T Cell Response to Embryonal Carcinoma F9 Cells: Induction and Characterization of T Cell Receptor αβ(+) Double‐negative Cytotoxic T Lymphocytes

We investigated the mechanism of T cell response to marine embryonal carcinoma F9 cells. Thy‐1(+), CD4(−), CD8(−) (double‐negative) cytotoxic effector cells were induced in spleen cells obtained from immune A.BY mice to F9 cells, and the cytotoxic activity was major histocompatibility complex (MHC)‐unrestricted. Furthermore, CD4(+) T cells were essential for the induction of double‐negative cytotoxic T lymphocytes directed to F9 cells. Most of the double‐negative cytotoxic T lymphocyte lines obtained by long‐term culture of the effector cells had CD3 molecule and T‐cell receptor β chain on their cell surface, and the CDS molecule was found to be involved in target cell recognition. The T cell receptor αβ(+) double‐negative cytotoxic T lymphocyte line (2A5) also lysed various tumor cells in a non‐MHC‐restricted manner, but did not lyse concanavalin A‐stimulated blasts of 129 strain, from which F9 cells had originated. These results indicate that T cell receptor αβ(+) double‐negative cytotoxic T lymphocytes induced by F9 cells recognize a common antigen(s) expressed on F9 cells and other tumor cells but not minor histocompatibility antigens.