EXPRESSION IN CYTOTOXIC T-LYMPHOCYTES OF A SINGLE-CHAIN ANTICARCINOEMBRYONIC ANTIGEN-ANTIBODY - REDIRECTED FAS LIGAND-MEDIATED LYSIS OF COLON-CARCINOMA

In the MD45 mouse cytotoxic T lymphocyte (CTL) hybridoma cell line, we have expressed a chimeric receptor, consisting of the single-chain va riable domains (scFv) of anti-carcinoma embryonic antigen (CEA) mAb li nked to Fc gamma receptor (Fc gamma R) chain via a CD8 hinge. Transfec ted MD45 subclones lysed CEA-positive human colon carcinoma cell lines in an antigen-specific and Fast-dependent manner. The degree of lysis correlated with the level of chimeric receptor expressed on transduce d MD45 subclones. The requirement for an intact Y(65)TGL motif in the signaling gamma chain suggested that interaction of the chimeric recep tor with target cell CEA induced the cytotoxicity of MD45-scFv subclon es. However, MD45 expressing a Y65F mutant chimera still displayed min or levels of lysis following PMA stimulation, suggesting that PMA coul d bypass gamma chain induction of functional Fast. Pretreatment of Pas -resistant CEA-positive colon carcinoma target cells with IFN-gamma in creased their sensitivity of MD45-scFv subclones and Fast-mediated lys is. This study has demonstrated the successful activation of Fast func tion via a chimeric receptor introduced into lymphocytes and the susce ptibility of human colon carcinoma to combined cytokine and CTL treatm ent.