Lactotransferrin

Lactotransferrin (LTF) is a globular multifunctional protein with antimicrobial activity (bacteriocide, fungicide), is part of the innate defense, mainly at mucoses. LTF is found in milk and many mucosal secretions such as tears and saliva. LTF is also present in secondary granules of PMN and also is secreted by some acinar cells. LTF can be purified from milk or produced recombinantly. Human colostrum has the highest concentration, followed by human milk, then cow milk.

Structure
LTF belongs to the transferrin family proteins (TF, melanotransferrin, ovotransferin, etc.). Its molecular mass is 80,000 u (80 kDa).

Function
LTF antimicrobial activity is due partly to its high affinity for Fe (ferric state). LTF proteolysis produces lactoferricin, kaliocin-1 small peptides with antimicrobial activity.

LTF receptors have been found on brush-border cells, PMN, monocytes, Mφ and activated lymphocytes.