Natural cytotoxicity in the absence of IκBα°ϵ°. (A) Freshly isolated splenocytes from WT (▴) and IκBα°ϵ° (•) chimeras showed similar lytic activity against Cr⁵¹ -labeled YAC-1 target cells. NK cell-target cell ratios were normalized using flow cytometric analysis. One representative experiment of 2 is shown. (B) Freshly isolated splenocytes from WT (▴) and IκBα°ϵ° (•) chimeras showed similar lytic activity against CHO target cells. (C) WT (black symbols) and IκBα°ϵ° (gray symbols) splenocytes were stimulated for 12 hours with IL-2 alone (circles) or cytokine combination (IL-2+IL-12+IL-18) (triangles) prior to analysis of lytic activity against YAC-1 target cells. Error bars represent SEM.