Tumour-infiltrating lymphocytes in non-small cell lung cancer are activated T lymphocytes.

This study was carried out in order to investigate the local immune reaction of tumour-infiltrating lymphocytes (TILs) in the primary tumours of non-small cell lung carcinomas. Thirty non-small cell lung cancer (NSCLC) patients were included. The tumour tissue was taken at thoracotomy and monocellular suspension of the tumour was obtained by mechanical disaggregation. Dual-coloured flow cytometric analysis of TILs and their corresponding peripheral blood lymphocytes (PBLs) was performed. Tumour-infiltrating lymphocytes contained significantly higher proportions of CD3(+) T lymphocytes and CD8(+) T lymphocytes than the corresponding PBLs (82.0%+/-13.9% vs 66.3%+/-10.6% for CD3, P<0.001; 39.0%+/-18.4% vs 26.4%+/-5.2% for CD8, P<0.001). Tumour-infiltrating lymphocytes contained significantly higher proportions of activated memory lymphocytes than PBLs did (9.8%+/-8.6% vs 1.3%+/-1.5% for CD25, P<0.001; 40.5%+/-30.2% vs 10.2%+/-14.8% for CD71, P<0.001; 75.5%+/-11.9% vs 28.6%+/-9.8% for HLA-DR, P<0.001). These findings were also found in both CD4(+) TILs and CD8(+) TILs. The TILs of NSCLC contained higher proportions of T lymphocytes and CD8(+) lymphocytes than their corresponding peripheral bloods. The proportions of activated memory lymphocytes were also significantly higher in the TILs, both in CD4(+) TILs and CD8(+) TILs, than the corresponding PBLs.