Lactoferrin and its biological functions.

Lactoferrin, a component of mammalian milk, is a member of the transferrin family. These glycoproteins transfer Fe(3+) ions. Lactoferrin is a unique polyfunctional protein that influences cell proliferation and differentiation. It can regulate granulopoiesis and DNA synthesis in some cells. Lactoferrin inhibits prostaglandin synthesis in human milk macrophages and activates the nonspecific immune response by stimulating phagocytosis and complement. It can interact with DNA, RNA, proteins, polysaccharides, heparin-like polyanions, etc.; in some of its effects, lactoferrin is found in complexes with ligands. It was recently demonstrated that lactoferrin also possesses ribonuclease activity and is a transcription factor. The list of known biological activities of lactoferrin is constantly increasing. This review analyzes possible mechanisms of its polyfunctionality.