IL‐17 enhances the susceptibility of U‐2 OS osteosarcoma cells to NK cell lysis

SUMMARY We investigated the effect of the proinflammatory cytokine interleukin 17 (IL‐17) on the lysis of osteosarcoma cells by human NK cells. NK cells and U‐2 OS, MG‐63, HOS osteosarcoma cell lines express the IL‐17 receptor, the highest amount being found on U‐2 OS. Pre‐incubation of NK cells with IL‐17 did not affect the cytotoxicity against osteosarcomas, that was increased when U‐2 OS were pre‐incubated with IL‐17. In IL‐17 treated U‐2 OS osteosarcoma cells FACS analysis demonstrated an increased expression of fibronectin among the panel of adhesion molecules assayed, and the treatment with anti‐fibronectin antibodies decreased the NK cytotoxicity. The comparison between interferon gamma (IFN‐γ) treated and IFN‐γ/IL‐17‐treated U‐2 OS showed a decreased susceptibility to NK lysis associated with a reduced expression of CD49f on U‐2 OS treated with IFN‐γ/IL‐17. IL‐17 appears to be a modulator of NK adhesion molecules on U‐2 OS cells but antagonizes with IFN‐γ on NK lysis.