Mucosal immunogenicity of plant lectins in mice

The mucosal immunogenicity of a number of plant lectins with different suga r specificities was investigated in mice. Following intranasal (i.n.) or or al administration, the systemic and mucosal antibody responses elicited wer e compared with those induced by a potent mucosal immunogen (cholera toxin; CT) and a poorly immunogenic protein (ovalbumin; OVA), after three oral or i.n. doses of CT, high levels of specific serum antibodies were measured a nd specific IEA was detected in the serum, saliva, vaginal wash, nasal wash and gut wash of mice. Immunization with OVA elicited low titres of serum I gG but specific IgA was not detected in mucosal secretions. Both oral and i .n. delivery of all five plant lectins investigated [Viscum album (mistleto e lectin 1; ML-1), Lycospersicum esculentum (tomato lectin; LEA), Phaseolus vulgaris (PHA), Triticum vulgaris (wheat germ agglutinin (WGA), Ulex europ aeus I (UEA-1)] stimulated the production of specific serum IgG and IgA ant ibody after three i.n. or oral doses. Immunization with ML-1 induced high t itres of serum IgG and IgA in addition to specific IgA in mucosal secretion s. The response to orally delivered ML-1 was comparable to that induced by CT, although a 10-fold higher dose was administered. Immunization with LEA also induced high titres of serum IgG, particularly after i.n, delivery. Lo w specific IgA titres were also detected to LEA in mucosal secretions. Resp onses to PHA, WGA and UEA-1 were measured at a relatively low level in the serum, and little or no specific mucosal IgA was detected.