Identification of a new endoplasmic reticulum-resident protein recognized by HLA-A24-restricted tumor-infiltrating lymphocytes of lung cancer.

To help clarify the molecular basis of tumor immunology in lung cancer, we have investigated antigens recognized by HLA-A24-restricted CTLs established from T cells infiltrating into lung adenocarcinoma and report a new gene encoding tumor epitopes recognized by the CTLs. This gene was located on chromosome 4q31.22 and encoded an unreported endoplasmic reticulum-resident protein with 412 deduced amino acids. This protein had a molecular mass of 46 kDa and was expressed in the majority of malignant cells and tissues tested, with the exception of T-cell leukemia cells, but was not expressed in a panel of normal cells and tissues, except in those of the testis, placenta, and fetal liver. Two peptides at positions 13-20 and 75-84 were recognized by the CTLs and had an ability to induce HLA-A24-restricted and tumor-specific CTLs in peripheral blood mononuclear cells of lung cancer patients. Thus, these peptides might be appropriate molecules for use in the specific immunotherapy of HLA-A24+ patients with lung and other cancers.