Endotoxemia Enhances Pulmonary Mononuclear Cell Uptake of Circulating Particles and Pathogens in a Species Without Pulmonary Intravascular Macrophages

Abstract

Pulmonary intravascular macrophages (PIMs) are large mature macrophages that adhere to the endothelium of pulmonary capillaries in selected species. They have morphologic features characteristic of differentiated macrophages, and thus, are not simply adherent circulating monocytes. For example, they have abundant phagocytic vacuoles and have been shown to avidly ingest intravenously injected particles such as magnetic iron oxide particles or colloidal gold. 1 Warner AE Brain JD The cell biology and pathogenic role of pulmonary intravascular macrophages. Am J Physiol. 1990; 258: L1-L2 PubMed Google Scholar These PIMs also form unusual adhesive complexes with the membrane of underlying capillary endothelial cells. These adhesion complexes are similar in all species studied and include a 12 to 15 nm intercellular space and subplasmalemmal electron density in both cell types. 1 Warner AE Brain JD The cell biology and pathogenic role of pulmonary intravascular macrophages. Am J Physiol. 1990; 258: L1-L2 PubMed Google Scholar