{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"CD14 is a component of the innate immune system. CD14 exists in two forms: either anchored into the membrane by a glycosylphosphatidylinositol tail (mCD14) or appearing in a soluble form (sCD14). CD14 acts as a co-receptor (along with the Toll-like receptor TLR 4 and MD-2) for the detection of bacterial lipopolysaccharide (LPS). CD14 can only bind LPS in the presence of lipopolysaccharide-binding protein (LBP). Although LPS is considered its main ligand, CD14 also recognizes other pathogen-associated molecular patterns (PAMPs).\nmCD14 is expressed on macrophages, monocytes, and some granulocytes. sCD14 is secreted by the liver and monocytes, and is sufficient in low concentrations to confer LPS-responsiveness to cells which otherwise do not express CD14. sCD14 that is produced by mammary epithelial cells is also present in human milk, where it is believed to regulate microbial growth in the infant gut."}]}]}