The aim of the present study was to elucidate the tumor-specific cellular immunological responses occurring in a patient with large cell carcinoma of the lung who had no evidence of recurrence following surgical resections of both a primary lung lesion and a metastatic adrenal lesion. We analyzed an autologous tumor-specific cytotoxic T lymphocytes (CTL clone F2b), which were HLA-A*2402 restricted from regional lymph node lymphocytes. The F2b possessed T cell receptor (TCR) using the Vα5 and Vβ7 gene segment. The existence of precursor CTL (pCTL) against autologous tumor cells (A904L) was analyzed using CTL clone-specific PCR. Lymphocytes with the same TCR as F2b were detected in the primary tumor tissue, regional lymph node and the peripheral blood collected from the patient 3 years after the operation. Using the F2b, we identified a cDNA clone encoding the tumor antigen using cDNA expression cloning method. The gene was found to encode splicing variant of the Tara gene. Finally, we identified the 9-mer Ag peptide, using constructions of mini-genes. The F2b recognized 3 out of 7 HLA-A24 positive allogeneic tumor cell lines and in 1 out of 7 HLA-A24 negative allogeneic tumor cell lines when transfected with HLA-A24. This peptide is therefore considered to be potentially useful for performing specific immunotherapy in a significant proportion of lung cancer patients bearing HLA-A24. © 2006 Wiley-Liss, Inc.