Lactoferrin, a key molecule in immune and inflammatory processes.

Lactoferrin (Lf) belongs to the family of antimicrobial molecules that constitute the principal defense line of nonvertebrate organisms. In human immunity, their roles are considerably extended, and actually exceed mere direct antimicrobial properties. As a result, Lf is involved in both innate and adaptive immunities where its modulating effects not only help the host fight against microbes but also protect the host against harmful effects of inflammation. Such beneficial effects have been noticed in studies using dietary Lf, without the experimenters always explaining the exact modes of action of Lf. Effects on mucosal and systemic immunities are indeed often observed, which make the roles of Lf tricky to decipher. It is now known that the immunomodulatory properties of Lf are due to its ability to interact with numerous cellular and molecular targets. At the cellular level, Lf modulates the migration, maturation, and functions of immune cells. At the molecular level, in addition to iron binding, interactions of Lf with a plethora of compounds, either soluble or cell-surface molecules, account for its modulatory properties. This paper reviews our current understanding of the mechanisms that explain the regulatory properties of Lf in immune and inflammatory processes.