Anaphylaxis to camomile: clinical features and allergen cross-reactivity

Background Medicinal remedies of plant origin became very popular in recent years, and allergic reactions to these are on the rise, accordingly. Camom ile has been reported as a potential trigger of severe anaphylaxis. The all ergens responsible for camomile allergy have not been characterized as yet. Objective The present study aims at reviewing the clinical symptomatology o f immediate-type reactions in a series of patients sensitized to camomile a nd at characterizing the responsible allergens. Methods Fourteen patients with a history of allergy either to camomile or t o spices or weeds, and a positive skin prick test/RAST to camomile were inv estigated for related allergic reactions to food, pollen and others. IgE-bi nding patterns were determined by immunoblotting, inhibition tests and degl ycosylation experiments. Results Ten of 14 patients had a clinical history of immediate-type reactio ns to camomile, in some cases life threatening. Eleven subjects were also s ensitized to mugwort in prick or RAST, eight to birch tree pollen. Using a polyclonal rabbit anti-Bet v 1 antibody, a homologue of the major birch pol len allergen Bet v 1 was detected in two camomile blots. In four cases a gr oup of higher molecular weight allergens (23-50 kDa) showed IgE-binding to camomile. All allergens proved heat stable. Binding was inhibited in variab le degrees by extracts from celery roots, anize seeds and pollen from mugwo rt, birch and timothy grass. Deglycosylation experiments proved the presenc e of carbohydrate determinants in camomile which were not responsible for I gE-binding, though. Profilins (Bet v 2) were not detected in our camomile e xtracts. Conclusion Incidence and risk of type I allergy to camomile may be underest imated. Concurrent sensitization to mugwort and birch pollen is not infrequ ent. Bet v 1 and noncarbohydrate higher molecular weight proteins were foun d to be eliciting allergens and are responsible for cross-reactivity with o ther foods and pollen.