Factors in ruminant colostrum that influence cell growth and murine IgE antibody responses.

Bovine colostrum was investigated as a source of biologically active molecules capable of stimulating the growth of mammalian cells in culture and modifying the immune response in a murine model. An extract prepared from bovine colostral whey by cation exchange and reversed-phase chromatography stimulated the growth of L6 rat myoblasts, Balb/c-3T3 mouse fibroblasts and BHK-21 baby hamster kidney cells with equal or greater potency than fetal bovine serum. Fractionation of the bovine colostral extract by gel-permeation chromatography in M-acetic acid identified a number of cell-growth factors for each cell type. Bovine colostral extract was compared with an ovine colostral whey preparation for its ability to modulate IgE antibody responses in mice. Doses of 8 and 4 mg/d of ovine colostral whey or bovine colostral extract specifically suppressed IgE antibody responses, whereas at lower doses suppression did not occur. We conclude that bovine colostrum contains cell-growth factors as well as immunomodulatory factors that are able to regulate the IgE response in a heterologous species.