ROLE OF TNFα/TNF-R1-SIGNALING PATHWAY IN CYTOTOXIC ACTIVITY OF DENDRITIC CELLS AGAINST GLIOBLASTOMA CELL LINES

Dendritic cells (DCs) of patients with high-grade brain glioma exhibit impaired expression of membrane TNFα associated with low DC cytotoxicity against TNF-R1-expressing tumor cell line HEp-2. To assess the significance of these findings, we investigated a role of TNFα/TNF-R1-signaling pathway in DC cytotoxic activity against allogenic and autologous cell lines obtained from high-grade glioma tissues. DCs were generated by culturing of plastic-adherent peripheral blood mononuclear cells in presence of GM-CSF and IFNα for 4 d followed by LPS addition for 24 h (IFN-DCs). The tumor cell lines were obtained from tissues of 11 patients with glioblastoma multiforme. According our findings glioblastoma cells were sensitive to lysis mediated by donor IFN-DCs. The level of DC cytotoxic effect against cell lines obtained from different glioma patient tissues varied from 20 to 72.2%. DC lysis of 8 out of 11 glioblastoma cell lines exceeded 40%. Glioblastoma cell lines expressed both TNF-R1 and TNF-R2 receptors, but mostly – TNF-R1. However, rTNFα did not show cytotoxic activity towards glioblastoma cell lines. Blocking of TNFα/TNF-R1-signaling pathway by treating of donor IFN-DCs with soluble rhTNFR1 receptor led to partial decrease of DC cytotoxic activity against 5 out of 6 tested glioblastoma cell lines by 11-40% (median of suppression 24%). Glioblastoma patient IFN-DCs which were characterized by an impairment of TNFα/TNF-R1-signaling pathway lysed these glioblastoma cell lines, however median of DC cytotoxicity was 30% lower than that of donor values (31.5 vs 45.1%; р = 0.003). Cytotoxic activity of IFN-DCs of the glioblastoma patient against autologous tumor cells resistance to TNFα/TNF-R1-signaling pathway was comparable with level of cytotoxicity of donor IFN-DCs. Thus, glioblastoma cells are sensitive to cytotoxic activity of DCs mediated via TNFα/TNF-R1-signaling pathway, but the defect of this mechanism in IFN-DCs of glioblastoma patients determines significant decrease of DC cytotoxicity towards glioblastoma cells.