KpOmpA and flagellin induce CD69 expression and proliferation of NK cells. Freshly isolated CD56⁺CD3-NK cells were unstimulated or were stimulated with 1 μM KpOmpA, flagellin, or TT in the absence or in the presence of 200 U/mL IL-2 or 1 ng/mL IL-10. CD69 expression (A) and proliferation (B) were determined as described in “Materials and methods.” Results are expressed as mean ± SD (n = 5).