Laktoferrin

Laktoferrin (lactoferrin) is a glycoprotein of the transferrin family that occurs in various mammalian secretions and blood cells. It binds ferric iron (Fe3+) reversibly, existing in iron-free (apo) and iron-saturated (holo) forms. It is most abundant in human milk and colostrum but is also found in other secretions such as tears, saliva, nasal mucus, and in neutrophil granules.

Structurally, lactoferrin is an approximately 80 kDa protein composed of two lobes that can each bind one iron ion. It is highly conserved across mammalian species and is a glycoprotein with carbohydrate chains that influence its stability and interactions.

Function and mechanism: By sequestering iron, lactoferrin limits growth of iron-dependent microorganisms, contributing to antimicrobial activity. It can also act directly on microbes by binding to surfaces and disrupting membranes, and it interacts with components such as lipopolysaccharide. In the immune system, lactoferrin modulates inflammation and immune cell activity, influencing cytokine release, phagocytosis, and mucosal barrier function. It also has antioxidant effects by reducing free iron-catalyzed oxidative stress.

Clinical and practical relevance: Lactoferrin is used as an ingredient in some infant formulas and dietary supplements and is studied for prevention and treatment of infections and inflammatory diseases. Evidence for specific clinical benefits is mixed, and it is not a cure for disease. For safety, lactoferrin from milk sources is generally well tolerated in appropriate amounts, though dairy allergies or intolerances may apply, and recombinant or highly purified preparations may have distinct regulatory statuses.