The identification of plant lectins with mucosal adjuvant activity

Immunology. 2001 Jan;102(1):77-86. doi: 10.1046/j.1365-2567.2001.01157.x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic*
  • Animals
  • Cholera Toxin / immunology
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Immunity, Mucosal*
  • Immunization
  • Immunoglobulin A, Secretory / biosynthesis*
  • Immunoglobulin G / biosynthesis
  • Immunoglobulin G / blood
  • Lectins / immunology*
  • Mice
  • Mice, Inbred BALB C
  • Ovalbumin / immunology
  • Plant Preparations*
  • Plant Proteins*
  • Ribosome Inactivating Proteins, Type 2
  • Toxins, Biological / immunology


  • Adjuvants, Immunologic
  • Immunoglobulin A, Secretory
  • Immunoglobulin G
  • Lectins
  • Plant Preparations
  • Plant Proteins
  • Ribosome Inactivating Proteins, Type 2
  • Toxins, Biological
  • mistletoe lectin I
  • ribosome inactivating protein, Viscum
  • Ovalbumin
  • Cholera Toxin