title: The identification of plant lectins with mucosal adjuvant activity.
abstract: To date, the most potent mucosal vaccine adjuvants to be identified have been bacterial toxins. The present data demonstrate that the type 2 ribosome-inactivating protein (type 2 RIP), mistletoe lectin I (ML-I) is a strong mucosal adjuvant of plant origin. A number of plant lectins were investigated as intranasal (i.n.) coadjuvants for a bystander protein, ovalbumin (OVA). As a positive control, a potent mucosal adjuvant, cholera toxin (CT), was used. Co-administration of ML-I or CT with OVA stimulated high titres of OVA-specific serum immunoglobulin G (IgG) in addition to OVA-specific IgA in mucosal secretions. CT and ML-I were also strongly immunogenic, inducing high titres of specific serum IgG and specific IgA at mucosal sites. None of the other plant lectins investigated significantly boosted the response to co-administered OVA. Immunization with phytohaemagglutinin (PHA) plus OVA elicited a lectin-specific response but did not stimulate an enhanced response to OVA compared with the antigen alone. Intranasal delivery of tomato lectin (LEA) elicited a strong lectin-specific systemic and mucosal antibody response but only weakly potentiated the response to co-delivered OVA. In contrast, administration of wheatgerm agglutinin (WGA) or Ulex europaeus lectin 1 (UEA-I) with OVA stimulated a serum IgG response to OVA while the lectin-specific responses (particularly for WGA) were relatively low. Thus, there was not a direct correlation between immunogenicity and adjuvanticity although the strongest adjuvants (CT, ML-I) were also highly immunogenic.
authors.affiliation: Institute for Immunology, Department of Biology, National University of Ireland, Maynooth, Co. Kildare, Ireland.
authors.forename: E C
authors.initials: EC
authors.lastname: Lavelle
authors.forename: G
authors.initials: G
authors.lastname: Grant
authors.forename: A
authors.initials: A
authors.lastname: Pusztai
authors.forename: U
authors.initials: U
authors.lastname: Pfüller
authors.forename: D T
authors.initials: DT
authors.lastname: O'Hagan
mesh_terms: D000276:Adjuvants, Immunologic; D000818:Animals; D002772:Cholera Toxin / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D018928:Immunity, Mucosal; D007114:Immunization; D007071:Immunoglobulin A, Secretory / Q000096:biosynthesis*; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000097:blood; D037102:Lectins / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010047:Ovalbumin / Q000276:immunology; D028321:Plant Preparations; D010940:Plant Proteins; D054790:Ribosome Inactivating Proteins, Type 2; D014118:Toxins, Biological / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D007071:Immunoglobulin A, Secretory; D007074:Immunoglobulin G; D037102:Lectins; D028321:Plant Preparations; D010940:Plant Proteins; D054790:Ribosome Inactivating Proteins, Type 2; D014118:Toxins, Biological; C488862:mistletoe lectin I; C009674:ribosome inactivating protein, Viscum; D010047:Ovalbumin; D002772:Cholera Toxin