Localization of surfactant protein A (SP-A) in alveolar macrophage subpopulations of normal and fibrotic rat lung.
The colocalization of surfactant protein A (SP-A) and the alveolar macrophage markers ED1 and RM-1, as well as various lectins of the N-acetyl-galactosamine group [Maclura pomifera lectin (MPA), Dolichos biflorus lectin (DBA), soybean agglutinin (SBA)] and of the mannose group [Canavalia ensiformis lectin (ConA), Galanthus nivalis lectin (GNA)] was studied in normal and fibrotic rat lung tissues. In normal tissue, SP-A was located preferentially in the alveolar macrophage subpopulation lacking specific binding sites for lectins of the N-acetylgalactosamine group (DBA and SBA), although 50% of MPA-binding macrophages contained SP-A. The ED1-positive cells were SP-A-negative, whereas SP-A uptake could be detected among the RM-1 immunoreactive as well as the ConA and GNA binding macrophages. In fibrotic lung tissue, however, a small number of DBA and SBA binding macrophages contained SP-A and the percentage of GNA and ConA binding alveolar macrophages exhibiting SP-A immunoreactivity was reduced. Additionally, the number of ED1+/SP-A+ macrophages was found to be increased. Immunoelectron microscopy revealed accumulation of SP-A in the extracellular space. The differing SP-A content in different alveolar macrophage subpopulations suggests a more complex mechanism of uptake and degradation of surfactant proteins in normal and pathological conditions, which cannot simply be explained by the glycoconjugate pattern on the surface of alveolar macrophages.
Kasper
M
M
Institute of Pathology, Technical University of Dresden, Germany.
Sakai
K
K
Koslowski
R
R
Wenzel
K W
KW
Haroske
G
G
Schuh
D
D
Müller
M
M
D000818:Animals; D001761:Bleomycin; D005260:Female; D027801:Galanthus; D006023:Glycoproteins / Q000032:analysis* / Q000378:metabolism; D007150:Immunohistochemistry; D037102:Lectins / Q000378:metabolism; D008168:Lung / Q000737:chemistry* / Q000187:drug effects / Q000528:radiation effects; D016676:Macrophages, Alveolar / Q000737:chemistry* / Q000166:cytology / Q000187:drug effects; D016253:Microscopy, Immunoelectron; D008867:Microtomy; D037121:Plant Lectins; D011510:Proteolipids / Q000032:analysis* / Q000378:metabolism; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000032:analysis* / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D030262:Soybean Proteins; D016610:Tissue Embedding; D010835:Phytohemagglutinins
D001761:Bleomycin; D006023:Glycoproteins; D037102:Lectins; D037121:Plant Lectins; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D030262:Soybean Proteins; C036554:dolichos biflorus agglutinin; C028824:soybean lectin; D010835:Phytohemagglutinins