Fig. 4. Oxidative stress promotes the expression of IRF3 and IRF5. PBMC were treated with H₂O₂ for induction of oxidative stress or with vehicle (mock). Total RNA was extracted, and IRF3/5 gene expression was determined using real-time RT-PCR as described in materials and methods. At the same time, harvested cells were also stained intracellularly to assess the IRF3/5 protein expression (Staining Index) by flow cytometry. The data (mean±SEM) obtained from 5 independent determinations with similar results show the increased IRF3 expression (P<0.05) in H₂O₂-treated PBMC at: (A) mRNA (4.0±0.31 fold); and (B) protein (SI=2.50) levels compared to respective controls (mock). Similarly, H₂O₂ treatment enhanced the IRF5 expression (P<0.05) in PBMC at: (C) mRNA (1.60±0.06 fold); and (D) protein (SI=1.48) levels compared to respective controls (mock).