Expression of HIF-2α is up-regulated in neutrophils from patients with active inflammatory arthritis and is seen in neutrophils within lung biopsies from patients with COPD. (A) Expression of HIF1A and HIF2A in inflammatory arthritis patients (filled bars) and controls (open bars) was determined by TaqMan analysis of cDNA from freshly isolated peripheral blood neutrophils with data normalized to ACTB expression. Data are mean and SEM for n = 4. (B-C) HIF-2α protein expression is significantly higher in neutrophils from patients with inflammatory arthritis (IA) than healthy volunteers (HV). Freshly isolated neutrophils were lysed and proteins separated by SDS-PAGE. Blots were probed for HIF-2α, and densitometry data were normalized to p38 MAPK. (B) Data are mean and SEM for n = 3. (C) HIF-2α blots of circulating neutrophil lysates from 3 healthy volunteers (HV) and 3 patients with inflammatory arthritis (IA). (D-H) Immunohistochemistry showing HIF-2α expression in lung biopsies from a (E) nonsmoker and patients with (F) mild or (G-H) severe COPD. Images are representative of n = 2. D is a section stained with an isotype control. Original magnification: (D-G) ×200; (H) ×1000.