Pulmonary Surfactant-Associated Proteins: Proteins found in the LUNG that act as PULMONARY SURFACTANTS.Proteolipids: Protein-lipid combinations abundant in brain tissue, but also present in a wide variety of animal and plant tissues. In contrast to lipoproteins, they are insoluble in water, but soluble in a chloroform-methanol mixture. The protein moiety has a high content of hydrophobic amino acids. The associated lipids consist of a mixture of GLYCEROPHOSPHATES; CEREBROSIDES; and SULFOGLYCOSPHINGOLIPIDS; while lipoproteins contain PHOSPHOLIPIDS; CHOLESTEROL; and TRIGLYCERIDES.Pulmonary Surfactants: Substances and drugs that lower the SURFACE TENSION of the mucoid layer lining the PULMONARY ALVEOLI.Pulmonary Surfactant-Associated Protein A: An abundant pulmonary surfactant-associated protein that binds to a variety of lung pathogens, resulting in their opsinization. It also stimulates MACROPHAGES to undergo PHAGOCYTOSIS of microorganisms. Surfactant protein A contains a N-terminal collagen-like domain and a C-terminal lectin domain that are characteristic of members of the collectin family of proteins.Pulmonary Surfactant-Associated Protein C: A pulmonary surfactant associated protein that plays a role in alveolar stability by lowering the surface tension at the air-liquid interface. It is a membrane-bound protein that constitutes 1-2% of the pulmonary surfactant mass. Pulmonary surfactant-associated protein C is one of the most hydrophobic peptides yet isolated and contains an alpha-helical domain with a central poly-valine segment that binds to phospholipid bilayers.Pulmonary Surfactant-Associated Protein B: A pulmonary surfactant associated-protein that plays an essential role in alveolar stability by lowering the surface tension at the air-liquid interface. Inherited deficiency of pulmonary surfactant-associated protein B is one cause of RESPIRATORY DISTRESS SYNDROME, NEWBORN.Pulmonary Surfactant-Associated Protein D: An abundant pulmonary surfactant-associated protein that binds to a variety of lung pathogens and enhances their opsinization and killing by phagocytic cells. Surfactant protein D contains a N-terminal collagen-like domain and a C-terminal lectin domain that are characteristic of members of the collectin family of proteins.1,2-Dipalmitoylphosphatidylcholine: Synthetic phospholipid used in liposomes and lipid bilayers to study biological membranes. It is also a major constituent of PULMONARY SURFACTANTS.Lung: Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.Pulmonary Alveoli: Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place.Bronchoalveolar Lavage Fluid: Washing liquid obtained from irrigation of the lung, including the BRONCHI and the PULMONARY ALVEOLI. It is generally used to assess biochemical, inflammatory, or infection status of the lung.Glycoproteins: Conjugated protein-carbohydrate compounds including mucins, mucoid, and amyloid glycoproteins.