Lactoferrin (LF), also known as lactotransferrin (LTF), is a multifunctional protein of the transferrin family. 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. In particular, lactoferrin provides antibacterial activity to human infants. Lactoferrin interacts with DNA and RNA, polysaccharides and heparin, and shows some of its biological functions in complexes with these ligands. LTF is known to activate immune cells to produce several cytokines, such as tumor necrosis factor TNF-a, thus, a stimulation assay was conducted to detect the activity of LTF using human monocytic cell line THP-1. Briefly, THP-1 cells were seeded into wells of 24-well plates at a density of 5×106 cells/mL in RPMI-1640 with the addition of various concentrations of recombinant human LTF. After incubation for 20 hours, the concentration of TNF-a in the cell supernatant was detected using an ELISA kit. TNF-a levels in the cell supernatant of spleen cells increased significantly after stimulated with LTF, the data was shown in table 1.

Figure. TNF-a concentration in the cell supernatant of THP-1 cells up-regulated by LTF.