title: Presence of apocrine epithelial antigen (AEA) in type II pneumocytes and in hyaline membranes of neonatal RDS.
abstract: We have investigated the distribution of an apocrine membrane antigen (AEA) in pulmonary tissue using a rabbit antiserum raised against fat globule glycoproteins isolated from human milk. In indirect immunostaining (PAP, IF) of sections from normal lung tissue, the membranes facing the alveolar lumen of cells corresponding to the type II pneumocytes in the alveolar walls were decorated. The selective distribution of AEA to the membranes of type II pneumocytes was confirmed in double immunostaining by identification of these cells with rat antibodies against surfactant apoprotein. In fetal lung tissue, the AEA antigen was detected by the 9th week of gestation. In lung samples from newborns which had died of respiratory distress syndrome (RDS) the intra-alveolar hyaline membranes stained for the AEA antigen. SDS-PAGE of the immunoprecipitate obtained with anti-AEA serum from radiolabelled glycoprotein fraction of normal lung tissue revealed a single band of 79,000 dalton apparent molecular weight. These findings indicate that the AEA constitutes a membrane marker of the type II pneumocytes and might be involved in the secretory process of surfactant. Immunohistological evidence for the presence of AEA in the hyaline membranes of neonatal RDS is also presented.
mesh_terms: D000941:Antigens / Q000032:analysis*; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000276:immunology*; D008565:Membrane Proteins / Q000032:analysis*; D008566:Membranes / Q000032:analysis; D018396:Mucin-1; D011650:Pulmonary Alveoli / Q000473:pathology; D011663:Pulmonary Surfactants / Q000032:analysis; D012127:Respiratory Distress Syndrome, Newborn / Q000276:immunology*
chemical_list: D000941:Antigens; D008565:Membrane Proteins; D018396:Mucin-1; D011663:Pulmonary Surfactants