Gamma-Delta T-Cells in Patients with Ovarian Carcinoma

Abstract

Ovarian cancer is the fifth most common cause of death from all cancers among women in the Western world and the most lethal of all gynecological cancers. The epithelial ovarian carcinomas (EOC) represent approximately 90% of all human ovarian malignant neoplasm. The five-year survival rate for patients with EOC is attributed to late diagnosis and poor response to therapy. T-cells play an important role in tumor immunity of EOC, evidence includes infiltrating CD3+ T-cells in EOC lesions and a specific antigen driven immune response. Human gd TCR + T-cells are a minor subset of T-cells (1-10%) in the peripheral blood. The majority of the T cells in the peripheral blood are aß TCR + T-cells. Like the aß T-cells, gd TCR + T-cells bear a T-cell receptor that functions in antigen recognition. Most importantly most gd TCR+ T cells recognize mainly whole proteins. In contrast, aß TCR+ T cells primarily recognize peptide in association with MHC. Upon specific antigen recognition, these T cells undergo clonal expansion, generating multiple identical T cell clones. Previously in our lab clonal expansion of ab TCR+ T cells was observed in patients with EOC. Also preliminary data indicate that clonal expansion of gd TCR+ T cells in patients with EOC. The hypothesis to be tested in this study is whether clonally expanded gd TCR+ T-cells in patients with EOC, are able to recognize and kill EOC tumor cells. Data from recent studies show that tumor infiltrating gd TCR+ T cells recognize and have antitumor activity towards epithelial derived cancer cells. Following V-specific amplification of the various gd T-cell receptors (TCR) chains we observed the presence of statistically significant populations of oligoclonal g-chain and d-chain TCR+ transcripts in the EOC samples studied. To further characterize the gd TCR+ T-cells in EOC lesions, full-length transcripts of the most clonally expanded Vg(II)9- and Vd2-chain TCR transcripts from EOC tumors were constructed. These, as well as additional, full-length transcripts were transduced into a mutant TCR-negative Jurkat T cell line. The transduced cells were analyzed by flow cytometry (FACS) for expression of gd TCR on the cell surface. gd TCR+ CD3+ transduced T cells were then incubated with the ovarian cancer cell lines, SKOV3, CAOV3 or OV2774. Following co-culture experiments of these cancer cells with gd TCR+ CD3+ transduced T cells we observed killing of the target cell (SKOV3, CAOV3 and OV2774) by various gd TCR + T cell transduced cell lines. This killing was not observed by control T cell lines transduced either with vector only or single chain of TCR. Furthermore, the production of cysteine proteases such as caspase 3/7, procaspase 8 and 9 involved in target cell death were also observed following co-incubation experiments. These data suggest that our gd TCR+ transduced T cells induce SKOV3, CAOV3 and OV2774 cancer cell death measured by cytotoxicity and activation of cell death proteases.