperitoneally. Using multivariate statistical analysis, high-throughput Raman spectroscopy managed to define a cell subpopulation ex vivo within the SI IEL pool of mice previously receiving T cells in vivo that displayed characteristic spectral features of lymphocytes. Raman data sets matched flow cytometry analyses with the latter identifying T cell receptor (TCR)αß+ CD4+ T cell population in SI IELs from T cell-transferred mice, but not from control mice, in an abundance comparable to the one detected by Raman spectroscopy. Hence, in this study, we provide experimental evidence for high-throughput Raman spectroscopy to be a novel, future tool to reliably identify and potentially further characterize the T cell pool of small intestinal IELs ex vivo.

Acute upregulation of an NKG2D ligand promotes rapid reorganization of a local immune compartment with pleiotropic effects on carcinogenesis.

The self-encoded ligands MICA (human) and Rae-1 (mouse) for the cytotoxic lymphocyte activating receptor NKG2D are highly expressed in carcinomas and inflammatory lesions and have been linked to immunosurveillance and graft rejection. However, whether NKG2D ligands have an intrinsic ability to acutely regulate tissue-associated immune compartments is not known. Here we show that epidermis-specific upregulation of Rae-1 induced rapid, coincident and reversible changes in the organization of tissue-resident V(gamma)5V(delta)1 TCRgammadelta+ intraepithelial T cells and Langerhans cells, swiftly followed by epithelial infiltration by unconventional alphabeta T cells. Whereas local V(gamma)5V(delta)1+ T cells limited carcinogenesis, Langerhans cells unexpectedly promoted it. These results provide unique insight into the early phases of tissue immunosurveillance and indicate that acute changes in NKG2D ligands may alone initiate a rapid, multifaceted immunosurveillance response in vivo.

Early Pregnancy Human Decidua is Enriched with Activated, Fully Differentiated and Pro-Inflammatory Gamma/Delta T Cells with Diverse TCR Repertoires.

Pregnancy is a state where high and stage-dependent plasticity of the maternal immune system is necessary in order to equilibrate between immunosuppression of harmful responses towards the fetus and ability to fight infections. TCR γδ cells have been implicated in the responses in infectious diseases, in the regulation of immune responses, and in tissue homeostasis and repair. The variety of functions makes γδ T cells a particularly interesting population during pregnancy. In this study, we investigated the proportion, phenotype and TCR γ and δ repertoires of γδ T cells at the maternal⁻fetal interface and in the blood of pregnant women using FACS, immunohistochemistry and spectratyping. We found an enrichment of activated and terminally differentiated pro-inflammatory γδ T-cell effectors with specific location in the human decidua during early pregnancy, while no significant changes in their counterparts in the blood of pregnant women were observed. Our spectratyping data revealed polyclonal CDR3 repertoires of the δ1, δ2 and δ3 chains and γ2, γ3, γ4 and γ5 chains and oligoclonal and highly restricted CDR3γ9 repertoire of γδ T cells in the decidua and blood of pregnant women. Early pregnancy induces recruitment of differentiated pro-inflammatory γδ T-cell effectors with diverse TCR repertoires at the maternal⁻fetal interface.

IL-23 Activated γδ T Cells Affect Th17 Cells and Regulatory T Cells by Secreting IL-21 in Children with Primary Nephrotic Syndrome.

This study (1) analysed the percentage of γδ T cells, γδ T cell subsets, Th17 cells and regulatory T cells (Treg cells) and (2) determined the role of IL-23 in primary nephrotic syndrome (PNS) patients with active disease and in remission. Eighty-four patients with PNS and 51 healthy age-matched controls were included in this study. The percentage of γδ T cells, γδ T cell subsets, Th17 cells and Treg cells in peripheral blood mononuclear cells (PBMCs) were analysed by fluorescence-activated cell sorting. PMBCs from PNS patients with active disease were cultured in the presence of IL-23, IL-23 and an IL-23 antagonist, or IL23 and an anti-IL-21 monoclonal antibody (mAb). The percentage of γδ T cells, IL-23R+ γδ T cells and IL-17+ γδ T cells were significantly increased in PNS patients with active disease. There was a positive correlation between the percentage of γδ T cells, IL-23R+ γδ T cells, IL-17+ γδ T cells and the Th17/Treg ratio. IL-23 increased the percentage of γδ T cells and Th17 cells and decreased the percentage of Treg cells in PBMCs isolated from PNS patients with active disease. Anti-IL-21 mAb reduced the percentage of γδ T cells and Th17 cells, but increased the percentage of Treg cells. γδ T cells, IL-17+ γδ T cells and IL-23R+ γδ T cells may be involved in the pathogenesis of paediatric PNS by modulating the balance of Th17/Treg cells. γδ T cells may cause an imbalance in Th17/Treg cells by secreting IL-21 in the presence of IL-23.

T-cell receptor-δ expression and γδ+ T-cell infiltrates in primary cutaneous γδ T-cell lymphoma and other cutaneous T-cell lymphoproliferative disorders.

AIMS: The diagnosis of cutaneous γδ T-cell lymphoma (GDTCL) requires the identification of γδ chains of the T-cell receptor (TCR). Our aim in this study was, by using a new monoclonal antibody (mAb) against TCRδ, to evaluate TCRδ expression in formalin-fixed paraffin-embedded (FFPE) skin tissue from TCRγ+ cutaneous T-cell lymphoma (CTCL), and to assess TCRδ expression within a spectrum of other cutaneous lymphoproliferative disorders (CLPDs). METHODS AND RESULTS: Twelve cases (10 patients) with TCRγ+ CTCL and 132 additional CLPD cases (127 patients) were examined, including mycosis fungoides (MF) (n = 60), cutaneous GDTCL (n = 15), subcutaneous panniculitis-like T-cell lymphoma (SPTCL) (n = 11), and CD30+ lymphoproliferative disorder (LPD) (n = 24). Clone H-41 against TCRδ was used on a Leica Bond-3 automated stainer to label FFPE slides. H-41 immunostaining was graded as percentage infiltrate: high (50-100%), moderate (10-49%), and low (0-9%). In TCRγ+ tumours, 12 of 12 (100%) patients showed TCRδ expression comparable to TCRγ expression. No (0%) TCRγ+ cases were negative for TCRδ. In all CLPDs, TCRδ expression was as follows: GDTCL, 16 of 20 cases (14 of 15 patients) high, two moderate, and two low; MF, 0 of 60 cases high, nine moderate, and 51 low; CD30+ LPD, one of 24 cases high, two moderate, and 21 low; and SPTCL, 0 of 11 cases (0 of 9 patients) high, two moderate, and two low. Three MF-like cases and one SPTCL-like case showed high expression; the remainder showed low expression. CONCLUSIONS: mAb H-41 against TCRδ matches TCRγ in immunostaining FFPE tissues from GDTCL, supporting H-41 as a replacement for mAb γ3.20. TCRδ expression in our study suggests that the true occurrence of γδ+ non-GDTCL CTCL/CLPD may be lower than suggested by the recent literature.

Effector γδ T Cell Differentiation Relies on Master but Not Auxiliary Th Cell Transcription Factors.

γδ T lymphocytes are programmed into distinct IFN-γ-producing CD27(+) (γδ27(+)) and IL-17-producing CD27(-) (γδ27(-)) subsets that play key roles in protective or pathogenic immune responses. Although the signature cytokines are shared with their αß Th1 (for γδ27(+)) and Th17 (for γδ27(-)) cell counterparts, we dissect in this study similarities and differences in the transcriptional requirements of murine effector γδ27(+), γδ27(-)CCR6(-), and γδ27(-)CCR6(+) γδ T cell subsets and αß T cells. We found they share dependence on the master transcription factors T-bet and RORγt for IFN-γ and IL-17 production, respectively. However, Eomes is fully dispensable for IFN-γ production by γδ T cells. Furthermore, the Th17 cell auxiliary transcription factors RORα and BATF are not required for IL-17 production by γδ27(-) cell subsets. We also show that γδ27(-) (but not γδ27(+)) cells become polyfunctional upon IL-1ß plus IL-23 stimulation, cosecreting IL-17A, IL-17F, IL-22, GM-CSF, and IFN-γ. Collectively, our in vitro and in vivo data firmly establish the molecular segregation between γδ27(+) and γδ27(-) T cell subsets and provide novel insight on the nonoverlapping transcriptional networks that control the differentiation of effector γδ versus αß T cell subsets.

[Percentages of peripheral blood γδ T cells and regulatory T cells and expression of associated cytokines in infants with human cytomegalovirus infection].

OBJECTIVE: To investigate the percentages of peripheral blood γδ T cells and regulatory T cells (Treg) and the expression of associated cytokines, interleukin 17 (IL-17) and transforming growth factor-ß1 (TGF-ß1), in infants with human cytomegalovirus (HCMV) infection. METHODS: Twenty-two infants with HCMV infection (HCMV group) and 22 healthy infants who underwent physical examination (control group) were enrolled in this study. The percentages of peripheral blood γδ T cells and Treg cells were determined by flow cytometry. The levels of IL-17 and TGF-ß1 in plasma were measured using ELISA. RESULTS: Compared with the control group, the HCMV group had significantly higher percentage of γδ T cells and IL-17 level (P<0.01) and significantly lower percentage of Treg cells and TGF-ß1 level (P<0.01). In the HCMV group, the percentage of γδ T cells was negatively correlated with the percentage of Treg cells and TGF-ß1 level (P<0.05), but positively correlated with IL-17 level (P<0.05); the percentage of Treg cells was positively correlated with TGF-ß1 level (P<0.05), but negatively correlated with IL-17 level (P<0.05); there was no correlation between IL-17 level and TGF-ß1 level (P>0.05). CONCLUSIONS: There is an imbalance between γδ T cells and Treg cells in the peripheral blood of infants with HCMV infection, and γδ T cells may be involved in the secretion of IL-17.

γδ T Cells Play a Protective Role in Chikungunya Virus-Induced Disease.

UNLABELLED: Chikungunya virus (CHIKV) is an alphavirus responsible for causing epidemic outbreaks of polyarthralgia in humans. Because CHIKV is initially introduced via the skin, where γδ T cells are prevalent, we evaluated the response of these cells to CHIKV infection. CHIKV infection led to a significant increase in γδ T cells in the infected foot and draining lymph node that was associated with the production of proinflammatory cytokines and chemokines in C57BL/6J mice. γδ T cell(-/-) mice demonstrated exacerbated CHIKV disease characterized by less weight gain and greater foot swelling than occurred in wild-type mice, as well as a transient increase in monocytes and altered cytokine/chemokine expression in the foot. Histologically, γδ T cell(-/-) mice had increased inflammation-mediated oxidative damage in the ipsilateral foot and ankle joint compared to wild-type mice which was independent of differences in CHIKV replication. These results suggest that γδ T cells play a protective role in limiting the CHIKV-induced inflammatory response and subsequent tissue and joint damage. IMPORTANCE: Recent epidemics, including the 2004 to 2007 outbreak and the spread of CHIKV to naive populations in the Caribbean and Central and South America with resultant cases imported into the United States, have highlighted the capacity of CHIKV to cause explosive epidemics where the virus can spread to millions of people and rapidly move into new areas. These studies identified γδ T cells as important to both recruitment of key inflammatory cell populations and dampening the tissue injury due to oxidative stress. Given the importance of these cells in the early response to CHIKV, this information may inform the development of CHIKV vaccines and therapeutics.

Bovine peripheral blood WC1+ and WC1neg γδ T lymphocytes modulate monocyte-derived macrophage effector functions during in vitro Mycobacterium avium subspecies paratuberculosis infection.

The importance of bovine γδ T lymphocytes during anti-mycobacterial immunity is recognized; however, the role of major subsets of γδ T lymphocytes (WC1+ and WC1neg) in this process remains unclear. We investigated how WC1+ and WC1neg γδ T lymphocyte subsets of calves modulate monocyte-derived macrophage (MDM) functions during Map infection in vitro. To achieve this, Map-infected or uninfected MDMs from young calves were co-cultured with autologous WC1+ or WC1neg γδ T lymphocytes. Our data indicate that WC1+ and WC1neg γδ T lymphocytes of young calves modulate effector functions of MDMs with respect to Map killing, CD11b and MHC-II expression. We observed differences in IFN-γ production and CD25 expression on γδ T lymphocyte subsets, as well as MDM expression of CD1b when in contact with WC1neg γδ T lymphocytes.

Haplo graft engineering: sculpting to a T.

In this issue of Blood, Airoldi et al find that γδ T cells can provide critical antiviral and antileukemia effects after HLA-haploidentical hematopoietic transplants depleted of αß T cells.

γδ T-cell reconstitution after HLA-haploidentical hematopoietic transplantation depleted of TCR-αß+/CD19+ lymphocytes.

We prospectively assessed functional and phenotypic characteristics of γδ T lymphocytes up to 7 months after HLA-haploidentical hematopoietic stem cell transplantation (haplo-HSCT) depleted of αß(+) T cells and CD19(+) B cells in 27 children with either malignant or nonmalignant disorders. We demonstrate that (1) γδ T cells are the predominant T-cell population in patients during the first weeks after transplantation, being mainly, albeit not only, derived from cells infused with the graft and expanding in vivo; (2) central-memory cells predominated very early posttransplantation for both Vδ1 and Vδ2 subsets; (3) Vδ1 cells are specifically expanded in patients experiencing cytomegalovirus reactivation and are more cytotoxic compared with those of children who did not experience reactivation; (4) these subsets display a cytotoxic phenotype and degranulate when challenged with primary acute myeloid and lymphoid leukemia blasts; and (5) Vδ2 cells are expanded in vitro after exposure to zoledronic acid (ZOL) and efficiently lyse primary lymphoid and myeloid blasts. This is the first detailed characterization of γδ T cells emerging in peripheral blood of children after CD19(+) B-cell and αß(+) T-cell-depleted haplo-HSCT. Our results can be instrumental to the development of clinical trials using ZOL for improving γδ T-cell killing capacity against leukemia cells. This trial was registered at www.clinicaltrials.gov as #NCT01810120.

Phenotypic characterization and prognostic impact of circulating γδ and αß T-cells in metastatic malignant melanoma.

Human T cells carrying γδ T-cell receptors (TCRs) represent a minor population relative to those with αß TCRs. There has been much interest recently in the possibility of using these γδ T-cells in cancer therapy because they can kill tumor cells in vitro in an MHC-unrestricted manner, and possess potential regulatory capability and antigen-presenting capacity. The presence of γδ T-cells in late-stage melanoma patients and their relationship with survival has not been extensively explored, although relatively lower percentages of total γδ T-cells and Vδ2+ cells have been reported. Here, we present a detailed analysis of associations of γδ T-cell subsets and differentiation stages with survival in Stage IV patients, compared with CD4+ and CD8+ αß T-cells. We found an increased Vδ1:Vδ2-ratio and a decreased CD4:CD8-ratio in patients compared to healthy controls, on the basis both of relative frequencies and absolute cell counts per µL blood. Nonetheless, Kaplan-Meier analyses showed that a higher than median frequency of Vδ1+ cells was negatively associated with survival, whereas there were no positive or negative associations with frequencies of Vδ2+ cells. Correlations of cell differentiation status with survival revealed a negative association of early-differentiated Vδ1+ T cells with survival, both on the basis of relative frequencies and absolute counts. There was also a positive correlation between the frequencies of early-differentiated CD8+ αß T-cells and survival. Our findings suggest peripheral blood frequencies of Vδ1+ T-cells as a potential prognostic marker in melanoma. The mechanisms by which higher abundance of Vδ1+ cells are associated with poorer survival require determination.

Id3 and Id2 act as a dual safety mechanism in regulating the development and population size of innate-like γδ T cells.

The innate-like T cells expressing Vγ1.1 and Vδ6.3 represent a unique T cell lineage sharing features with both the γδ T and the invariant NKT cells. The population size of Vγ1.1(+)Vδ6.3(+) T cells is tightly controlled and usually contributes to a very small proportion of thymic output, but the underlying mechanism remains enigmatic. Deletion of Id3, an inhibitor of E protein transcription factors, can induce an expansion of the Vγ1.1(+)Vδ6.3(+) T cell population. This phenotype is much stronger on the C57BL/6 background than on the 129/sv background. Using quantitative trait linkage analysis, we identified Id2, a homolog of Id3, to be the major modifier of Id3 in limiting Vγ1.1(+)Vδ6.3(+) T cell expansion. The Vγ1.1(+)Vδ6.3(+) phenotype is attributed to an intrinsic weakness of Id2 transcription from Id2 C57BL/6 allele, leading to an overall reduced dosage of Id proteins. However, complete removal of both Id2 and Id3 genes in developing T cells suppressed the expansion of Vγ1.1(+)Vδ6.3(+) T cells because of decreased proliferation and increased cell death. We showed that conditional knockout of Id2 alone is sufficient to promote a moderate expansion of γδ T cells. These regulatory effects of Id2 and Id3 on Vγ1.1(+)Vδ6.3(+) T cells are mediated by titration of E protein activity, because removing one or more copies of E protein genes can restore Vγ1.1(+)Vδ6.3(+) T cell expansion in Id2 and Id3 double conditional knockout mice. Our data indicated that Id2 and Id3 collaboratively control survival and expansion of the γδ lineage through modulating a proper threshold of E proteins.

Primary Cutaneous T-cell Lymphoma With Coexpression of T-Cell Receptors αß and γδ.

T lymphocytes belong to 2 distinct sublineages that express either αß or γδ T-cell receptor (TCR) complex. Although malignancy is a great instigator of lineage infidelity, as exemplified by aberrant expression of numerous lineage markers in lymphoma cells, malignant T cells rarely coexpress αß and γδ TCR complexes. Similarly, only rare cases of CD4/CD8 double-positive primary cutaneous T-cell lymphoma have been reported. In this report, we describe a remarkable case of primary cutaneous T-cell lymphoma coexpressing αß and γδ TCR complexes, strong diffuse CD8, and a very restricted coexpression of CD4 and CD8. A 66-year-old man was referred to our center for treatment of a persistent eczematoid eruption of 6 years of duration. An initial biopsy demonstrated not only marked spongiosis, but also an epidermotropic population of CD4 small mature T cells with partial expression of CD8. The process remained indolent for another year, followed by an abrupt progression with development of plaques and tumors. Repeat biopsies of these lesions demonstrated a superimposed population of large anaplastic T cells extensively involving the dermis and epidermis. The large cells showed a strong uniform expression of CD3, CD8, CD45RA, CD5, granzyme, TIA1, perforin, TCR-ß, and TCR-γ and a weaker but unambiguous expression of CD4, CD25, CD2, and CD56. TCR gene rearrangement studies showed clonal rearrangements for TCR-ß and TCR-γ with identical peaks to those seen in the biopsy from a year earlier. The patient developed lymphadenopathy, with a biopsy showing nodal involvement by a morphologically and phenotypically identical neoplastic T-cell population. The disease showed partial response to systemic chemotherapy with development of new plaques, but these new lesions have regressed with radiation therapy.

Primary Cutaneous Gamma-Delta (γ/δ) T-cell Lymphoma: An Unusual Case With Very Subtle Histopathological Findings.

Primary cutaneous γ/δ T-cell lymphoma (PCGDTCL) accounts for <1% of all primary cutaneous lymphomas. These rare diseases are believed to originate from γ/δ lymphocytes. Clinical presentation may vary, but its clinical behavior is regarded as aggressive and long-term survival is anecdotal. This study describes the case of a 60-year-old man with multiple, rapidly progressing skin plaques on his head, arms, torso, buttocks, and legs. The histopathological changes seen in the skin biopsy were extraordinarily subtle with mild epidermal hyperplasia and a very sparse lymphoid infiltrate involving epidermis and superficial dermis. Immunohistochemical studies revealed the atypical intraepidermal hyperchromatic cells to be mostly positive for CD3 and CD7 and negative for both CD4 and CD8. The intraepidermal atypical lymphocytes were positive for TCR gamma, and negative for betaF1 and CD56. The clinical, morphologic, and immunohistochemical findings supported the diagnosis of PCGDTCL. This case illustrates a case of epidermotropic variant of PCGDTCL that, albeit a bland histopathological presentation, was associated with an aggressive clinical behavior.

Phenotypic Variation in Different Lesions of Mycosis Fungoides Biopsied Within a Short Period of Time From the Same Patient.

Phenotypic variants of mycosis fungoides (MF) include mainly the expression of cytotoxic markers by neoplastic cells (either α/ß or γ/δ cytotoxic). To manage the patient properly, distinction from other cutaneous cytotoxic natural killer/T-cell lymphomas is paramount. Particularly for cutaneous γ/δ T-cell lymphoma, distinction is often based on clinicopathologic correlation (presence of tumors at first diagnosis as opposed to patches only in MF). The authors report a case of cytotoxic MF characterized by expression of TCRγ in two of three biopsies performed within a time frame of 1 week. The patient presented with patches, plaques, and 1 tumor at the time of first diagnosis; thus, distinction from cutaneous γ/δ T-cell lymphoma was not possible on clinical grounds alone. The diagnosis of MF was established, thanks to the phenotypic variations revealed by the three biopsies, with 1 lacking expression of cytotoxic proteins (TIA-1 and granzyme B) and of TCRγ. This case shows the importance to perform several biopsies in cases of cutaneous lymphoma, as morphologic and phenotypic features are variable and information gathered from a single biopsy may result in a wrong diagnosis.

Antigen-specific regulation of IgE antibodies by non-antigen-specific γδ T cells.

We re-examined the observation that γδ T cells, when transferred from mice tolerized to an inhaled conventional Ag, suppress the allergic IgE response to this Ag specifically. Using OVA and hen egg lysozyme in crisscross fashion, we confirmed the Ag-specific IgE-regulatory effect of the γδ T cells. Although only Vγ4(+) γδ T cells are regulators, the Ag specificity does not stem from specificity of their γδ TCRs. Instead, the Vγ4(+) γδ T cells failed to respond to either Ag, but rapidly acquired Ag-specific regulatory function in vivo following i.v. injection of non-T cells derived from the spleen of Ag-tolerized mice. This correlated with their in vivo Ag acquisition from i.v. injected Ag-loaded splenic non-T cells, and in vivo transfer of membrane label provided evidence for direct contact between the injected splenic non-T cells and the Vγ4(+) γδ T cells. Together, our data suggest that Ag itself, when acquired by γδ T cells, directs the specificity of their IgE suppression.

Repeated systemic administrations of both aminobisphosphonates and human Vγ9Vδ2 T cells efficiently control tumor development in vivo.

Peripheral Vγ9Vδ2 T lymphocytes compose a major γδ T cell subset in primates with broad reactivity against tumor cells. Vγ9Vδ2 T cells are specifically activated by phosphorylated isoprenoid pathway metabolites called "phosphoagonists." Accordingly, pharmacologic inhibitors of the mevalonate pathway, such as aminobisphosphonates (NBP) that upregulate the intracellular production of phosphoagonists, increase antitumor Vγ9Vδ2 T cell responses. Immunotherapeutic protocols exploiting GMP-grade agonist molecules targeting human Vγ9Vδ2 T lymphocytes have yielded promising, yet limited, signs of antitumor efficacy and therefore need to be improved for next-generation immunotherapies. In this study, we used a model of s.c. human tumor xenografts in severely immunodeficient mice to assess the antitumor efficacy of systemic NBP treatments when combined with the adoptive transfer of human Vγ9Vδ2 T cells. We show that infusion of Vγ9Vδ2 T cells, 24 h after systemic NBP treatment, efficiently delays tumor growth in mice. Importantly, our results indicate efficient but transient in vivo NBP-induced sensitization of tumor cells to human Vγ9Vδ2-T cell recognition. Accordingly, repeated and combined administrations of both NBP and γδ T cells yielded improved antitumor responses in vivo. Because Vγ9Vδ2 T cells show similar responsiveness toward both autologous and allogeneic tumors and are devoid of alloreactivity, these results provide preclinical proof of concept for optimized antitumor immunotherapies combining NBP treatment and adoptive transfer of allogeneic human γδ T cells.