Alteration of the immunological synapse in lung cancer: a microenvironmental approach

This study was designed to investigate the immunological properties of stroma reaction T cells and tumoral cells by comparison with non-tumoral lung tissue and local lymph nodes in order to explore interactions between tumour cells and the immune system. Immunodetection of major histocompatibility complex (MHC) molecules, CD3/T cell receptor (TCR) complex and T cell subsets markers was carried out in situ on frozen sections, and the semi-quantitative expression of CD3, CD4 and CD8 was examined in flow cytometry on lymphocytes of nodal, tumoral and healthy lung tissue from 62 patients with non-small cell lung cancer. This study showed alterations on lymphocytes and tumour cells in lung cancer, consistent with an impairment of T cell activation. CD3, TCR alpha beta and accessory molecules expression is down-modulated on peri- or intra-tumoral lymphocytes. MHC class I and class II molecules are down-modulated significantly on tumour cells. Other differences were noted, such as the reversed CD4/CD8 ratio of tumour infiltrating cells, compared to healthy lung tissues, consistent with the development of cytotoxic anti-tumoral responses. This study reports on the presence of a strong in vivo immunomodulating effect of tumour cells in human non-small cell lung cancer, likely to impair proper formation of the immunological synapse.