IκBα°ϵ° NK cells have a defect in IFN-γ production. (A) Splenic NK cells (10⁴ cells) from Rag° mice or IκBα°ϵ° chimeras were stimulated for 24 hours with the indicated combinations of IL-12 and/or IL-18 and IFN-γ release measured by ELISA. Error bars represent SEM. (B) Splenocytes from WT or IκBα°ϵ° chimeras were stimulated for 7 hours with a combination of IL-12 and IL-18 (for IFN-γ) or with PMA and calcium ionophore (for IL-13, GM-CSF) and were analyzed by intracellular staining. Analysis was performed on electronically gated CD3^-DX5⁺ cells. Percentages of positive cells are shown in each panel. One representative experiment of 3 to 6 is shown.