Redirected perforin-dependent lysis of colon carcinoma by ex vivo genetically engineered CTL

The redirection of autologous lymphocytes to predefined tumor target Ags has considerable potential for the immunotherapeutic treatment of cancer; however, robust experimental systems for comparing various approaches have not been developed. Herein, we have generated a single chain variable domain anti-carcinoembryonic Ag (CEA) Fcε receptor I γ-chain fusion (scFv anti- CEA) receptor and demonstrated high-level expression of this chimeric receptor in naive mouse T lymphocytes by retroviral gene transduction. These gene-modified CTL were able to lyse CEA⁺ targets and secrete high levels of IFN-γ following Ag stimulation. Depletion studies demonstrated that specific tumor cell cytotoxicity was mediated by gene-modified CD8⁺ T cells. Importantly, in increasingly stringent tests of efficacy in vive, transduced CTL were sequentially shown to reject CEA⁺ colon carcinoma cells in a Winn assay and then reject established s.c. colon carcinoma in scid or syngeneic mice. Furthermore, using gene-targeted and scFv anti-CEA receptor-transduced donor CTL, perforin and IFN-γ were demonstrated to be absolutely critical for the eradication of colon carcinoma in mice. In summary, we have developed a highly efficient gene transfer system for evaluating chimeric receptor expression in cytotoxic lymphocytes. This series of experiments has revealed the utility of scFv anti-CEA chimeras in providing mouse T cells the capacity to reject colon carcinoma in an Ag- and perforin-specific manner.