Allergy to castor bean. I. Its relationship to sensitization to common inhalant allergens (atopy).

The IgE response to castor bean (Ricinus communis) was studied in 96 castor bean-allergic patients from Marseilles, France. All had positive skin tests to castor bean. The IgE response to grass, cat, dust mite, olive, and Parietaria was also measured, and a positive RAST to one or more of these allergens was taken to indicate atopic status. Castor bean-specific IgE antibodies, measured by RAST, were found in 87 (91%) of the castor bean-allergic patients, in two of 13 atopic Marseilles residents living close to the castor bean mills, in three of 42 allergic subjects who had no known contact with castor bean, and in none of a control group of 111 Marseilles blood donors. Very high levels of castor bean-specific IgE (maximum class 4 readings on the Phadebas RAST score) were found in 54 (56%) of the castor bean-allergic patients, but the level of IgE antibody to castor bean was not significantly different in atopic and nonatopic subjects. The frequency of a positive serological test (RAST) for atopy in castor bean-allergic subjects (32%) was very similar to that found in the local population (36%). These data indicate that castor bean is an extremely potent sensitizer for both atopic and nonatopic individuals. The magnitude of the specific IgE antibody response is not related to the atopic status of the patient and may be a function of the physiochemical characteristics of the allergen itself.