Effect of feeding whey peptide fractions on the immune response in healthy and Escherichia coli infected mice

The antimicrobial and immunomodulatory activities of whey proteins and peptides make them promising candidates for protection against pathogens. To test this hypothesis, a whey protein isolate and three peptide fractions obtained from its trypsin/chymotrypsin digestion were given orally to mice for 7 days. Half the mice were then infected with Escherichia coli O157:H7 and serum cytokines and total immunoglobulin A (IgA) were measured over the next 7 days. All whey products strongly stimulated total IgA production in non-infected mice, suggesting a potential adjuvant role. The peptide fractions produced contrasting immunomodulatory effects: the neutral fraction (4.5 < pH < 7) stimulated serum interferon-gamma (IFN-γ), whereas the acidic fraction (pH < 4.5) inhibited it. In the infected model, only the basic fraction (pH > 7) induced a sustained serum IgA secretion, which coincided with increased transforming growth factor-beta 1 (TGF-β1) levels. These results indicate that some whey peptides modulate immune parameters in healthy mice, whereas the basic peptide fraction increased immune vigilance during the infection.