Assessment of the potential of legume lectins to act as a mucosal adjuvant

Mucosal vaccines can be used to treat systemic inflammatory diseases through the induction of antigen-specific mucosal tolerance. An in vivo mouse model was developed to demonstrate the beneficial adjuvant effect of Phaseolus vulgaris lectin (PHA) using a well-studied T-dependent dietary antigen ovalbumin (OVA). A preliminary experiment was conducted to determine the adjuvant dose. Antigen uptake increased in the circulation after the oral administration of a single feed of 25 mg OVA co-administered with 10 mug or 100 mug PHA-L adjuvant. For the assessment of tolerance induction mice were sensitised with a single feed of 2 mg of OVA and immunised subcutaneously with 100 mug OVA and 10 mug of complete Freud adjuvant 7 d later. Peripheral tolerance was assessed one week later. Our studies with the legume agglutinin PHA clearly demonstrated that orally administered lectin can facilitate oral tolerance induction to an unrelated, but anatomically co-localized marker antigen (OVA).