Gamma/delta T cells provide innate immunity against renal cell carcinoma

Polymorphisms of the human NRAMP1 gene are associated with response to bacillus Calmette-Guerin immunotherapy for superficial bladder cancer

PURPOSE

Superficial bladder tumors have a high recurrence rate and 10% to 20% of recurrences progress to invasive cancer. Recurrence and progression can best be prevented by nonspecific immunotherapy using intravesical BCG instillations. The NRAMP1 gene has been implicated in susceptibility to infectious and autoimmune diseases, and in response to BCG in murine models. We evaluated the association of 5 NRAMP1 gene polymorphisms with the risk of superficial bladder cancer recurrence and response to immunotherapy.

MATERIALS AND METHODS

The (GT)n, 274 C/T, 469 + 14 G/C, 1465-85 G/A and D534N polymorphisms were tested on peripheral blood DNA of individuals from three cohorts: 37 bladder tumor patients treated by transurethral resection and without recurrence after up to eight years, 67 patients at high risk of recurrence of their bladder tumors and treated with BCG and 109 controls, using restriction fragment length polymorphisms or microsatellite analysis following PCR amplification.

RESULTS

The D543N G:A genotype was found more frequently in patients at high risk of recurrence (8 of 67 or 12%) than in controls (2 of 109 or 2%) (p = 0.007). Patients with nonrecurrent tumors showed no difference with controls (1 of 37 or 3%) (p = 1.0). Moreover, in multivariate and survival analyses, both D543N and (GT)n polymorphisms showed association with recurrence-free survival in the cohort of patients at high risk of recurrence, following BCG treatment.

CONCLUSIONS

These data suggest the implication of the NRAMP1 gene in bladder cancer recurrence and response to BCG immunotherapy.

The association between malignant melanoma and noncutaneous malignancies

BACKGROUND

Both increases and decreases in the incidence of subsequent malignancies in melanoma patients have been reported. We examined the database of the Indiana University Cancer Center to determine whether there is an association between malignant melanoma and noncutaneous malignancies.

OBJECTIVE

We searched for evidence of noncutaneous malignancies in a cohort of melanoma patients.

METHODS

Patients with microscopically confirmed malignant melanoma diagnosed between January 1987 and March 2001 were analyzed. This cohort was investigated for noncutaneous malignancies occurring either before or after the diagnosis of melanoma. The standardized incidence ratios (SIR) were calculated as the ratio of the observed to the expected number of patients with second malignancies, and 95% confidence intervals (95% CI) around the SIR were estimated from the cumulative Poisson distribution.

RESULTS

A total of 955 patients with melanoma (498 males and 457 females) were documented over the 14-year period. Sixty-nine noncutaneous malignancies were identified in 59 (6.2%) melanoma patients (39 males and 20 females). There was a higher risk of non-Hodgkin's lymphoma (SIR = 1.91; 95% CI, 0.88-3.62) in men and renal cell carcinoma (SIR = 2.41, 95% CI, 0.97-4.97) in men. In female patients, however, there was no higher risk of noncutaneous malignancies.

CONCLUSIONS

This study did not show a higher risk of prostate cancer, gastrointestinal cancer, leukemia, endometrial cancer, or cancer of the nerve and neuroendocrine systems in melanoma patients. No female patients incurred a higher risk of noncutaneous cancers. The increased risk of non-Hodgkin's lymphoma and renal cell carcinoma in men might be attributed to a mutual carcinogenic exposure, an aberration of cell-mediated immunity, a shared genetic susceptibility, increased medical surveillance among cancer patients, a post-therapy effect after cancer management, or factors not as yet clear. Close monitoring of melanoma patients for signs of second malignancy is warranted.

Gamma-delta T-cells in patients with squamous cell carcinoma of the head and neck

In our attempt to characterize a general immune-suppression found in patients with squamous cell carcinoma of the head and neck (SCCHN) we now focused on a subset of CD3 lymphocytes described as gamma/delta-T-cells, a cell type with potential relevance in non-MHC restricted anti-tumor immune responses. Peripheral blood of 33 SCCHN patients and 33 age-matched controls (CON) was evaluated for the frequency of gamma/delta-T-cells among CD3+ T-cells and their onset of apoptosis (Annexin V binding) by multicolor flow cytometry. Results were correlated with clinical parameters. Patients with SCCHN had a significantly higher proportion of gamma/delta-T-cells compared to healthy controls (4.4+/-0.4% for SCCHN vs. 3.0+/-0.3% for CON, p=0.01). However, this increase was not paralleled with a difference in the onset of apoptosis if compared to CON. There was also no correlation between the proportion of gamma/delta-T-cells and tumor stage. However, a significantly higher proportion of gamma/delta-T-cells was found in patients with recurrent or metachronous second primary SCCHN (6.0+/-1.0%) if compared to the other SCCHN (3.8+/-0.4%, p=0.02). In a follow up 3-6 months post-treatment patients showed a decrease of gamma/delta-T-cells among CD3+cells (2.7+/-0.4%, n=4) if they were operated only and an increase if primary radio-chemotherapy (6.7+/-1.7%, n=8) or a combination of operation plus radio-chemotherapy (6.8+/-2.3%, n=3) was applied. Furthermore, patients receiving palliative treatment including radio-chemotherapy had highest values of gamma/delta-T-cells (9.1+/-2.7%, n=4) overall implicating that the treatment modality significantly influences the proportion of gamma/delta-T-cells. Since patients with SCCHN, particularly those with recurrent or second primary disease after treatment, had a higher proportion of gamma/delta-T-cells without signs of a reduced onset of apoptosis this could be due to an increased de novo generation. The current study implies that increased frequencies of gamma/delta-T-cells in patients with SCCHN may not only be the result of tumor-host interactions but the consequence of applied treatment modalities.

Peripheral gammadelta T-lymphocytes as an innovative tool in immunotherapy for metastatic renal cell carcinoma

Renal cell carcinoma represents 3% of solid malignancies in adults and nephrectomy remains the main treatment. Failure of conventional approaches for patients presenting with advanced disease has prompted the exploration of new strategies. This review describes the potential use of peripheral gammadelta (Vgamma9Vdelta2) T-cells in metastatic renal cell carcinoma. This peripheral lymphocyte population from the innate immune system has demonstrated an in vitro antitumor cytotoxicity against primary or established renal cell lines. Moreover, these Vgamma9Vdelta2 lymphocytes undergo a rapid and extensive expansion in vitro as well as in vivo upon stimulation with a synthetic potent agonist, the bromohydrin pyrophosphate molecule. Preclinical results obtained on specific in vitro amplification of Vgamma9Vdelta2 T-cells by bromohydrin pyrophosphate in renal cell carcinoma patients are presented in this review, while Phase I clinical trials are currently running. As there is growing evidence for the low efficiency of monotherapy in cancer patients, innovative approaches combining immunomodulatory gammadelta agonists with classic chemotherapies or administration of antiangiogenic agents are discussed.

In vivo immunomanipulation of V gamma 9V delta 2 T cells with a synthetic phosphoantigen in a preclinical nonhuman primate model

Vgamma9Vdelta2(+) cells represent the major population of gammadelta T cells in primate blood and react in an MHC-unrestricted fashion to a set of low m.w. nonpeptide phosphoantigens. Two types of structurally related agonists have been discovered so far: the natural phosphoantigens (hydroxydimethyl allyl-pyrophosphate or isopentenyl-pyrophosphate (IPP)) acting directly on Vgamma9Vdelta2(+) TCR and aminobisphosphonates, which block the mevalonate pathway in target cells, leading to accumulation of natural phosphoantigens that in turn activate Vgamma9Vdelta2(+) cells. We demonstrate in the cynomolgus monkey that Vgamma9Vdelta2 can be manipulated in vivo with bromohydrin pyrophosphate (BrHPP)/Phosphostim, a potent synthetic agonist for which the mechanism of action is similar to natural phosphoantigens. Although of very short half-life, injection of BrHPP leads to strong activation of Vgamma9Vdelta2, inducing production of a high level of Th1 cytokines. Combination of BrHPP with low-dose rhIL-2 induces specific amplification of effector-memory peripheral Vgamma9Vdelta2 in blood in a dose-dependant manner. This transient response returns to baseline within 10-15 days. Successive infusions of BrHPP and rhIL-2 induce less vigorous expansions, suggesting a progressive exhaustion of the response. As no toxicity is detected with or without IL-2, this scheme represents a promising immunotherapeutic strategy for induction of systemic Th1 cytokines and massive expansion of gammadelta T cell subset with antitumor and anti-infectious properties.

Specific inhibitory action of anisodamine against a staphylococcal superantigenic toxin, toxic shock syndrome toxin 1 (TSST-1), leading to down-regulation of cytokine production and blocking of TSST-1 toxicity in mice

Toxic shock syndrome toxin 1 (TSST-1), produced by Staphylococcus aureus (including methicillin-resistant S. aureus), is a superantigenic toxin responsible for toxic shock syndrome as well as neonatal TSS-like exanthematous disease. TSST-1 exhibits its deleterious effects by leading to the abnormal proliferation of, e.g., Vbeta2+ T cells and overproduction of proinflammatory cytokines. In the present study we examined the inhibitory effect of a Chinese herbal extract, anisodamine, on TSST-1 using human peripheral blood mononuclear cells (PBMCs). Anisodamine inhibited the production of proinflammatory cytokines better than interleukin-10 (an anti-inflammatory cytokine). The inhibitory effect of anisodamine was greater than that of any tropane alkaloid examined. Anisodamine acted directly on both monocytes and T cells in human PBMCs, and the effect was confirmed at the transcriptional level. Inhibition of NF-kappaB activation was also demonstrated. In contrast, no significant inhibition of Vbeta2+ T-cell proliferation was observed. In mice injected with TSST-1, anisodamine treatment significantly decreased serum proinflammatory cytokine levels and prevented TSST-1-induced death. These results suggest that anisodamine specifically acts against the production of cytokines (inflammatory cytokines in particular) and not against Vbeta2+ T-cell proliferation and that anisodamine may have a beneficial effect on TSST-1-associated disease.

The Vgamma2/Vdelta2 T-cell repertoire in Macaca fascicularis: functional responses to phosphoantigen stimulation by the Vgamma2/Jgamma1.2 subset

Circulating Vgamma2/Vdelta2 T cells in human and non-human primates respond to small molecular weight non-peptidic phosphoantigens in a major histocompatibility complex (MHC)-unrestricted manner. These responses are encoded by the Vgamma2/Jgamma1.2 chain of the T-cell receptor and are positively selected during early development to create a biased repertoire in adults. We characterized the Vgamma2 chain in cynomolgus macaques (Macaca fascicularis) to develop a non-human primate model for studying the effects of infection and therapy on the circulating Vgamma2/Vdelta2 T-cell subset. The cynomolgus macaque Vgamma2 chain was highly homologous to the Vgamma2 chain from human beings and rhesus macaques (Macaca mulatta), though we noted conserved substitutions in critical residues within the CDR3 for both macaque species. Despite these substitutions, Vgamma2/Vdelta2+ T cells from cynomolgus monkeys exhibited polyclonal responses to two different phosphoantigens. Proliferative responses were observed with both isopentenylpyrophosphate and alendronate, but stronger interferon-gamma secretory responses were observed with isopentenylpyrophosphate. In vitro stimulation and expansion led to selective outgrowth of the Vgamma2/Jgamma1.2 subset, with a marked shift in the Vgamma2 spectratype. As a result of the less biased starting repertoire for Vgamma2, the cynomolgus macaque constitutes a sensitive model for examining the effects of in vitro or in vivo treatments on the Vgamma2/Vdelta2 T-cell population. Our studies establish the value of cynomolgus macaques as a model for Vgamma2/Vdelta2 T-cell responses to non-peptidic antigens, and further evidence the remarkable evolutionary conservation of this unusual, phosphoantigen-responsive T-cell subset that is found only in primate species.

Cytotoxic effects of gammadelta T cells expanded ex vivo by a third generation bisphosphonate for cancer immunotherapy

Nitrogen containing-bisphosphonates (N-BPs), widely used to treat bone diseases, have direct antitumor effects via the inactivation of Ras proteins. In addition to the direct antitumor activities, N-BPs expand gammadeltaT cells, which exhibit major histocompatibility complex-unrestricted lytic activity. BPs accumulate intermediate metabolites which may be tumor antigens in target cells. The purpose of our study was to clarify the cytotoxicity of gammadelta T cells expanded ex vivo by the most potent N-BP, zoledronate (ZOL). Especially, we focused on the importance of pretreatment against target cells also with ZOL; 1 microM ZOL plus IL-2 increased the absolute number of gammadeltaT cells 298-768 fold for 14 days incubation. The small cell lung cancer and fibrosarcoma cell lines pretreated with 5 microM ZOL showed a marked increase in sensitivity to lysis by gammadeltaT cells. While, untreated cell lines were much less sensitive to lysis by gdT cells. Video microscopy clearly demonstrated that gammadeltaT cells killed target cells pre-treated with ZOL within 3 hr. Pretreatment with 80 microg/kg ZOL also significantly enhanced the antitumor activity of gammadeltaT cells in mice xenografted with SBC-5 cells. These findings show that ZOL significantly stimulated the proliferation of gammadeltaT cells and that gammadeltaT cells required pre-treatment with ZOL for cytotoxic activity against target cells.

Phosphostim-activated gamma delta T cells kill autologous metastatic renal cell carcinoma

Metastatic renal cell carcinoma, inherently resistant to conventional treatments, is considered immunogenic. Indeed, partial responses are obtained after treatment with cytokines such as IL-2 or IFN-alpha, suggesting that the immune system may control the tumor growth. In this study, we have investigated the ability of the main subset of peripheral gammadelta lymphocytes, the Vgamma9Vdelta2-TCR T lymphocytes, to induce an effective cytotoxic response against autologous primary renal cell carcinoma lines. These gammadelta T cells were expanded ex vivo using a Vgamma9Vdelta2 agonist, a synthetic phosphoantigen called Phosphostim. From 11 of 15 patients, the peripheral Vgamma9Vdelta2 T cells were amplified in vitro by stimulating PBMCs with IL-2 and Phosphostim molecule. These expanded Vgamma9Vdelta2 T cells express activation markers and exhibit an effector/memory phenotype. They display a selective lytic potential toward autologous primary renal tumor cells and not against renal NC. The lytic activity involves the perforin-granzyme pathway and is mainly TCR and NKG2D receptor dependent. Furthermore, an increased expression of MHC class I-related molecule A or B proteins, known ligands of NKG2D, are detected on primary renal tumor cells. Interestingly, from 2 of the 11 positive cultures in response to Phosphostim, expanded-Vgamma9Vdelta2 T cells present an expression of killer cell Ig-like receptors, suggesting their prior recruitment in vivo. Unexpectedly, on serial frozen sections from three tumors, we observe a gammadelta lymphocyte infiltrate that was mainly composed of Vgamma9Vdelta2 T cells. These results outline that Vgamma9Vdelta2-TCR effectors may represent a promising approach for the treatment of metastatic renal cell carcinoma.

Characterization of tumor reactivity of human V gamma 9V delta 2 gamma delta T cells in vitro and in SCID mice in vivo

Human Vgamma9Vdelta2 gammadelta T cells are selectively activated by bacterial phosphoantigens and aminobisphosphonates and exert potent cytotoxicity toward various tumor cells. In this study we have characterized the cytotoxic reactivity of gammadelta T cell lines established from healthy donors by stimulation with aminobisphosphonate alendronate toward melanoma MeWo and pancreatic adenocarcinomas Colo357 and PancTu1 lines in vitro and in vivo upon adoptive transfer into SCID mice. Lysis of all tumor cells was enhanced when gammadelta effector cells were preactivated with phosphoantigens. Recognition of MeWo was TCR dependent, as shown by anti-TCR Ab blockade, whereas only the phosphoantigen-mediated increased, but not the basal, lysis of Colo357 and PancTu1 was inhibited by anti-TCR Ab. Furthermore, lysis of Colo357, but not that of MeWo or PancTu1, was completely inhibited by the pan-caspase inhibitor zVAD, indicating different recognition and effector mechanisms involved in the gammadelta T cell/tumor cell interactions. Upon transfer into SCID mice, alendronate-activated gammadelta T cells given together with IL-2 and alendronate significantly prolonged the survival of SCID mice inoculated with human tumor cells. The best results were thus obtained when gammadelta T cells were repetitively given five times over a period of 30 days. With this protocol, human gammadelta T cells prolonged the mean survival of mice inoculated with MeWo melanoma from 28.5 to 87.3 days (p < 0.0001) and in the case of PancTu1 adenocarcinoma from 23.0 to 48.4 days (p < 0.0001). We conclude that an effective gammadelta T cell-based immunotherapy might require activation of endogenous gammadelta T cells with aminobisphosphonate (or phosphoantigen) and IL-2, followed by adoptive transfer of in vitro expanded gammadelta T cells.

Potential of human gammadelta T lymphocytes for immunotherapy of cancer

T lymphocytes are classified into 2 subsets based on their T-cell receptor (TCR) expression. The vast majority of T cells expresses an alphabeta TCR heterodimer. These alphabeta T cells recognize antigenic peptides presented by MHC class I (for CD8(+) T cells) or MHC class II molecules (for CD4(+) T cells). Concepts of cancer immunotherapy are mostly concerned with activation of these MHC-restricted alphabeta T cells. Until recently, a numerically small subset of T cells, which expresses an alternative TCR composed of a CD3-associated gammadelta heterodimer, has received far less attention as a potential agent in cancer therapy. These gammadelta T cells share with alphabeta T cells certain effector functions such as cytokine production and potent cytotoxic activity but recognize different sets of antigens, usually in a non-MHC-restricted fashion. Different subsets of human gammadelta T cells recognize stress-inducible MHC class I-related molecules frequently expressed on epithelial tumor cells or phosphorylated metabolites which can be generated by tumor cells. In line with this, many tumor cells are highly susceptible to gammadelta T-cell mediated lysis. In our article, we summarize the available evidence for a contribution of human gammadelta T cells in tumor defense and discuss potential strategies for the immunotherapy of tumors based on the endogenous activation and/or adoptive transfer of tumor-reactive gammadelta T lymphocytes.

CD3 bright lymphocyte population reveal ?? T cells

BACKGROUND

In routine CD3/CD4/CD8 T-cell analysis, a CD3 bright population of lymphocytes is frequently observed. The aim of the present study was to identify the immunological significance of such CD3 bright lymphocytes.

METHODS

We analyzed samples from 31 healthy adult volunteers, 78 human immunodeficiency virus (HIV)-positive, and 78 renal transplanted patients.

RESULTS

A clearly distinct CD3 bright (frequently CD4-/CD8-) T-cell fraction was observed in 84% of donors and was directly correlated with the fraction of gammadelta T cells (r2 = 0.64). CD3 overexpression on gammadelta T cells was confirmed by a combination of monoclonal antibody staining (CD3-ECD, gammadeltaTCR-FITC, and alphabetaTCR-PE-Cy5) or immunomagnetic purification of gammadelta T cells (i.e., MdFI 20 vs 8.86). The gammadelta T cells expressed CD8 polypeptide chains (alpha and beta) in all possible combinations. The largest proportion, surprisingly, were cells expressing CD8betabeta homodimers (43.8 +/- 16.5%). CD8alphaalpha homodimers were expressed on 14.2% (+/- 12.3) of total gammadelta T cells, whereas CD8alphabeta heterodimers were expressed on 12.2% (+/- 7.5). We also observed a bimodal distribution of the intensity of CD3 fluorescence of gammadelta T cells in immunocompromised patients with a threshold at 105 cell/microl. CD3 bright gammadelta T cells were more frequently observed in HIV patients (29%) compared with renal transplant patients (11%) and healthy donors (3%; chi2 test: P = 0.0007).

CONCLUSIONS

The simple observation of a CD3 bright T-cell subset on CD3/CD4/CD8 routine analysis suggests a high gammadelta T-cell fraction and, in our opinion, should be followed by a complementary analysis to determine precisely the number of gammadelta T cells and to identify their CD8alpha/beta phenotype. When CD3 bright T cells/microl were more than 40%, high gammadelta T cells were detected in more than 87% of cases, with a specificity of 76%. Occasionally, the CD3 bright subset appeared to be strongly homogeneous, suggesting an oligoclonal proliferation that could possibly reveal a chronic localized stimulation or an early lymphoproliferative disorder. Because the gammadelta T cells have interesting immunological peculiarities, the clinical significance of their quantitative abnormality should be clarified in diseases such as HIV, organ transplantation, autoimmunity and lymphoma.

Immune system alterations in lung cancer patients

The immune system plays an important role in the defense against neoplastic disease and immune responses show temporal changes related to circadian variations of antibodies, total lymphocytes in the peripheral blood and cell mediated immune responses. In this study we evaluate. lymphocyte subpopulations and interleukin-2 (IL-2) serum levels in peripheral blood samples collected at four-hour intervals for 24-hours starting at 06.00 h from ten healthy subjects aged 65-79 years (mean age +/- s.e. 67.28 +/- 3.11) and from ten subjects suffering from untreated non small cell lung cancer aged 65-78 years (mean age +/- s.e. 68.57 +/- 1.81). Areas under the curve, mean diurnal levels (mean of 06.00-10.00-14.00 h) and mean nocturnal levels (mean of 18.00-22.00-02.00 h) were calculated, and the presence of circadian rhythmicity was evaluate. When we compared AUC values there was a decrease in CD8bright (T suppressor subset) and an increase in CD16 (natural killer cells) and of IL-2 serum levels in cancer patients. When we compared mean diurnal levels, CD8 (T suppressor/cytotoxic subset) and CD8bright levels were lower, and CD16 levels were higher in cancer patients. When we compared mean nocturnal levels, CD16 and CD25 (T and B activated lymphocytes with expression of the a chain of IL-2 receptor) levels were higher, while CD8, CD8bright, CD20 (total B-cells), TcRd1 (epitope of the constant domain of d chain of T-cell receptor 1) and dTcS1 (epitope of the variable domain of d chain of T-cell receptor1) levels were lower in cancer patients. A clear circadian rhythm was validated for the time-qualified changes in CD4, CD20, HLA-DR with acrophase at night, and CD8, CD8 bright, CD8 dim, CD16, TcRd1 and dTcS1 with acrophase in the morning in the control group. A clear circadian rhythm was validated for the time-qualified changes in CD4 with acrophase at night, in the group of cancer patients. Results obtained in our study show that lung cancer is associated with anomalies of proportion and circadian variations of lymphocyte subsets that must be considered when adoptive immunotherapy has to be planned.

Immune inhibitory effects of renal cell carcinoma extract on lectin and alloantigen-induced peripheral blood and tumor infiltrating lymphocyte blastogenesis

The presence of tumor infiltrating lymphocytes (TIL) has been attributed to the host cell mediated immune response against the evolving malignancy. However, due to specific evasive and escape mechanisms, the immune competent cells are rendered ineffective. One such mechanism may be the production of immune suppressor substance(s), inhibiting lymphocyte proliferation, and subsequently, their transformation into effector cells. To evaluate a possible impact of RCC extract on lectin and alloantigen-induced proliferation of TIL and peripheral blood lymphocytes (PBL) from renal cell carcinoma (RCC) patients and from healthy control human subjects. Tumor extract and TIL were derived from 13 patients with RCC undergoing radical nephrectomy. Tumor infiltrating lymphocytes and PBL from these patients were activated with Concanavalin A (Con-A), Phytohemoglutinine (PHA) or Pokeweed (PW) and the rate of blastogenesis was measured by (3)H Thymidine incorporation. The same procedure was used in assay with PBL from control healthy blood donors. There was a significant reduction (88.6%) in the proliferative response to ConA of TIL compared to PBL from the same patients (P = 0.007). A similar decrease was seen following stimulation by PHA (85.8%, P = 0.01) and PW mitogen (78.5%, P = 0.001). A 79.5% decrease in response level of TIL to alloantigens compared to PBL from RCC patients (P = 0.021), was observed. Lectin induced proliferative response of RCC patients was significantly lower in the presence of RCC extract (82.9%) compared to normal kidney extract (P = 0.008). Alloantigenic stimulation of healthy individual PBL was also decreased significantly in the presence of RCC extract (92.9%, P = 0.0001) compared to normal kidney extract. Similarly, lectin induced stimulation of healthy control PBL in the presence of RCC extract was significantly lower (83.2%, P = 0.003). Our data suggest that RCC extract contains an immune suppressive substance(s), capable of inhibiting lymphocyte proliferative response of tumor infiltrating lymphocytes as well as of PBL from patients and healthy individuals alike. This may be one of the mechanisms by which the tumor evades the transformation of lymphocytes into effector killer cells, and thus affects the biological inter-relationship between tumor and host. Identification of this substance and its gene may provide an effective anti-tumoral treatment modality.

Synaptic transfer by human gamma delta T cells stimulated with soluble or cellular antigens

B, alpha beta T, and NK lymphocytes establish immunological synapses (IS) with their targets to enable recognition. Transfer of target cell-derived Ags together with proximal molecules onto the effector cell appears also to occur through synapses. Little is known about the molecular basis of this transfer, but it is assumed to result from Ag receptor internalization. Because human gamma delta T cells recognize soluble nonpeptidic phosphoantigens as well as tumor cells such as Daudi, it is unknown whether they establish IS with, and extract molecules from, target cells. Using flow cytometry and confocal microscopy, we show in this work that Ag-stimulated human V gamma 9/V delta 2 T cells conjugate to, and perform molecular transfer from, various tumor cell targets. The molecular transfer appears to be linked to IS establishment, evolves in a dose-dependent manner in the presence of either soluble or cellular Ag, and requires gamma delta TCR ligation, Src family kinase signaling, and participation of the actin cytoskeleton. Although CD45 exclusion characterized the IS performed by gamma delta T cells, no obvious capping of the gamma delta TCR was detected. The synaptic transfer mediated by gamma delta T cells involved target molecules unrelated to the cognate Ag and occurred independently of MHC class I expression by target cells. From these observations, we conclude that despite the particular features of gamma delta T cell activation, both synapse formation and molecular transfer of determinants belonging to target cell characterize gamma delta T cell recognition of Ags.

Targeting of tumor cells for human gammadelta T cells by nonpeptide antigens

Human Vgamma2/Vdelta2(+) gammadelta T cells respond to low molecular-mass nonpeptide Ags in a gammadelta TCR-dependent manner. Although requirements of Ag presentation have remained controversial, we have indicated that specific responses of the primary gammadelta T cells to pamidronate were dependent on monocytic adherent cells for Ag presentation. Here, we show that human tumor cells can efficiently present aminobisphosphonate and pyrophosphomonoester compounds to gammadelta T cells, inducing specific proliferation and IFN-gamma production. gammadelta TCR dependency of the response to Ag-pulsed tumor cells was confirmed by using a Jurkat line transfected with a Vgamma2/Vdelta2 gammadelta TCR. Furthermore, gammadelta T cells exhibited markedly enhanced cytotoxicity against the Ag-pulsed tumor cells as compared with untreated tumor cells. Survey of a number of human tumor cell lines of different origins revealed that the majority of them became susceptible for gammadelta T cell-mediated cytotoxicity following the Ag pulsing except for breast cancer lines so far examined, while normal PHA blast cells remained resistant. The results not only imply a unique mode of nonpeptide Ag recognition by human gammadelta T cells but also may provide a novel strategic clue for immunotherapy of human malignancy.