Surfactant Protein D Binds Genomic DNA and Apoptotic Cells, and Enhances Their Clearance, in Vivo

: Collectins, such as surfactant protein D (SP‐D), bind apoptotic cells; however, the ligands that they recognize on these cells are unknown. We hypothesized that SP‐D binds to the DNA present on these cells. We show that SP‐D binds and aggregates mouse alveolar macrophage DNA effectively. Alveolar macrophages of SP‐D(−/−) mice contained more nicked DNA than those of SP‐A(−/−) and wild type mice. Our results also suggest that carbohydrate recognition domains of SP‐D may recognize DNA present on the apoptotic cells. Therefore, cell‐surface DNA could be a ligand for recognition of apoptotic cells by collectins.