Defective NK-cell activation and cytolytic activity in response to IL-15 in cells from a STAT1-deficient patient. (A) Activated NK cells derived from a healthy subject or from the STAT1-deficient patient were deprived from IL-2 for 16 hours and then preincubated with IFN-α (104 U/mL) for 48 hours and stimulated with IL-15 (100 ng/mL) or medium alone for 20 minutes. STAT1 phosphorylation of IL-15–stimulated NK cells was assessed by intracellular staining with anti-phospho-STAT1-PE mAb. Mean fluorescence intensity is indicated. The results are representative of 3 independent experiments. (B) Activated NK cells from patient and healthy control were IL-2 deprived for 16 hours and then stimulated with IL-2 (100 ng/mL) and IL-15 (100 ng/mL) or medium alone for 20 minutes. STAT5 phosphorylation was assessed by intracellular staining with anti-phospho-STAT5-PE mAb. Mean fluorescence intensity is indicated. The results are representative of 3 independent experiments. (C) Activated NK cells derived from a healthy subject or from the STAT1-deficient patient were stimulated with IL-12 (10 ng/mL), IL-15 (100 ng/mL), IL-18 (100 ng/mL), and with a combination of IL-12 and IL-15, or IL-12 and IL-18 or medium alone in the presence of the target cell line K562. The intracellular expression of IFN-γ by NK cells of the healthy subject (black bar) or of the patient (gray bar) are shown as the percentage of IFN-γ–positive cells. Data are mean ± SE. *Significant difference in the response between the patient and control the subject (P < .05).
