p38 MAPK activity controls poly I:C–triggered up-regulation of cytotoxic activity and CXCL10 production in human NK cells. (A) The NK92 cell line was stimulated with poly I:C (closed symbols) or left untreated (open symbols) in the presence (squares, triangles) or absence (circles) of SB203580 pharmacologic inhibitor for 24 hours; cytotoxic activity was then tested against K562 target in a 4-hour 51Cr release assay. These data are representative of 1 of 2 independent experiments. (B) The NK92 cell line was stimulated with poly I:C in the presence or absence of SB203580. RT-PCR with specific primers for CXCL10 and for β-actin (as control) was then performed on total RNA. These data are representative of 1 out of 4 independent experiments. (C) CXCL10 secretion in culture supernatants of untreated (empty bars) or poly I:C–stimulated highly purified polyclonal NK cells and NK92 cells (solid bars), in either the presence or absence of SB203580, was quantitated by specific ELISA. These data are representative of 1 out of at least 4 independent experiments.
