In vitro inhibition of mammary cell growth by lactoferrin: a comparative study.

The effect of lactoferrin (Lf) on mammary epithelial cell growth in culture was tested in a comparative study of bovine and human Lf. Bovine Lf was inhibitory to growth of a bovine mammary epithelial cell line, both in the presence and absence of fetal bovine serum in the medium. The growth inhibition activity of bovine Lf was not affected by iron-saturation status of the protein. In contrast with bovine Lf, human Lf had minimal inhibitory activity on bovine cell growth in the presence of serum, and cell growth was stimulated by human Lf in the absence of serum. In the latter case, human Lf may have acted as an iron-transport protein for the cells. Bovine Lf and human Lf had no effect on growth of MCF-7 human breast tumor cells and only minimal inhibitory activity toward the MDA-MB 231 human breast tumor cell line. The effect of bovine Lf on bovine mammary epithelial cells could be prevented by immunoneutralization of the Lf. These results indicate that Lf can be inhibitory to growth of mammary epithelial cells in culture, but this response to specific for the species origin of the Lf and of the mammary cell.