NK cell immunophenotyping and activation assay of SM patients. (A) Six SM patients with AHN (n = 3) and without AHN (n = 3) were compared with 7 normal donors by flow cytometry. (B) CD107a, (C) IFN-γ, and (D) TNF-α expression of NK cells was measured against K562 (left), HL-60 (center), and ROSA^{KIT D816V} (right) target cells with noted treatment after 4-hour incubation. *P ≤ .05; **P < .01; ***P < .001. Red bars, normal donors; blue bars, SM patients.