In the bronchoalveolar space this critical balance is maintained by innate immune proteins, termed surfactant proteins. Among these, surfactant protein D (SP-D) plays a central role in the pulmonary host defence and the modulation of allergic responses.Click to see full answer. Similarly one may ask, what is surfactant protein D?In molecular biology, Pulmonary surfactant protein D (SP-D) is a protein domain predominantly found in lung surfactant. This protein plays a special role; its primary task is to act as a defence protein against any pathogens that may invade the lung.Secondly, what is surfactant and how does it work? Surfactants are compounds that lower the surface tension (or interfacial tension) between two liquids, between a gas and a liquid, or between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants. Also asked, what is the role of surfactant in the lungs? Pulmonary surfactant is a mixture of lipids and proteins which is secreted by the epithelial type II cells into the alveolar space. Its main function is to reduce the surface tension at the air/liquid interface in the lung. Surfactant protein A (SP-A) appears to promote most of SP-B’s functions.How does surfactant prevent pulmonary edema?Alveolar edema inactivates surfactant, and surfactant depletion causes edema by reducing lung interstitial pressure (Pis). We conclude that surfactant normalizes surface tension and decreases transcapillary hydrostatic forces in this lung injury model, thereby reducing edema formation and improving gas exchange.