Class I endochitinase containing a hevein domain is the causative allergen in latex-associated avocado allergy.

Abstract

BACKGROUND:

In the medical literature immunoglobulin (Ig)E-mediated sensitization to avocado is rarely reported. On the other hand, more than 50% of subjects having IgE-mediated natural rubber latex allergy are sensitized to avocado fruit as demonstrated by skin-prick testing and/or specific IgE measurements and about 10-20% report hypersensitivity reactions after ingesting avocado.

OBJECTIVE:

The underlying pathomechanism of latex-associated avocado allergy is still unknown. The conserved hevein domain of the major latex allergen prohevein (Hev b 6.01) is a ubiquitous chitin-binding protein structure that can be found in several plant proteins and may be responsible for the observed cross-reactivity between latex and avocado fruit.

METHODS:

Chitin-binding avocado proteins (CBAPs) were isolated by affinity-chromatography and their IgE-binding characteristics were studied by immunoblotting using the sera from 15 avocado-sensitized latex patients. Inhibition experiments using isolated hevein and CBAPs as inhibitor solutions were performed to study the immunological cross-reactivity between both protein species and to assess the role of the CBAPs as mediators in latex-associated avocado allergy.

RESULTS:

In 80% of avocado-sensitized subjects (n = 15), IgE antibodies directed against a 31-kDa allergen were detected by immunoblotting. This IgE-binding protein was identified by protein sequencing to be a class I endochitinase containing a hevein domain at the N-terminus. Purified native and digested (using simulated gastric fluid) endochitinase were able to completely block all avocado-specific IgE antibodies in six out of seven avocado patients.

CONCLUSIONS:

Sensitization to endochitinase class I containing a hevein domain is the main underlying pathomechanism in latex-mediated avocado allergy.

• Authors: A Posch, C H Wheeler, Z Chen, A Flagge, M J Dunn, F Papenfuss, M Raulf-Heimsoth, X Baur
• Journal: Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology (Clin Exp Allergy) Vol. 29 Issue 5 Pg. 667-72 (May 1999) ISSN: 0954-7894 [Print] England
• PMID: 10231327 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Allergens
• Antigens, Plant
• Antimicrobial Cationic Peptides
• Hev b 6.01 protein, Hevea brasiliensis
• Latex
• Lectins
• Plant Lectins
• Plant Proteins
• Protein Precursors
• hevein
• Chitin
• Immunoglobulin E
• Chitinases

Topics

• Allergens (immunology)
• Antigens, Plant
• Antimicrobial Cationic Peptides
• Chitin (metabolism)
• Chitinases (chemistry, immunology, metabolism)
• Cross Reactions
• Food Hypersensitivity (immunology)
• Health Personnel
• Humans
• Immunoblotting
• Immunoglobulin E (blood)
• Latex (adverse effects)
• Latex Hypersensitivity
• Lauraceae (adverse effects, enzymology)
• Lectins (chemistry, immunology)
• Plant Lectins
• Plant Proteins (chemistry, immunology)
• Protein Precursors (immunology)
• Skin Tests