(A) Treatment of mice with B-E29 causes a dose dependent decrease in the effect of hIL-15 on NK1.1+ cells. An irrelevant IgG1 control has no effect on the response to IL-15. (B) Treatment of mice with B-E29 significantly inhibited the effects of hIL-15 and pre-associated hIL-15/IL-15Rα complex. Error bars indicate SEM values. *P < 0.05, **P < 0.01, ***P < 0.001. hIL-15, human interleukin-15; hIL-15/sIL-15Rα, pre-associated complex of human IL-15 and soluble IL-15 receptor α; IL-15, interleukin-15; PBS, phosphate-buffered saline.