Immunosuppressive effects of soluble factors secreted by head and neck squamous cell carcinoma on dendritic cells and T lymphocytes

Abstract 

Recent observations suggest that the inability of the immune system to mount an effective immune response against head and neck squamous cell carcinoma (HNSCC) could be a result of the immunosuppression mediated through soluble factors that are secreted by tumour cells. Therefore, we investigated the effects of conditioned medium obtained from cultures of HNSCC cell lines (HNSCC-CM) on the function of dendritic cells (DC) and T cell immune response. In our study, we could not observe any inhibitory effect of HNSCC-CM on the maturation and the cytokine secretion pattern of DC. On the contrary, HNSCC-CM from two of three cell lines consistently decreased the quantity of IFN-γ- and IL-4-secreting T cells upon restimulation in vitro. In conclusion, our data suggest that soluble factors secreted by HNSCC cells directly inhibit the function of effector T cells, rather than impeding the process of antigen presentation.

Keywords:  Head and neck squamous cell carcinoma, Soluble factor, Immunosuppression, Dendritic cells, T lymphocytes, Cytokines

Abbreviations:  HNSCC, head and neck squamous cell carcinoma, SCC, squamous cell carcinoma, HNSCC-CM, conditioned medium derived from the cultures of HNSCC cells, MCM, monocytes-conditioned medium, PBMC, peripheral blood mononuclear cells, DC, dendritic cells, imDC, immature DC, maDC, mature DC, TGF-β, transforming growth factor-β, IFN-γ, interferon γ, IL, interleukine, Th, helper T lymphocytes, Treg, regulatory T lymphocytes