title: Subpopulations of human lung alveolar macrophages: ultrastructural features.
abstract: Lung alveolar macrophages (LAM), obtained by bronchoalveolar lavage of healthy donors, were separated into four subfractions on discontinuous gradients of Percoll and subjected to light microscopic, transmission (TEM) and scanning electron microscopic (SEM) studies. Alveolar macrophage morphometric analysis was performed on cytocentrifuged preparations. TEM of subpopulations revealed considerable morphologic heterogeneity. By SEM, cells of the most dense (D) subfraction were small, round, and, typically, the surface was highly ruffled with small membrane pseudopods. Cells of the least dense subfraction (A) showed a low degree of membrane folding or filopodia and were often totally disorganized. In smokers, macrophages of fraction A had a greater area and perimeter compared with non-smokers, whereas the inverse relationship was observed for C and D cells. Also, the number of electron-dense inclusions and the level of acid phosphatase were higher in smokers than in non-smokers. Coupled with functional heterogeneity the morphologic differences described in this paper suggest that density-separated subpopulations of LAM may represent different stages of differentiation or maturation.
authors.affiliation: Department of Pathology, Ullevaal Hospital, University of Oslo, Norway.
authors.forename: B
authors.initials: B
authors.lastname: Nakstad
authors.forename: T
authors.initials: T
authors.lastname: Lyberg
authors.forename: F
authors.initials: F
authors.lastname: Skjörten
authors.forename: N P
authors.initials: NP
authors.lastname: Boye
mesh_terms: D000328:Adult; D002469:Cell Separation / Q000379:methods; D002470:Cell Survival; D002498:Centrifugation; D006801:Humans; D008264:Macrophages / Q000145:classification* / Q000166:cytology / Q000648:ultrastructure; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000648:ultrastructure