Poly I:C stimulation up-regulates IFN-γ production in human NK cells. Highly purified polyclonal NK cells (A) and the NK92 cell line (B) were left untreated (NT), or stimulated with poly I:C (100 μg/mL) or different doses of IL-2 (A, left) or IL-12 (A, right, and B), in the presence or absence of poly I:C for 24 hours. IFN-γ production was measured in cell culture supernatants. Data presented are representative of 1 out of 3 independent experiments.