title: Evidence that exogenous substances can be phagocytized by alveolar epithelial cells and transported into blood capillaries.
abstract: Since the ability of alveolar epithelial cells to ingest inhaled fine particles has not been characterized in detail, the present study seeks to evaluate this physiological activity. We used a 0.2% suspension of intact or lecithin-coated polystyrene latex beads (240 nm in diameter). A 5-ml suspension of intact or lecithin-coated latex beads was intratracheally administered to rats using a compressor nebulizer. Thereafter, the lungs were perfused intratracheally with glutaraldehyde solution and cut into small pieces. The samples were postfixed with osmium tetroxide, embedded in epoxy resin and examined under an electron microscope. Both lecithin-coated and uncoated beads were incorporated into alveolar macrophages. Some of the ingested beads in the alveolar macrophages were sequestered within lysosomes. Types I and II alveolar epithelial cells selectively incorporated only lecithin-coated beads, which were also observed within the cytoplasm of monocytes in the capillary lumen. These findings suggest that alveolar epithelial cells can incorporate exogenous particles, which are then transferred from the alveoli to intravascular spaces by transcytosis.
authors.affiliation: Division of Pulmonary Medicine, Department of Medicine, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi-machi, Kawachi-gun, Tochigi, 329-0498, Japan. tomoko@jichi.ac.jp
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kato
authors.forename: Takashi
authors.initials: T
authors.lastname: Yashiro
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Murata
authors.forename: Damon C
authors.initials: DC
authors.lastname: Herbert
authors.forename: Katsuhisa
authors.initials: K
authors.lastname: Oshikawa
authors.forename: Masashi
authors.initials: M
authors.lastname: Bando
authors.forename: Shoji
authors.initials: S
authors.lastname: Ohno
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Sugiyama
mesh_terms: D000818:Animals; D002196:Capillaries / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism* / Q000648:ultrastructure; D016676:Macrophages, Alveolar / Q000378:metabolism; D008297:Male; D008854:Microscopy, Electron; D008863:Microspheres; D009330:Nebulizers and Vaporizers; D010587:Phagocytosis / Q000502:physiology*; D010713:Phosphatidylcholines / Q000493:pharmacokinetics; D011137:Polystyrenes / Q000493:pharmacokinetics*; D011650:Pulmonary Alveoli / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020545:Respiratory Mucosa / Q000166:cytology / Q000378:metabolism*; D013047:Specific Pathogen-Free Organisms
chemical_list: D010713:Phosphatidylcholines; D011137:Polystyrenes; C024075:styrofoam