(A) IM-9 target cells treated with JAK inhibitors (JAK inhib.) for 12 hours and subsequently incubated with NK-92 at a 1:1 E/T ratio. NK-92 cells are nearly 100% NKG2A⁺, and the analysis of apoptotic cells was performed on gated target cells (NKG2A negative). Target cells alone incubated with inhibitors (left scatter plots) were analyzed for the level of apoptosis induced by the JAK inhibitors, and these values were subtracted from the level of apoptosis induced by addition of NK-92 cells (right scatter plots). (B) Increased apoptosis induced by NK-92 cells after treatment of target cells with 2 JAK inhibitors. Results are compared with untreated targets incubated with NK-92 cells. Data represent the mean percentages ± SEM obtained in 3 separate experiments. (C) IM-9-JAK1-KO and IM-9-JAK2-KO cells were treated with medium alone or 40 nM JAK inhibitor 1 or 1 μM AG-490 for 12 hours and subsequently incubated with NK-92 effector cells. Induced apoptosis was compared with IM-9 cells expressing a control shRNA (shCTRL-2). Data represent the mean ± SEM of 2 separate experiments. (D) NKL and NK-92 cells were pretreated with different concentrations of JAK inhibitors and tested for their reactivity against IM-9 using Annexin V/7AAD. Data represent the mean percentages of 3 separate experiments ± SEM tested in duplicate. (E) Percent apoptosis induction by purified primary NK cells after IM-9 treatment with different concentrations of 2 JAK inhibitors. *P < 0.01, **P < 0.05 compared with target cells without inhibitor.