Surfactant: Surfactant Protein D (SP-D)

Surfactant-associated protein D (SP-D) is a collagenous carbohydrate binding glycoprotein (collectin) that plays important roles in the lung's innate immune response to microbial and antigenic challenge. SP-D enhances the neutralization and/or clearance of a wide variety of microorganisms and microbial products, organic particulate antigens, and apoptotic cells, while inhibiting deleterious inflammatory and immune host responses. SP-D also contributes to the regulation of surfactant homeostasis, in part by reorganizing surfactant lipids, with resulting effects on epithelial uptake and turnover. Thus, it is likely that SP-D plays important roles in the pathogenesis of a wide variety of infectious, inflammatory, and immune-mediated lung disorders.