The inducibility of cytotoxic T lymphocytes (CTL) that react with carcinoembryonic antigen (CEA) was tested in cancer patients with elevated (more than 5 ng/ml) serum CEA levels when antigen presentation was carried out with paraformaldehyde-fixed adhesive peripheral blood mononuclear cells (PBMC) from the patient that had been pre-loaded with CEA652(9), an HLA-A2402-restricted tumor antigenic peptide derived from CEA. By culturing fresh autologous PBMC on the fixed cell layer in medium containing interleukin-1, -2, -4 and -6. three out of eight patients developed CTL. The CTL from two of these patients killed CEA-protein-producing gastric cancer cells carrying HLA-A2402 and the cells from the remaining patient killed CEA-non-producing stomach cancer cells pre-loaded with CEA652(9). The results suggest that a single antigenic peptide on the fixed adhesive cells will allow the ex vivo induction of peptide-reactive CTL that are easier to handle and allow antigen presentation without tedious preculture of the "professional" antigen-presenting dendritic-cells.