Transferrins are iron binding transport proteins which can bind two Fe3+ ions in association with the binding of an anion, usually bicarbonate. Lactoferrin is a member of the transferrin family and is a major iron-binding and multifunctional protein found in exocrine fluids such as breast milk and mucosal secretions. High levels of Lactoferrin are found in saliva and tears, intermediate levels in serum and plasma, and low levels in urine. The canonical sequence of Lactoferrin (known as isoform 1) is 710 amino acids in length and runs at 78.2 kDa. Isoform Delta-Lactoferrin (or DeltaLF) is missing amino acids 1 – 44 of the canonical sequence. Mouse and rat Lactoferrin are 71% and 62% identical to human Lactoferrin, respectively.

Lactoferrin possesses antibacterial, antiviral, anti-inflammatory, and immunoregulatory properties. The presence of Lactoferrin in neutrophils and the release of Lactoferrin during inflammation suggest that Lactoferrin is involved in phagocytic killing and immune responses. Additionally, Lactoferrin mediates bacteriostasis through its ability to sequester free iron and inhibit microbial growth. Lactoferrin also directs bactericidal properties leading to the release of lipopolysaccharides from the bacterial outer membrane. Furthermore, Lactoferrin may play a role in the regulation of bone growth because it has anabolic, differentiating, and anti-apoptotic effects on osteoblasts and can also inhibit osteoclastogenesis. Salivary Lactoferrin plays an important role in protecting the oral cavity against several oral pathogens including Streptococcus mutans. Additionally, increased levels of Lactoferrin in fecal samples is used as a marker of active inflammatory bowel disease (IBD).