Oligoclonal T lymphocytes infiltrating human lung cancer tissues

To clarify the nature of tumor-infiltrating lymphocytes (TILs), we investigated the possible clonality of the T cells in TILs freshly isolated from human primary lung cancer tissues by assessing the rearrangement pattern of the T-cell receptor (TCR) gene beta locus using Southern blotting. First, in phenotypic analysis, TILs represented different populations among corresponding peripheral blood lymphocytes (PBLs) with an increased proportion of CD20+ (B) cells as well as a decreased proportion of CD16+ (natural killer) cells, and a variable CD4/CD8 ratio. Considering the central role of T cells in immune responses, we analyzed TCR beta gene rearrangement patterns in TILs and corresponding PBLs from 12 patients. In 10 of the 12 cases, TILs showed one or more TCR gene rearrangement bands with a predominance of the C beta 2 gene, in which 2 types of common rearranged band were observed among the cases with different clinical profiles in terms of histological types and disease stage, with bands at about 9.5 kb in 7 and at 11.5 kb in 8 patients. On the other hand, predominant rearranged bands were hardly detected in corresponding PBLs except in 2 cases. From these results, we conclude that TILs in lung cancer tissues frequently contain oligoclonal T-cell populations, which were probably sensitized by relatively common antigens at the tumor sites.