Modulation of ovomucoid-specific oral tolerance in mice fed plant extracts containing lectins.

We investigated the effect of feeding extracts of four different legumes (red kidney bean (Phaseolus vulgaris), peanut (Arachis hypogaea), soyabean (Glycine max) and pea (Pisum sativum) on the specific immune response against a food protein. Mice were fed ovomucoid and the specific immune response was evaluated. Ovomucoid fed alone resulted in oral tolerance induction measured as both a reduced ovomucoid-specific spleen cell proliferation and antibody response. Feeding kidney-bean extract prevented induction of oral tolerance to ovomucoid measured as spleen cell proliferation in vitro. Pure kidney-bean lectin also prevented oral tolerance induction, suggesting that lectin in the kidney-bean extract caused inhibition of oral tolerance. Parenteral administration (intravenous and intraperitoneal) of pure kidney-bean lectin had no significant influence on oral tolerance induction. Soyabean extract also influenced the immune response against ovomucoid; however, this was not as pronounced as for kidney bean and was only significant (P<0.001) for the antibody response. No effect was observed when pea extract was fed and peanut extract had a non-significant effect on induction of oral tolerance and on the general immune response. Plasma antibodies against kidney-bean lectin, but not against the three other legume lectins, were detected. Our current findings show that other dietary components can influence the specific immune response against food proteins. Various dietary components may thus contribute to the onset of adverse immunological responses.