Figure 6.  Activation of cytolytic activity in NK cells also requires high concentrations of IL2 and IL15.
Triplicate cultures containing 0.5 million spleen cells were incubated with various doses of
human IL2 or mouse IL15 for 3 days, then harvested and tested at various dilutions in a 4hr
Cr-release assay against YAC targets.  E:T ratios are based on the starting nos. of cells.
Conclusions
1.  200pM IL2 and IL15 induced little or no cytolytic activity.
2.  Maximal induction of cytolytic activity required at least 20nM IL2 or IL15.
3.  Activation of cytolytic activity in NK cells therefore requires similar high doses of IL2 and IL15
to those required to promote growth.