Time course of hemosiderin production and clearance by human pulmonary macrophages.

Tracheal aspirates from four previously healthy infants with acute pulmonary hemorrhage, and small volume bronchial lavages from children undergoing flexible fiberoptic bronchoscopy were examined for pulmonary alveolar macrophages (PAM) containing hemosiderin. Hemosiderin formation was also studied in vitro. Macrophages containing hemosiderin were first seen in tracheal aspirates 50 hours after an acute pulmonary hemorrhage and after 72 hours in cultured macrophages. A small percentage of the PAM recovered by bronchoalveolar lavage from both adults and children contained hemosiderin. Hemosiderin was rapidly cleared from the lungs following an acute pulmonary hemorrhage.