Role of alveolar macrophages on the long-term clearance of nanoparticles from the peripheral lungs

Rationale: While the rate determining role of alveolar macrophages (AM) on phagocytosis and clearance of deposited micron-sized particles (MP) is well documented in the literature, there are clear indications that AM phagocytosis of deposited nanoparticles (NP) in the periphery is rather limited. Methods & Results: Based on our comprehensive and quantitative biokinetics studies up to six months after 1-h-short-term inhalation of 20nm iridium and titanium dioxide NP we confirmed that the phagocytised fraction of NP after 24 hours is about 25% of the peripherally deposited NP. The vast majority (˜75% of total lung…