Factor Function
Humoral
Secretory IgA Immune exclusion, bactericidal activity, ,virus neutralization and prevention of bacterial adherence to epithelial cells [32].
sIgA Mannose glycans Inhibit the binding of Type1 fimbriated Escherichia coli to epithelial cells [30].
sIgA Fucose glycans Inhibit the binding of Enteropathogenic Escherichia coli to epithelial cells [30].
sIgA Fucose glycans Inhibit the binding of Helicobacter pylori to epithelial cells [30].
sIgA Sialicacid-containing glycans Inhibit the binding of S-fimbriated Escherichia coli to epithelial cells [30].
sIgA undefined glycans Inhibit the binding of Toxin A of Clostridium difficile to epithelial cells [30].
IgM Protection of infant against bacterial and viral infections [5].
IgG Protection of infant against allergic sensitization [19].
IgE Protection of infant against allergic sensitization [19].
IgD Inhibition of IgE-induced histamine release but not cytokine production by basophils [26].
Complement Constituents Bactericidal activity and protecting both the mammary gland and nursing infant against various pathogens [29].
Cellular
Macrophages Active phagocytosis of microbes recognised to be “non self” or pathogenic [32].
Lymphocytes and subsets Phagocytosis of microbes recognised to be pathogenic [32].
Polymorphonuclear Leucocytes Phagocytosis of microbes recognised to be pathogenic [32].
Enzymes
Lysozyme  Attack and lysis to bacterial cell walls [32].
Lactoperoxidase  Anti-streptococcal activity [32].
Proteins
Lactoferrin Inhibited Enterotoxigenic Escherichia coli induced hemagglutination of human erythrocytes in vitro [32].
Lactadherin Inhibits the replication of rotaviruses [32].
Erythropoietin Effects on the integrity of infant’s gut epithelia [5].
Mucin Inhibit the binding of pathogenic bacteria and viruses to buccal epithelial cells [30].
Hypothesised to strengthen mucosae against injury caused by specific parasitic infections [30].
Other molecules
Transforming Growth Factor (TGF-β) Mediate anti-inflammatory responses [5].
Interleukin-1 and Interleukin-8 Resistance to certain digestive processes [27]
Nerve Growth Factor, Insulin-like Growth Factor, Tumor Necrosis Factor (TNF-α) and Fibroblast Growth Factor Hypothesised non-specific anti-parasitic protection [31].
Enhances mucosal barriers and decreases incidence of some neonatal diseases such as necrotising enterocolitis [29,31,33].
Table 1: Known and hypothesised protective factors in breastmilk, could these factors be augmented by maternal vaccination?