Anne Jaekel and Robert B. Sim
MRC Immunochemistry Unit, Department of Biochemistry, University of Oxford, UK
Department of Pharmacology, University of Oxford, UK
Journal of Unsolved Questions, 2, 2, Articles 12-18, 2012 (Received Nov. 21st 2011, accepted Jan. 19th 2012, published online Feb. 18th, 2012)
The lung surfactant collectin proteins SP-A and SP-D have been shown to interact with phagocytic cells, such as macrophages and dendritic cells to facilitate uptake of pathogens and apoptotic cells. However, the mechanism by which the collectins interact with the phagocytes and which surface molecules on the phagocytic cells are involved is not yet clear. In the present study, we demonstrate the interaction of SP-A and SP-D with phagocytic cells including human monocyte-derived macrophages and immature dendritic cells. Results show that both proteins bind in a similar manner to both cell types. A prominent 20-22 kDa doublet band was observed on SDS- PAGE analysis as the major Ca2+ -dependent ligand for SP-A and SP-D on both macrophages and dendritic cells. However, we were unable to identify the proteins involved.