Histocompatibility Leukocyte Antigen‐A2402‐restricted Cytotoxic T Lymphocytes Recognizing Adenocarcinoma in Tumor‐infiltrating Lymphocytes of Patients with Colon Cancer

To cast light on T cell‐mediated specific immunity at the tumor site of colon cancer, we investigated whether interleukin‐2 (IL‐2)‐activated tumor‐infiltrating lymphocytes (TIL) from colon cancer show histocompatibility leukocyte antigen (HLA)‐class I‐restricted cytotoxicity against adenocarcinoma. IL 2‐activated TIL from all four HLA‐A24 patients examined lysed HLA‐A2402+ adenocarcinomas, but not HLA‐A2402 tumors. Those of two of the four cases also lysed HLA‐A2402+ squamous cell carcinomas. CD8+ cytotoxic T lymphocyte (CTL) clones recognizing HLA‐A2402+ adenocarcinomas were established from one CTL line. This CTL line produced IFN‐γ upon recognition of an HLA‐A2402‐ adenocarcinoma transfected with HLA‐A2402 cDNA. These results suggest the presence of HLA‐A2402‐restricted CTL recognizing adenocarcinoma at the tumor site of colon cancer. Furthermore, HLA‐A31‐restricted CTL activity was found in IL‐2‐activated TIL from one of two HLA‐A31+ patients, suggesting the existence of HLA‐class I‐restricted CTL involving an allele other than A24