Induction of oral tolerance, in mice, to gum arabic.

As part of a programme of research on the immunological properties of the exudate gums, the capacity of gum arabic to induce immunologic hyporesponsiveness when fed (oral tolerance) has been examined. Inbred mice were fed saline or gum arabic; 1 week later all were systemically immunized with the antigen emulsified in complete Freund's adjuvant. Mice which had been fed the antigen had significant suppression of the humoral (P less than 0.01) and cell mediated (P less than 0.01) immune responses to the antigen. These results demonstrate that although gum arabic is a complex, proteinaceous polysaccharide antigen, it is tolerogenic when an animal encounters it by the natural route, via the gut.