Expansion and immunological study of human tumor infiltrating gamma/delta T lymphocytes in vitro

Targeting solid tumors via T cell receptor complementarity-determining region 3delta in an engineered antibody

Human Vdelta2 gammadelta T lymphocytes killed multiple solid tumors, even displaying comparable therapeutic efficacy with anti-tumor chemical-cis-platinum in an adoptive experiment in both nude and SCID murine model shown in present study. We previously found that T cell receptor (TCR) gammadelta recognize tumors via complementarity-determining region 3 (CDR3), briefly named as CDR3delta. Based on characteristics of specific binding of CDR3delta to tumor targets, we developed a novel tumor-targeting antibody, whose CDR3 in heavy chain is replaced by CDR3delta sequence derived from human ovarian carcinoma (OEC) infiltrating gammadelta T cells (gammadeltaTILs). This CDR3delta-grafted antibody OT3 exhibited specific binding activities to OEC line SKOV3 both in vitro and in vivo, which included specific binding to several tumor cell lines, interacting with heat shock protein (HSP) 60 and triggering ADCC against tumors in vitro, as well as displaying tumor imaging by radioisotope 99mTc-labeled antibody OT3 in vivo. Moreover, immunotoxin OT3-DT, CDR3delta-grafted antibody OT3 chemically conjugated with diphtheria toxin (DT) showed the anti-tumor effect on the growth of several solid tumors including OEC, cervix adenocarcinoma, hepatocellular carcinoma, and rectum adenocarcinoma to various extents in nude mice. Therefore, we have found and confirmed a novel therapeutic strategy for targeting solid tumors, making use of immune recognition characteristics of gammadelta T cells.

Ozone exposure impairs antigen-specific immunity but activates IL-7-induced proliferation of CD4-CD8- thymocytes in BALB/c mice

It is well known that ozone (O3), a potent reactive oxidant and air pollutant, induces respiratory inflammation and hyperresponsiveness upon inhalation. It was previously shown that O3 exposure (0.6 ppm, 10 h/day for 15 days) not only results in local bronchial inflammation, but also affects the nervous system and thymocyte proliferation, and places mice under oxidative stress. In the present study, data showed that O3 exposure could impair both the natural killer (NK) cell activity and the proliferation potential of spleen T cells to a specific antigen stimulus. Immunological function assays indicated that O3 exposure attenuated the proliferation of spleen mononuclear cells induced by concanavalin A and decreased CD4+ and CD28+ lymphocyte subsets. However, supplementation with natural antioxidants protected mice from O3-induced dysfunction of splenocyte proliferation. Meanwhile, O3 exposure resulted in a decline of mitogen-induced IL-2 production in splenocytes. It was also found that O3 exposure dramatically enhanced the proliferation of CD4-CD8- thymocytes stimulated by recombinant mouse interleukin-7 (rmIL-7), which is usually observed during the mammal aging process. Taken together, data conclude that short-term repetitive O3 exposure damages both innate and acquired immunity via altering the lymphocyte subset and cytokine profile, and via impact on thymocyte early development. O3-induced oxidative damage is one of the key factors leading to immune dysfunction in this mouse model.

Gammadelta T cells recognize tumor cells via CDR3delta region

The principles governing gammadelta T cell specificity and diversity remain unclear due to lack of detailed structural analysis. To elucidate key structural basis of the specificity of gammadelta TCR for tumors, we analyzed the binding activities of synthesized TCR Vdelta2 CDR3 peptides derived from tumor infiltrating lymphocyte (TIL) s in ovarian epithelial carcinoma (OEC) via biospecific interaction analysis approach, enzyme immunoassay and immunofluorescence assays. Besides, we used human CDR3delta grafted-Ig to repeat major tests. We found that synthesized OEC-derived CDR3delta peptides could bind specifically to tumor cell lines and tissues. CDR3delta-graft Ig showed a similar binding specificity with CDR3delta peptides, suggesting the determinant role of CDR3delta in antigen binding. Moreover, CDR3delta peptide-mediated binding specificity was blocked by pre-incubation with same peptide, which decreased the cytotoxicity of gammadelta T cells to OEC cells in vitro. Our finding indicates that CDR3delta peptide could mimic antigen-binding specificity of gammadelta TCR. Our strategy provides a novel, simple and convenient approach to investigate the binding activity and function of gammadelta TCR.

Membrane HSP70: the molecule triggering gammadelta T cells in the early stage of tumorigenesis

Many studies support the supposition that HSPs expressed on the cell membrane play an important role in cancer immunity. In the present study, we demonstrated that HSP60 and HSP70 are markedly increased on the cell membrane of human Epstein-Barr virus (EBV) transformed B cells. In order to investigate whether these molecules were involved in the response of human gammasigma T cells to transformed cells, the cytotoxicities of gammasigma T cells to transformed cells with or without an HSP60/70 gene knockdown were evaluated. gammasigma T cells showed marked cytotoxities to transformed cells. Down-regulation of HSP70 expression could inhibit the reactions, whereas down-regulation of HSP60 expression had little such effect. Moreover, HSP72 could significantly induce human gammasigma T cells to proliferate in vitro. Taken together, our data indicated that HSP60 and HSP70 could be valuable biomarkers for the prediction of early stage in tumorigenesis. Additionally, HSP72 might be a potential candidate of the adjuvant for gammasigma T cells in tumor immunotherapy.

Vdelta1 T cell receptor binds specifically to MHC I chain related A: molecular and biochemical evidences

Human MHC class I chain-related A (MICA) is a tumor-associated antigen that can be recognized by Vdelta1 subset of tumor-infiltrating gammadelta T cells. We previously reported that immobilized recombinant MICA protein could induce the proliferation of tumor-infiltrating Vdelta1 gammadelta T cells in vitro. But there has been no direct evidence showing the engagement of gammadelta T cell receptors (TCR) of the induced cells with MICA. In the current investigation, we show that MICA induces specific cytolytic activity of the expanded gammadelta T cells. We expressed the coupled V domains from the MICA-induced T cells as a single polypeptide chain Vdelta Vgamma TCR (gammadelta scTCR). Such scTCR can specifically bind MICA of HeLa cells. Direct interaction of gammadelta scTCRs with in vitro expressed MICA was monitored using an IAsys biosensor. We found that the Vdelta1 scTCR can specifically bind to immobilized MICA molecule and MICA alpha1alpha2 domains are responsible for the binding reaction.

Immobilized MICA could expand human Vdelta1 gammadelta T cells in vitro that displayed major histocompatibility complex class I chain-related A-dependent cytotoxicity to human epithelial carcinomas

Human major histocompatibility complex class I chain-related A (MICA) is a human leucocyte antigen-related polymorphic molecule, which is expressed on many kinds of epithelial tumours and can be recognized by the Vdelta1 subset of gammadelta T cells. In the present study, monoclonal antibodies (MoAbs) were produced in mice immunized with recombinant MICA (rMICA)*008. It was found that MICA was expressed on ovarian and colonic tumour tissues and could be detected by these anti-MICA MoAbs. The immobilized rMICA could induce the proliferation of human ovarian epithelial carcinoma- or colonic carcinoma-derived gammadelta T cells of the Vdelta1 phenotype in vitro. These Vdelta1 T cells displayed a strong, broad-range cytolytic activity towards tumour cell lines positive for MICA. The efficiency of this cytolytic activity depended greatly on the level of MICA expressed on the cell surface and could be inhibited by anti-MICA MoAbs. Therefore, MICA may play an important role in immune responses against epithelial tumours and function as a stimulating factor for the growth of Vdelta1 gammadelta T cells, whereas MICA-reactive Vdelta1 gammadelta T cells might serve as a new candidate for adoptive cellular therapy of tumours.

Clonal diversity of the T-cell population responding to a dominant HLA-A2 epitope of HER-2/neu after active immunization in an ovarian cancer patient

Natural antigen processing and presentation of antigen is thought to be important for the generation of a broad functional repertoire of antigen-specific T cells. In this study, the T-cell repertoire to an immunodominant human leukocyte antigen A2 (HLA-A2) binding peptide epitope of HER-2/neu, p369-377, was examined in a patient following immunization with a peptide-based vaccine consisting of helper peptides encompassing HLA-A2 peptide epitopes. The responding T-cell repertoire generated was both phenotypically and functionally diverse. A total of 21 p369-377 clones were generated from this patient. With the exception of two clones, all clones were CD3(+). Sixteen of the clones were CD8(+)/CD4(-). Five of the clones were CD4(+)/CD8(-), despite being generated with an HLA-A2 binding peptide. Nineteen of 21 of clones expressed the alpha beta-T-cell receptor (TCR). The remaining two clones expressed the gamma delta T-cell response (TCR). Selected alpha beta-TCR clones, both CD8(+) and CD4(+), could lyse HLA-A2 transfected HER2 overexpressing tumor cells and p369-377-loaded B-lymphoblastic cell line. In addition to their lytic capabilities these clones could be induced to produce interferon-gamma (IFN-gamma) specifically in response to p369-377 peptide stimulation. The 2 gamma delta-TCR clones expressed CD8 and lysed HLA-A2(+) HER-2/neu(+) tumor cells, but not HLA-A2(-) HER-2/neu(+) tumor cells. One of gamma delta-TCR clones also released IFN-gamma directly in response to p369-377 stimulation. These results suggest that a tumor antigen TCR, directed against a specific epitope, can be markedly polyclonal at multiple levels including CD4/CD8 and TCR.

Antitumor activity of expanded human tumor-infiltrating gammadelta T lymphocytes

BACKGROUND

The objective of this study was to investigate the antitumor activity of selectively expanded gammadelta T cells in tumor-infiltrating lymphocytes (gammadeltaTILs) or tumor ascites lymphocytes (gammadeltaTALs) from patients with colorectal and ovarian epithelial carcinoma (OEC) in vitro and in vivo.

METHODS

gammadeltaTILs/TALs were expanded by the solid-phase antibody method; their cytolytic and proliferative activities in vitro were detected by the MTT method and 3H-TdR incorporation and their effect in vivo was evaluated by the nude mice model.

RESULTS

Expanded gammadeltaTILs from colorectal tumors demonstrated marked cytotoxicities to allogeneic human colon adenocarcinoma HR8348 and lymphoma Daudi cells, as well as xenogeneic murine thymoma EL-4 cell lines. Cytokines, including IL-2, IL-4, IL-12, IL-15, TNF-alpha and INF-gamma, could promote the cytotoxicities of gammadeltaTILs to tumor cells, whereas IL-10, GM-CSF and TFG-beta had no effect on such killing activities. Rested gammadeltaTILs could proliferate strongly in response to mitomycin C-treated Daudi and EL-4 tumor cells, but not to HR8348 tumor cells, suggesting that the latter might possess only cytotoxicity-related antigen recognized by gammadeltaTILs. Either alphabetaTILs or gammadeltaTILs from patients with OEC displayed cytotoxicities to allogeneic or autologous OEC cell lines at a similar strength in vitro. Transferring gammadeltaTILs into Daudi cell-bearing BALB/c nude mice with an injection of IL-2 was able to maintain a high survival rate of the mice for 30 days, when compared with mice treated with alphabetaTILs or without any treatment (p < 0.05). Without coinjection of IL-2, after 3 months of Daudi tumor inoculation, a high survival rate was observed in gammadeltaTIL-treated mice. Similarly, adoptive gammadeltaTALs from the ascites of patients with OEC transferred into nude mice displayed a stronger antitumor response to OEC SKOV3 cells than alphabetaTALs in vivo. Tumor volumes in gammadeltaTAL-treated mice were smaller than in alphabetaTAL-treated or non-TAL-treated mice within the period from day 23 to day 50 after tumor inoculation (p < 0.05). Fifty days after SKOV3 tumor inoculation, a decreasing trend of carcinogenic rate was observed in gammadeltaTAL-treated nude mice.

CONCLUSION

Taken together, our results suggest that gammadeltaT cells could be a new candidate for adoptive immunotherapy in the future treatment of patients with cancer.