Surfactant Protein A2 Gene Expression by Human Airway Submucosal Gland Cells

To determine whether human airway submucosal glands produce and secrete surfactant proteins, we examined their protein and gene expression in submucosal glands from trachea and bronchi obtained from operated and autopsied lungs within 4 h of death. Using a monoclonal antibody (PE-10) against surfactant protein A (SP-A), a positive immunoperoxidase stain was observed over serous cells of submucosal glands in histologic sections of airway walls. Measurement of SP-A in culture medium samples using single-step enzyme-linked immunosorbent assay showed a significant secretion of SP-A by isolated submucosal glands (1.2 ± 0.08 ng/ml/h, SEM, n = 40). In gene expression experiments by reverse transciption-polymerase chain reaction, the SP-A complementary DNA (cDNA) segment was amplified from isolated submucosal glands, indicating the presence of SP-A messenger RNA (mRNA) in airway submucosal glands. Bronchial superficial epithelial cells failed to show the presence of SP-A mRNA. No cDNA segment of SP-B, SP-C, or SP...