Table 4.

MFGM proteins and lipids involved in the infant intestinal immune system.

MFGM protein	Functions
α-lactalbumin	Proteolysis of α-lactalbumin generates peptides with bactericidal or immune-stimulatory activities (164, 165). Protects against diarrhea caused by enteropathogenic Escherichia coli (166).
Butyrophilin subfamily 1 member A1 (BTN1A1)	Involved in the regulation of lipid secretion (167). Involved in T-cell proliferation and metabolism (168).
Human leukocyte antigen II (HLAII)	May present maternal antigens to infant T-cells (169–171).
Lactadherin (PAS VI/VII, MFG-E8)	Regulates apoptosis by phagocytes (127, 172). Induces anti-inflammatory responses (173). Regulates T-cell proliferation and cytokine production profile by dendritic cells (173). Involved in the protective effect against rotavirus (119, 174).
Lysozyme	Inhibits the growth of Gram-negative bacteria by disrupting the outer membrane and cooperating with lactoferrin (175).
Mucin-1 (MUC1)	Binds to microorganisms and chemicals to prevent infection and inflammation (176). Inhibits the growth of Salmonella enterica serovar Typhimurium (177), S-fimbriated Escherichia coli (178), and rotavirus (179). Suppresses inflammation caused by Pseudomonas aeruginosa and its flagellin by down-regulating Toll-like receptor pathways (180, 181).
Osteopontin (OPN)	Binds to Streptococcus agalactiae and Staphylococcus aureus, enhancing phagocytosis by macrophages (162). Induces Th1 immune response (elevating IL-12 production from the macrophages) while suppressing the Th2 immune response (reducing IL-10 secretion) [162)].
Xanthine oxidoreductase (XOR)	Generates reactive oxygen species with antibacterial properties (182).
Gangliosides	Regulates activity and functionalities of immune cells including lymphocytes and dendritic cell, playing a role in developing immune tolerance (41).