Comparative T-cell oligoclonality in lung, tumor and lymph nodes in human non-small cell lung cancer

In lung cancer as in other malignancies, tumor formation induces the development of local and systemic antitumoral immune responses. The tumor itself becomes surrounded by a local stroma reaction containing inflammatory cells, a large part of which being tumor infiltrating T-lymphocytes. This study was designed to investigate the potential clonality of these T-cells in non-small cell lung cancer. Two complementary methods where used: exploration of the Vβ TCR repertoire usage in flow cytometry and analysis of the Vγ TCR repertoire in multiplex PCR and gradient gel electrophoresis. These techniques were applied respectively to eluted fresh lymphocytes and extracted DNA from healthy lung tissue, tumor and lymph nodes from 44 patients. There was a good correlation between the two techniques used. An oligoclonal repertoire restriction was noted in most of the cases and in the three types of tissues studied suggesting the presence of tumor-specific clones. Moreover, Vβ14 appeared to be the most frequent specificity used whatever the tissue considered, while Vβ13.1 appeared to be selectively used in the stroma reaction of epidermoid lung carcinomas. A restricted TCRγ band was also present in these tumors, and two more bands of TCRγ where selectively present in adenocarcinomas. The demonstration of both α-β and γ-δ TCR restriction suggests both the recruitment of specific T-cells and their local proliferation within the tumoral tissue. The same feature in healthy lung tissue indicates that it might already be the site of specific anti-tumoral T-cell reactivity. In conclusion, this study reports on the presence of oligoclonal T-cell responses in most cases of non-small cell lung cancer. The comparison of tumor, healthy tissue and lymph nodes showed some degree of patient-dependent similarities suggestive of tumor specificity.