Impaired IFN-γ response in a STAT1-deficient patient. (A) Monocytes of a patient and a healthy subject were stimulated in vitro for 48 hours with IFN-γ (100 ng/mL), LPS (100 ng/mL), and with a combination of IFN-γ and LPS or medium alone. Target gene expression was normalized to the housekeeping gene (GAPDH) expression and presented as n-fold of the expression in unstimulated cells from the healthy control. The experiments shown are representative of 3 independent experiments. Data are mean ± SE. *Significant difference in the response between the patient and the control subject (P < .05). (B) PBMCs (2 × 10⁶/mL) from the patient or a healthy control were stimulated with IFN-γ (50, 100, 200, 500 ng/mL) for 48 hours. The production of TNF-α in the supernatant was determined by ELISA. (C) EBV-transformed B cells from the patient and a healthy subject were stimulated in vitro with the indicated doses of IFN-γ for 24 hours. Target gene expression was normalized against the housekeeping gene (EBNA1) and presented as n-fold increase over the expression in unstimulated cells from the healthy control. (D-E) PBMCs from the patient and a healthy subject were cultured with RPMI 1640 supplemented with 10% FBS and stimulated in vitro for 48 hours (D) or for 24 hours with IFN-γ (100 ng/mL; E). Target gene expression was normalized to the housekeeping gene (β2M) expression and presented as n-fold of the expression in unstimulated cells from the healthy control. The experiments shown are representative of 4 independent experiments. Data are mean ± SE. *Significant difference in the response between the patient and control subject (P < .05).