(A) TYRO3, AXL, and MERTK expression was determined after primary human NK cells were co-cultured with or without K562 cells at an effector (E)/tumor (T) ratio of 10:1 for 24 h. Representative flow cytometry plots from 4 different donors. Summary data of A are shown in (B). (C) Primary human NK cells were co-cultured with K562 at an E/T ratio of 1:1 for the indicated times, and TYRO3 expression was determined on NK cells by flow cytometry. Data are summarized from 4 different donors. (D)Primary human NK cells were pre-treated without or with IL2 (150 IU/ml) overnight and then co-cultured with K562 cells at an E/T ratio of 1:1, followed by analysis of TYRO3 expression on NK cells by flow cytometry. Data are summarized from 7 different donors. (E) NK cells in (D) were divided into CD56bright and CD56dim NK-cell subsets. Representative flow cytometry plots and summary data of TYRO3 expression in these two subsets from 7 different donors are shown. One-way ANOVA was used for B, D and E. P values were adjusted by the Holm-Sidak’s method. *, P<0.05; **, P<0.01; ****, P<0.0001. Data are presented as mean ± SD.