Prostaglandin E2 amplifies IL-17 production by γδ T cells during barrier inflammation.

Interleukin-17 (IL-17)-producing γδ (γδ17) T cells are innate-like lymphocytes that contribute to protective anti-microbial responses but are also implicated in pathogenic inflammation at barrier sites. Understanding tissue-specific signals that regulate this subset is important to boost host defense mechanisms, but also to mitigate immunopathology. Here, we demonstrate that prostaglandin E2 (PGE2), a cyclooxygenase-dependent member of the eicosanoid family, directly enhances cytokine production by circulating and tissue-specific γδ17 T cells in vitro. Gain- and loss-of-function in vivo approaches further reveal that although provision of PGE2 amplifies psoriasiform inflammation, ablation of host mPGES1-dependent PGE2 synthesis is dispensable for cutaneous γδ17 T cell activation. By contrast, loss of endogenous PGE2 production or depletion of the gut microbiota compromises intestinal γδ17 T cell responses and increases disease severity during experimental colitis. Together, our results demonstrate how a lipid mediator can synergize with tissue-specific signals to enhance innate lymphocyte production of IL-17 during barrier inflammation.

Alpaca (Vicugna pacos), the first nonprimate species with a phosphoantigen-reactive Vγ9Vδ2 T cell subset.

Vγ9Vδ2 T cells are a major γδ T cell population in the human blood expressing a characteristic Vγ9JP rearrangement paired with Vδ2. This cell subset is activated in a TCR-dependent and MHC-unrestricted fashion by so-called phosphoantigens (PAgs). PAgs can be microbial [(E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate, HMBPP] or endogenous (isopentenyl pyrophosphate, IPP) and PAg sensing depends on the expression of B7-like butyrophilin (BTN3A, CD277) molecules. IPP increases in some transformed or aminobisphosphonate-treated cells, rendering those cells a target for Vγ9Vδ2 T cells in immunotherapy. Yet, functional Vγ9Vδ2 T cells have only been described in humans and higher primates. Using a genome-based study, we showed in silico translatable genes encoding Vγ9, Vδ2, and BTN3 in a few nonprimate mammalian species. Here, with the help of new monoclonal antibodies, we directly identified a T cell population in the alpaca (Vicugna pacos), which responds to PAgs in a BTN3-dependent fashion and shows typical TRGV9- and TRDV2-like rearrangements. T cell receptor (TCR) transductants and BTN3-deficient human 293T cells reconstituted with alpaca or human BTN3 or alpaca/human BTN3 chimeras showed that alpaca Vγ9Vδ2 TCRs recognize PAg in the context of human and alpaca BTN3. Furthermore, alpaca BTN3 mediates PAg recognition much better than human BTN3A1 alone and this improved functionality mapped to the transmembrane/cytoplasmic part of alpaca BTN3. In summary, we found remarkable similarities but also instructive differences of PAg-recognition by human and alpaca, which help in better understanding the molecular mechanisms controlling the activation of this prominent population of γδ T cells.

Chlorpyrifos induces redox imbalance-dependent inflammation in common carp lymphocyte through dysfunction of T-cell receptor γ.

Chlorpyrifos is a poisonous pesticide that is highly toxic to fish and aquatic organisms. However, there are fewer reports about how chlorpyrifos influences the redox balance of immune cells. Herein, the head kidney tissue treated with chlorpyrifos to do transcriptome analysis and TCR γ was screened out. Subsequently, we established TCR γ knockdown and overexpression carp head kidney lymphocyte models, respectively, by using RNA interference and pcDNA3.1. Real-time PCR, fluorescent staining, oxidation and antioxidant kit were used to detect the related factors. We found that TCR γ knockdown significantly increased the mRNA expression of HSP70 and HSP90 and decreased the mRNA expression of SOD and CAT. Meanwhile, TCR γ knockdown reduced the activities of GSH, GSG-PX, T-AOC, CAT and SOD and increased the content of MDA and H2 O2 and activities of iNOS. Adverse results were obtained in TCR γ overexpression group. Additionally, TCR γ knockdown significantly increased the mRNA expression of IFN-γ, IL-1ß, IL-8, IL-10, Nrf2 and NF-κB, but relieved TCR γ overexpression, in which the process of inflammation was activated. Our results reported here indicated that chlorpyrifos induces redox imbalance-dependent inflammation in common carp lymphocyte through dysfunction of T-cell receptor γ, and HSPs play potential protective role in entire process.

In vivo expansion and activation of γδ T cells as immunotherapy for refractory neuroblastoma: A phase 1 study.

INTRODUCTION: CD3+ γδ+ T cells comprise 2% to 5% of circulating T cells with Vγ9Vδ2+ cells the dominant circulating subtype. Vγ9Vδ2+ cells recognize non-peptide phosphoantigens and stress-associated NKG2D ligands expressed on malignant cells. Strategies that incorporate the tumoricidal properties of γδ T cells represent a promising immunotherapeutic strategy for treatment of solid malignancies including neuroblastoma (NB). In this prospective, non-randomized Phase I trial, we assessed whether circulating Vγ9Vδ2+ cells could be safely expanded using intravenous ZOL (Zoledronate [Zometa]) and subcutaneous Interleukin-2 (IL-2) in patients with refractory NB. METHODS: Patients 2 to 21 years of age with refractory neuroblastoma with no known curative therapeutic options received ZOL on day 1, and IL-2 on days 1 to 5 and 15 to 19 of each 28-day cycle (n = 4). Lymphocyte immunophenotyping was assessed weekly. Immunophenotyping studies from the treatment group were compared with healthy pediatric controls (n = 16; range, 5y-15y) and of untreated NB disease controls (n = 9; range, 4m-18y). RESULTS: Treatment was well tolerated with no unexpected grade 3 and 4 toxicities. Lymphocyte subset counts did not differ significantly between volunteers and disease controls with the exception of γδ+ T cell counts that were significantly higher in healthy volunteers (212 + 93 vs. 89 + 42, P = 0.05). Study patients showed increases in circulating γδ+ T cell count (3-10 fold) after the first week, increasing into the range seen in healthy volunteers (125 + 37, P = 0.1940). Interestingly, all ZOL + IL-2 treated patients showed significant increases in CD3+CD4+CD27CD127 T cells that rose weekly in 2 patients throughout the 4 weeks of observation (maximum 41% and 24% of total CD3+CD4+ T cells, respectively). CONCLUSIONS: In summary, combined ZOL and IL-2 is well tolerated and restored γδ+ T cell counts to the normal range with a moderate expansion of Natural Killer cells. Progressive increases in circulating CD4+ T cells with a regulatory phenotype cells may offset beneficial effects of this therapy.

γδ Intraepithelial Lymphocyte Migration Limits Transepithelial Pathogen Invasion and Systemic Disease in Mice.

BACKGROUND & AIMS: Intraepithelial lymphocytes that express the γδ T-cell receptor (γδ IELs) limit pathogen translocation across the intestinal epithelium by unknown mechanisms. We investigated whether γδ IEL migration and interaction with epithelial cells promote mucosal barrier maintenance during enteric infection. METHODS: Salmonella typhimurium or Toxoplasma gondii were administered to knockout (KO) mice lacking either the T cell receptor δ chain (Tcrd) or CD103, or control TcrdEGFP C57BL/6 reporter mice. Intravital microscopy was used to visualize migration of green fluorescent protein (GFP)-tagged γδ T cells within the small intestinal mucosa of mice infected with DsRed-labeled S typhimurium. Mixed bone marrow chimeras were generated to assess the effects of γδ IEL migration on early pathogen invasion and chronic systemic infection. RESULTS: Morphometric analyses of intravital video microscopy data showed that γδ IELs rapidly localized to and remained near epithelial cells in direct contact with bacteria. Within 1 hour, greater numbers of T gondii or S typhimurium were present within mucosae of mice with migration-defective occludin KO γδ T cells, compared with controls. Pathogen invasion in Tcrd KO mice was quantitatively similar to that in mice with occludin-deficient γδ T cells, whereas invasion in CD103 KO mice, which have increased migration of γδ T cells into the lateral intercellular space, was reduced by 63%. Consistent with a role of γδ T-cell migration in early host defense, systemic salmonellosis developed more rapidly and with greater severity in mice with occludin-deficient γδ IELs, relative to those with wild-type or CD103 KO γδ IELs. CONCLUSIONS: In mice, intraepithelial migration to epithelial cells in contact with pathogens is essential to γδ IEL surveillance and immediate host defense. γδ IEL occludin is required for early surveillance that limits systemic disease.

Rapamycin together with TGF-ß1, IL-2 and IL-15 induces the generation of functional regulatory γδT cells from human peripheral blood mononuclear cells.

Regulatory γδT cell (γδTreg) is a recently reported subset of γδT cells characterized by both expressions of TCRγδ and Foxp3, with potential immunosuppressive functions. However, the further studies of γδTreg are limited mainly due to its low quantities in vivo and the lack of methods to induce γδTreg largely in vitro. Here we show that rapamycin together with TGF-ß1, IL-2 and IL-15 can induce and expand γδTregs derived from human peripheral blood mononuclear cells efficiently in vitro. Thus-induced γδTregs express high levels of Foxp3 and CD25, and display significant immunosuppressive activities in vitro.

The γδ T-cell receptor repertoire is reconstituted in HIV patients after prolonged antiretroviral therapy.

OBJECTIVE: Determine whether reconstitution of Vγ2Vδ2 T cells in patients with HIV is due to new cell synthesis with recovery of the T-cell receptor repertoire or proliferative expansion of residual cells from the time of treatment initiation. DESIGN: Perform a cross-sectional analysis of the T-cell receptor complexity of Vγ2 chain in patients treated for HIV, natural virus suppressors who control viremia to undetectable levels, patients with chronic low-level viremia in the absence of therapy, and uninfected controls. Apply quantitative methods for repertoire analysis to assess the degree of Vδ2 repertoire loss or reconstitution. METHODS: T-cell receptor Vγ2 chain DNA clones (up to 300 per patient sample) were sequenced and aligned to enumerate the antigen-reactive subset with Vγ2-Jγ1.2 rearrangements. Predominant shared (public) sequences in each patient were compared to a reference library of public sequences from uninfected controls to assess the extent of similarity. Repertoire comparisons were quantified through bioinformatics testing. RESULTS: Patients with prolonged virus suppression due to antiretroviral therapy reconstituted the Vγ2 T-cell repertoire to near-normal levels. Natural virus suppressors were similar to the treatment group. Severe defects in the Vγ2 T-cell receptor repertoire were observed in patients with chronic viremia despite the absence of overt disease. CONCLUSION: Prolonged HIV suppression with antiretroviral therapy leads to reconstitution of the Vγ2Vδ2 T-cell subset deleted in HIV disease. Direct evidence for repair of the T-cell receptor repertoire supports a view that treatment-associated immune reconstitution is due to new cell synthesis and not to expansion of residual cell populations.

Can peripheral blood γδ T cells predict osteonecrosis of the jaw? An immunological perspective on the adverse drug effects of aminobisphosphonate therapy.

Nitrogen-bisphosphonates (n-BP), often referred to as aminobisphosphonates, are the most commonly prescribed drugs for the treatment of disorders of bone fragility. However, long-term continuous treatment predisposes certain individuals to serious rare side effects, such as bisphosphonate-associated osteonecrosis of the jaw (BAONJ). n-BP use is known to unintentionally activate a subset of innate T cells called Vγ9Vδ2 T cells, but the consequence of this chronic immune stimulation has remained unexplored. The primary objectives of this study were to 1) determine the fate of Vγ9Vδ2 T cells in osteoporotic patients on n-BP therapy as a function of time and type of therapy; 2) evaluate the proportion of Vγ9Vδ2 T cells in patients who had recently experienced n-BP-associated ONJ. We found there is a notable loss of Vγ9Vδ2 T cells over time in osteoporotic patients on n-BP therapy, particularly those on intravenous (iv) therapy (Spearman r = -0.55, p < 0.0001 iv; r = -0.3, p < 0.03 oral) (n = 68); no difference was observed in total T cells, monocytes, or granulocytes. Importantly, the observed negative effect on Vγ9Vδ2 T cells coincides with the reported route of administration and timing of the rare occurrence of BAONJ. Patients (n = 6) who had experienced BAONJ were all found to be significantly deficient in Vγ9Vδ2 T cells (median = 0.07%) in comparison to age- and sex-matched treatment-naïve controls (N = 11; median = 2.40%), U = 0, p = 0.001; this was the only consistent difference in the leukocytes assessed. All BAONJ cases had an underlying condition that further contributed to impaired immunity. We propose Vγ9Vδ2 T cells show a strong potential to serve as harbingers of possible adverse immune effects of n-BP therapy, particularly in those patients already having a compromised immune system as they may be most vulnerable to the development of conditions such as BAONJ.

CCR6 is required for epidermal trafficking of γδ-T cells in an IL-23-induced model of psoriasiform dermatitis.

A subset of CC chemokine receptor-6(+) (CCR6(+)), γδ-low (GDL) T cells that express Th17 cytokines in mouse skin participates in IL-23-induced psoriasiform dermatitis. We use CCR6-deficient (knockout, KO) and wild-type (WT) mice to analyze skin trafficking patterns of GDL T cells and function-blocking mAbs to determine the role of CCR6 in IL-23-mediated dermatitis. Herein, CCL20 was highly upregulated in IL-23-injected WT mouse ear skin as early as 24 hours after initial treatment, and large numbers of CCR6(+) cells were observed in the epidermis of IL-23-injected WT mice. Anti-CCL20 mAbs reduced psoriasiform dermatitis and blocked recruitment of GDL T cells to the epidermis. In CCR6 KO mice, GDL T cells failed to accumulate in the epidermis after IL-23 treatment, but the total numbers of GDL T cells in the dermis of WT and CCR6 KO mice were equivalent. There was an ∼70% reduction in the proportion of IL-22(+) GDL T cells in the dermis of CCR6 KO mice (vs WT mice), suggesting that effector function and epidermal recruitment of GDL T cells are impaired in CCR6-deficient mice. Thus, these data show that CCR6 regulates epidermal trafficking of γδ-T-cell subsets in the skin and suggest the potential of CCR6 as a therapeutic target for psoriasis.

Tumor-promoting versus tumor-antagonizing roles of γδ T cells in cancer immunotherapy: results from a prospective phase I/II trial.

Emerging evidence suggests that nitrogen-containing bisphosphonates have direct and indirect anticancer effects including immunomodulatory effects. Using in vivo targeting of bisphosphonate-reactive γδ T cells by adding low-dose interleukin-2 to zoledronic acid, we evaluated the safety, pharmacodynamics, and antitumor activity of this immunotherapy approach in 21 adults with advanced malignancies (renal cell carcinoma [RCC], malignant melanoma, and acute myeloid leukemia). A total of 58 treatment cycles were administered and the median number of treatment cycles was 2.7 (range, 1 to 6). The regimen was well tolerated, with no grade 3 to 4 drug-related adverse events, except for fever. No objective responses were observed in both cohorts of solid tumors (RCC and malignant melanoma), whereas 2 patients with acute myeloid leukemia (25%) achieved objective tumor responses (partial remission). Pharmacodynamic analyses showed significant in vivo activation (interferon-γ production) and expansion of γδ T cells in all evaluable patients. High pretreatment serum vascular endothelial growth factor (VEGF) levels and an unexpected increase in VEGF induced by zoledronic acid plus low-dose interleukin-2 were correlated with the lack of a clinical response. In conclusion, this study indicates that immunotherapy-induced VEGF can limit clinical innate tumor immune responses, especially for angiogenesis-dependent solid tumors. Our data challenge the current cellular immunotherapy paradigms in the treatment of cancer.

Flow cytometric analysis of age-related changes in intestine intraepithelial lymphocyte subsets and their functional preservation after feeding mice on spirulina.

We investigated age-related changes in intestinal intraepithelial lymphocyte (IEL) subsets in mice by flow cytometric analysis and their functional preservation as affected by feeding Spirulina, a cyanobacterium that is known to possess various therapeutic effects, including immune modulation activity. The number of cells possessing the leukocyte-common antigen CD45(+) cells in mice (43 weeks old) of the aged group, used as a representative marker for IELs, was significantly lower than that of adult mice (5 weeks old). Either the proportion or the number of CD45(+)CD8(+) cells of the aged mice was significantly lower than that of adult mice, corresponding to previous reports. Proportions and numbers of CD4(+)CD8(+) cells in aged mice, on the other hand, were higher than those in adult mice. Increased or decreased levels of the cell surface antigens observed in the aged mice tended to be restored in aged mice fed Spirulina (aged-SP group), which ingested a hot water extract of Spirulina (SpHW). In fact, the proportions of CD45(+)CD8(+) cells and CD45(+)TCRgammadelta(+) cells in the aged-SP group significantly increased in comparison to the control aged group, which ingested ordinary chow and water ad libitum. These results suggest that ingestion of SpHW in the aged-SP group may contribute to the functional preservation of the intestinal epithelium as a first line of mucosal barrier against infectious agents through retaining the number of certain IELs. Changes in the number of other IEL subsets and blood cells are also discussed.

Grape consumption supports immunity in animals and humans.

All nutrients play a role in maintaining the immune system and providing substrate for the response. gammadelta T cells, on the other hand, seem to have a unique response to certain dietary bioactive components found in the plant family. Although the identification of those components is not well known yet, members of the proanthocyanidin family and the anthocyanin family of compounds are candidates. Because grapes and grape products contain both of these types of compounds, I hypothesized that grapes may help maintain or support the immune response, specifically the gammadelta T cell. Data from intact animal studies show that immune function is supported by grape products. In humans, relatively little research has been conducted using the food as an intervention; however, a study currently in progress showed that Concord grape juice supported circulating gammadelta T cells and maintained immune function, whereas participants receiving the placebo juice had changes associated with reduced immunity. After an overview of immunity, this paper will focus on reviewing the literature on grapes and other food products made from grapes and their potential for interaction with the gammadelta T cell in whole-body systems.

Comparison of phenotype of gammadelta T cells generated using various cultivation methods.

It has been demonstrated, that gammadelta T cells play an important role in the development of immune responses to many pathogens. gammadelta T cells play a role in the clearance of viral and microbiological infections, anti-tumor responses, but also in autoimmune diseases. Many different protocols for the isolation and cultivation of gammadelta T cells can be found in the literature. Here we compare three common cultivation protocols for gammadelta T cells derived from peripheral blood with a newly developed protocol depending on SLAM (Signaling Lymphocyte Activation Molecule) stimulation. We demonstrate that the cultivation protocol chosen to raise gammadelta T cells has direct impact on the resulting gammadelta T cell phenotype. We show differences in gammadelta TCR composition, memory phenotype formation, CD8 receptor expression and the expression of NK cell markers depending on the stimulation protocol used. As such, the cultivation protocol chosen for a series of experiments might have significant impact on the outcome of the experiments and should be considered carefully.

Thiopyrophosphoantigens: solid-phase synthesis and in vitro characterization of a new class of Vgamma9 Vdelta2 T cells activators.

The Vgamma9 Vdelta2 T cells mediate rapid, innate-like immune responses to pathogens and are important in several key immunoregulatory pathways, including those involved in infections and tumor development. Vgamma9 Vdelta2 T cells respond to low molecular weight isoprenoid phosphoantigens; the prototypic stimulatory compound is isopentenylpyrophosphate (IPP), an alkylphosphate intermediate of mevalonate metabolism that elicits proliferative, cytotoxic, and cytokine secretion responses. We studied the replacement of the pyrophosphate moiety with the thiopyrophosphate bioisostere, synthesizing thioanalogues of IPP and 4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP, the most potent natural antigen known to date). Once their in vitro efficacy and stability had been demonstrated, we synthesized a small library of compounds through the development of an innovative solid-phase strategy. Biological results confirmed thioHMBPP to be the best compound of this first series. Future aims are (i) the exploitation of the parallel solid-phase strategy to further explore structure-activity relationships of this new class of synthetic antigens and (ii) the determination of the PK/PD profile of thioHMBPP.

Activated human gammadelta T cells as stimulators of specific CD8+ T-cell responses to subdominant Epstein Barr virus epitopes: potential for immunotherapy of cancer.

The efficacy of current cancer vaccines is limited by the functional heterogeneity and poor availability and expansion of professional antigen-presenting cells (APCs). Besides their potent innate effector properties, gammadelta T cells have been suggested to be involved in the initiation and maintenance of adaptive immune responses. Here, we investigated the capacity of human gammadelta T cells to induce expansion of virus-specific T cells to Epstein Barr virus (EBV) antigens. Aminobisphosphonate-stimulated human peripheral blood-derived gammadelta T cells (Vgamma2+Vdelta2+) acquired a dual phenotype characteristic for both APCs and effector memory T cells. Coincubation of activated gammadelta T cells pulsed with human leukocyte antigen-restricted epitopes of either the highly stimulatory EBV lytic cycle antigen Bam H1 Z fragment leftward open reading frame or the tumor-associated latent EBV antigen latent membrane protein 2a (LMP2a) with autologous peripheral blood lymphocytes induced selective expansion of peptide-specific, fully functional CD3CD8 cytolytic effector memory T cells. Furthermore, gammadelta T APCs efficiently processed and presented endogenous antigen, as demonstrated by the capacity of LMP2a gene-transduced gammadelta T cells to induce expansion of T cells with broad specificity for various LMP2a peptides. The capacity of autologous gammadelta T cells to induce LMP2a-specific autologous cytotoxic T lymphocytes was confirmed in 2 patients with Hodgkin lymphoma. In summary, bisphosphonate-activated human gammadelta T cells stimulate expansion of cytotoxic effector T cells specific for both subdominant and dominant viral epitopes and thus show promise as a novel source of efficient APCs for immunotherapy of viral and malignant disease.

Requirement of L-selectin for gammadelta T lymphocyte activation and migration during allergic pleurisy: co-relation with eosinophil accumulation.

Intra-thoracic antigenic challenge (ovalbumin, 12.5 microg/cavity) led to increased numbers of gammadelta T lymphocytes in pleural cavities, blood and thoracic lymph nodes in sensitized mice within 48 h. Part of these cells expressed CD62L, which increased on gammadelta T cell surfaces obtained from lymph nodes after ovalbumin (OVA) challenge. Selectin blockade by fucoidan pre-treatment (10 mg/kg, i.v.) impaired in vivo increase in CD25(+) and c-fos(+) gammadelta T cell numbers in lymph nodes, indicating a role for selectins on gammadelta T lymphocyte activation and proliferation. In vivo selectin blockade by fucoidan or alpha-CD62L mAb (200 microg/mice, i.p.) also inhibited OVA-induced gammadelta T cell accumulation in pleural cavities. Confirming the direct effect of CD62L on gammadelta T cell transmigration, the migration of i.v. adoptively-transferred CFSE-labeled gammadelta T lymphocytes into pleural cavities of challenged recipient mice was impaired by fucoidan ex vivo treatment. It is noteworthy that eosinophil influx was also impaired in those mice, indicating that reduced eosinophil migration by CD62L in vivo blockade depended on gammadelta T cell migration via CD62L molecules. Accordingly, pleural gammadelta T lymphocytes from fucoidan-treated mice presented reduced OVA-induced IL-5 and CCL11 production. Supporting these data, the depletion of Vgamma4 T lymphocytes, which are pulmonary gammadelta T cells, decreased OVA-induced eosinophil influx into allergic site. Such results demonstrate that CD62L is crucial for the activation of gammadelta T cells in lymph nodes, for their migration into inflamed tissue and for the modulation of eosinophil influx during allergic response.

Aminobisphosphonates as new weapons for gammadelta T Cell-based immunotherapy of cancer.

Several observations in mice and in humans have collectively laid the foundation for examining the potential of gammadelta T cells to exert tumor immunotherapy. Human gammaDelta T cells can be activated in a non-MHC dependent fashion either by low molecular mass phosphoantigens, or by agents that provoke the accumulation of endogenous pyrophosphates such as isopentenylpyrophosphate. Among the latter, aminobisphosphonates are well-established in the clinic, and extensive data are available on the compounds' antiangiogenic, antiosteolytic and pro-apoptotic properties. In this review we discuss on the possibility that the intentional activation of gammadelta T cells in vivo by aminobisphosphonates may represent a promising target for the design of novel and highly innovative immunotherapy in patients with different types of cancer.

Gamma-delta T-cell-mediated dilated cardiomyopathy.

Gamma-delta T-cells are usually minor component of peripheral blood and lymphoid tissues, but may play an important role in autoimmune diseases. We here describe the first case of dilated cardiomyopathy (DCM) with heart infiltration by mostly gamma-delta T-cells, who improved significantly by steroid therapy. In general, steroid therapy has only a little effect on DCM, however these findings might have implications with respect to the selection of patients who might respond to immunosuppressive therapy.

A lectin from Chinese mistletoe increases gammadelta T cell-mediated cytotoxicity through induction of caspase-dependent apoptosis.

In this study, a mistletoe lectin (ML) was purified from Chinese mistletoe and the effect of this 60 kDa Chinese ML on human gammadelta T cell cytotoxicity, apoptosis and modulation of the cytokine network was studied. The cytotoxic properties of delta T cells was evaluated by using a (51)Cr release test and employed fluorescence-activated cell sorting and enzyme-linked immunosorbent assay analysis to quantify translocation of the cell membrane phospholipid, phosphatidylserine and nuclear DNA fragmentation during apoptosis. It was found that: (i) ML effectively stimulated gammadelta T cell proliferation in a dose- and time-dependent manner; (ii) ML increased gammadelta T cell cytotoxicity; (iii) ML could modulate lipopolysaccharide-induced cytokine release in a pro-inflammatory manner by increasing tumor necrosis factor (TNF)-alpha release and inhibiting the release of anti-inflammatory interleukin (IL)-10; (iv) ML induced apoptosis in caspase-dependent and CD95-independent manner. The results indicated that ML is a potent immunomodulator to human gammadelta T cell cytotoxicity, apoptos is and cytokine production.