Contact urticaria to Compositae: Ratibida columnifera, the Prairie Coneflower

• Published in: Journal of allergy and clinical immunology Vol. 113; no. 2; p. S133
• Main Authors: Thornblade, C.E., Whisman, B.A., Hagan, L.L.
• Format: Journal Article
• Language: English
• Published: St. Louis Mosby, Inc 2004; Elsevier Limited
• ISSN: 0091-6749; 1097-6825
• DOI: 10.1016/j.jaci.2003.12.475

Compositae (Asteraceae) family members are known to cause allergic rhinitis in sensitized individuals. Contact dermatitis to Compositae family members has also been described. We report a case of IgE mediated contact urticaria to a common wildflower in the Compositae family, Ratibida columnifera. An atopic patient with a complaint of urticaria within minutes after contact with Ratibida columnifera was evaluated. The exposure occurred while mountain-biking on trails in South Central Texas. The flower heads were reported to strike the patient's legs as he was riding. Samples of the wildflower were collected and identified. The patient and five non-atopic control subjects were skin tested with coneflower extract prepared from the collected flower heads. IgE immunoblotting was performed using the patient's serum and cord serum as a control. The patient had a positive prick skin test to the Ratibida columnifera extract, whereas the five control subjects were negative. The patient's immunoblot revealed IgE binding to 5 bands between 10 kd and 75 kd. The cord serum control immunoblot showed no IgE binding. Contact urticaria caused by Ratibida columnifera, a member of the Compositae family, is reported. Extraction of allergen from the wildflower, skin testing, and immunoblotting suggests a Type I allergic reaction.