Lactoferrin is a globular glycoprotein with a molecular mass of about 80 kDa that is widely represented in various secretory fluids, such as milk, saliva, tears, and nasal secretions.

[5] Lactoferrin is one of the components of the immune system of the body; it has antimicrobial activity (bacteriocide, fungicide) and is part of the innate defense, mainly at mucoses.

Lactoferrin supplements reduce the risk of respiratory tract infections, based on a recent meta-analysis of randomized controlled trials.

They documented the molecular weight, isoelectric point, optical absorption spectra and presence of two iron atoms per protein molecule.

Deletions, insertions and mutations of stop codons affect the coding part and its length varies between 2,055 and 2,190 nucleotide pairs.

There are differences in amino acid sequences: 8 in Homo sapiens, 6 in Mus musculus, 6 in Capra hircus, 10 in Bos taurus and 20 in Sus scrofa.

Similarity in the size of exons and their distribution in the domains of the protein molecule indicates that the evolutionary development of lactoferrin gene occurred by duplication.

N-lobe corresponds to amino acid residues 1-333 and C-lobe to 345-692, and the ends of those domains are connected by a short α-helix.

This facilitates the transfer of iron from transferrin to lactoferrin during inflammations, when the pH of tissues decreases due to accumulation of lactic and other acids.

Both in blood plasma and in secretory fluids lactoferrin can exist in different polymeric forms ranging from monomers to tetramers.

In particular, by destroying the RNA genome, milk RNase inhibits reverse transcription of retroviruses that cause breast cancer in mice.

[32] Parsi women in West India have the milk RNase level markedly lower than in other groups, and their breast cancer rate is three times higher than average.

[38] Lactoferrin's primary role is to sequester free iron, and in doing so remove essential substrate required for bacterial growth.

[40] Although lactoferrin also has other antibacterial mechanisms not related to iron, such as stimulation of phagocytosis,[41] the interaction with the outer bacterial membrane described above is the most dominant and most studied.

Iron-free apolactoferrin is more efficient in this function than hololactoferrin; and lactoferricin, which is responsible for antimicrobial properties of lactoferrin, shows almost no antiviral activity.

[61] Lactoferrin and lactoferricin inhibit in vitro growth of Trichophyton mentagrophytes, which are responsible for several skin diseases such as ringworm.

[62] Lactoferrin also acts against the Candida albicans – a diploid fungus (a form of yeast) that causes opportunistic oral and genital infections in humans.

[63] Administration of lactoferrin through drinking water to mice with weakened immune systems and symptoms of aphthous ulcer reduced the number of Candida albicans strains in the mouth and the size of the damaged areas in the tongue.

[65] Oral administration of lactoferrin to animals also reduced the number of pathogenic organisms in the tissues close to the gastrointestinal tract.

Candida albicans could also be completely eradicated with a mixture containing lactoferrin, lysozyme and itraconazole in HIV-positive patients who were resistant to other antifungal drugs.

[64][68] The anticancer activity of bovine lactoferrin (bLF) has been demonstrated in experimental lung, bladder, tongue, colon, and liver carcinogeneses on rats, possibly by suppression of phase I enzymes, such as cytochrome P450 1A2 (CYP1A2).

[78] Low quality evidence suggests that oral lactoferrin supplementation with or without the addition of a probiotic may decrease late onset of sepsis and necrotizing enterocolitis (stage II or III) in preterm infants with no adverse effects.

[80] A rapid, portable test utilizing microfluidic technology has been developed to enable measurement of lactoferrin levels in human tear fluid at the point-of-care with the aim of improving diagnosis of Sjögren's syndrome and other forms of dry eye disease.

[81] Bovine lactoferrin can be isolated from raw milk, colostrum, or whey using methods such as salt extraction, chromatography, and membrane filtration.