Asthma and rhinitis induced by exposure to raw green beans and chards

Background: Although the vast majority of IgE-mediated allergic reactions t o foods occurs through ingestion, a few cases of unexpected allergic reacti ons to foods may occur through the exposure to airborne food allergen parti cles. Methods: Case reports, Skin prick tests and serum-specific IgE (CAP-FEIA) w ere used to identify specific IgE antibodies. Bronchial provocation tests w ere performed to determine the clinical relevance of inhaled exposure to ra w and cooked green beans and raw chards. After demonstrating specific react ivity to them, SDS-PAGE and immunoblotting of raw and cooked green beans we re carried out to identify relevant antigens. Results: Three women developed bronchial asthma and rhinitis after exposure to raw green brans, and one of them also when exposed to raw chards. All w omen tolerated ingestion of green beans. Patients reported multiple episode s while handling these vegetables for cooking activities. Allergy to green beans and chards was demonstrated by skin testing and serum-specific IgE. B ronchial challenge test with these allergens showed positive responses to r aw, but not cooked, green beans and chards. Oral food challenges with green beans (raw and cooked) and chards were negative in all patients. In order to further characterize the allergenic components of these extracts, SDS-PA GE and electroblotting studies were also performed. Immunoblots of raw and cooked green beans extract showed two IgE-binding bands with apparent molec ular weights of 41.1 and 70.6 kD. Interestingly, a 47-kD IgE-binding protei n was detected only in raw green bean extracts. Conclusions: We report three patients who developed asthma and rhinitis cau sed by exposure to raw, but not to cooked, green beans and chards in a non- occupational environment. Only minor differences of IgE reactivity between nitrocellulose-blotted raw and boiled green bean extract were found.