Lactoferrin: A protein of the innate immune system capable of killing parasitic protozoa

Lactoferrin (LF) is a cationic iron-binding glycoprotein found in mucosal secretions and fluids of mammals such as those from respiratory, vaginal, digestive and intestinal tract, tears and saliva and is particularly abundant in colostrum and milk. LF is also produced by the secondary granules of neutrophils and secreted by these cells in blood and sites of infection. This glycoprotein of about 80 kDa is a component of the innate immune system devoted to capture ferric iron in order to be unavailable for pathogens growth when they try to colonize and invade a host. LF is truly a multifunctional molecule since is immunomodulator, anti-carcinogenic and microbicidal. The iron-free form of LF (apoLF) is active against numerous infective species of bacteria, fungi, virus, and protozoa. LF is digested by the gastric enzyme pepsin, producing N-terminal peptides named Lactoferricins (LFcins), which often are more potent antimicrobials than the native protein. Milk-derived bovine LF as well as the recombinant human and bovine LF has been utilized to treat microbial infections in animal models and in trials with patients, resulting in an excellent option to treat several diseases. The research about LF in the treatment of parasitic diseases is limited; however, it is an exciting field of investigation, given the high morbidity and mortality rate produced by parasites, especially in developing countries, and also by the high number of resistance strains to commonly used drugs. In this chapter, we review the use of apoLF and LFcins to combat diseases caused by parasites and the known mechanisms involved in the action of LF on the parasitic cell and the immune status of the host.