Metal-rich ambient particles (Particulate Matter2.5) cause airway inflammation in healthy subjects

Epidemiologic studies have shown an increased prevalence of allergic asthma in children living in a German smelter area (Hettstedt) compared with a cohort who live in a nonindustrialized area (Zerbst). However, it is not known whether ambient particles (particulate matter(2.5) [PM2.5]) from these areas induce distinct lung inflammation, which might be an explanation for this difference. Therefore, 100 mug of PM2.5 suspensions, collected simultaneously in the two areas, were instilled through a bronchoscope into contralateral lung segments of 12 healthy volunteers. PM2.5 from both Hettstedt and Zerbst increased the number of leukocytes in the bronchoalveolar lavage performed 24 hours later. PM2.5 from Hettstedt, but not Zerbst, induced a significant influx of monocytes (Hettstedt: 7.0% vs. Zerbst: 4.3%) without influencing the expression of surface activation markers on monocytes and alveolar macrophages. Oxidant radical generation of bronchoalveolar lavage cells and cytokine concentration (interieukin-6 and tumor necrosis factor-alpha) in bronchoalveolar lavage fluid was significantly increased after instillation of Hettstedt PM2.5. We conclude that environmentally relevant concentrations of PM2.5 from the smelter area induced distinct airway inflammation in healthy subjects with a selective influx of monocytes and increased generation of oxidant radicals. The higher concentration of transition metals in PM2.5 from Hettstedt might be responsible for this increased inflammation.