Food allergy to honey: pollen or bee products? Characterization of allergenic proteins in honey by means of immunoblotting.

OBJECTIVE: To characterize the allergenic components of honey, 23 patients allergic to honey were investigated. All displayed allergic symptoms after ingestion of honey or honey-containing products, ranging from itching in the oral mucosa to severe systemic symptoms to anaphylactic shock. METHODS AND
RESULTS: Immunoblot analyses of the patients' sera revealed IgE binding to proteins at a molecular mass of 54 kd, 60 kd, 72 kd, or to a 30 kd/33 kd double band, or to both in sunflower honey extracts. The three bands corresponding to higher molecular mass proteins could also be detected in the three other kinds of honey (locust tree, European chestnut and forest honey) that were tested and represented bee products because IgE binding to these proteins was inhibited by extracts of honeybee heads and extracts of isolated bee venom sacs. The 30 kd/33 kd bands could be identified as sunflower honey-specific. When testing sera from patients allergic to bee venom with honey extracts, in seven of 10 cases IgE binding to bee-specific components could be observed.
CONCLUSION: Both proteins derived from secretions of pharyngeal and salivary glands of honeybee heads and pollen proteins contained in the honey cause allergic reactions to honey.