IL-18/IL-15/IL-12 synergy induces elevated and prolonged IFN-γ production by ex vivo expanded NK cells which is not due to enhanced STAT4 activation.

•Expanded NK cells respond to IL18/IL12 with robust IFNγ and TNFα production.•NK cells maintain elevated IFNγ production but not TNFα after removal of IL18/IL12.•IL18/IL12 induces unique IFNγ+ population distinct from unstimulated IFNγ+ NK cells.•IL18/IL12 induction and maintenance of IFNγ is not due to enhanced STAT4 activity.•Elevated and prolonged IFNγ production is mediated by up-regulation of IFNγ mRNA.