B) Methods: ICs of several food proteins in human exocrine fluids were determined with sandwich ELISAs constructed with anti-individual protein and anti-human IgA antibodies. The IC fraction obtained from human pooled saliva by ammonium sulfate precipitation and gel filtration was administered orally for successive 6 days to 8 weeks old BALB/c mice fed casein-based commercially available mouse diet. At day 8, they were immunized with egg white proteins in Freund’s complete adjuvant and boosted at day 22 with egg white proteins in Freund’s incomplete adjuvant. Blood was drawn from orbital vein and serum ovalbumin and ovomucoid specific IgG1s were measured at day 36. As the control, free ovalbumin corresponding to its amount in the IC fraction was administered.
C) Results: Food proteins were detected as respective ICs in healthy human saliva. IgG1 production to ovalbumin and ovomucoid was significantly suppressed (p<0.05) in the IC administered mice in comparison with the control mice.
D) Conclusions: ICs of food proteins and IgA could be determined in human saliva as well as in breast milk. Evidence indicating their physiological function as the inducers of oral tolerance was proved in mice. ICs of food proteins and IgA in human exocrine fluids are thought to be “Natural Drinkable Vaccine”, functioning in the prevention of food allergy through induction of oral immune tolerance.
1) Biosci. Biotech. Biochem., 65, 1438-1440, 2001
2) Food and Nutr. Sci., 6, 221-233, 2015