CELLULAR EXPRESSION OF CERULOPLASMIN IN BABOON AND MOUSE LUNG DURING DEVELOPMENT AND INFLAMMATION

Ceruloplasmin (CP) is an important extracellular antioxidant and free radical scavenger. Although CP is expressed mainly in the liver, recen t studies have identified the lung as another major site of CP synthes is. The sites and cell types that are responsible for CP expression in baboon and mouse lung are described. CP mRNA is detected in primordia l bronchial epithelium in baboon fetuses by 60 days of gestation. At 1 40 days of gestation and thereafter, CP mRNA is found in airway epithe lium and in the ductal cells of the submucosal glands. In developing a nd mature mice, CP mRNA is present in epithelial cells throughout the airway. In endotoxin-treated mice, the amount of CP mRNA increases sev eral-fold in large airways but increases only moderately in small airw ays. This suggests that the high concentration of CP in the mucus lini ng of the upper airway, which serves to filter harmful substances, is particularly important during stressful conditions. Endotoxin treatmen t in mice also results in the induction of high levels of CP mRNA in a subset of alveolar wall cells. The data suggest that the airway epith elial cells are the major source of CP in the lung fluid and support c eruloplasmin's critical role in host defense against oxidative damage and infection in the lung.