Rice pollen allergy in Taiwan.

A panel of tests including intracutaneous skin testing (ST), radioallergosorbent test (RAST), immunoblotting and allergen-induced lymphoproliferation was done to study rice pollen allergy in asthmatic children and to characterize the allergens. Of the 312 asthmatic patients skin tested, 29 (9.3%) had positive reactions (wheal greater than or equal to 6 mm) to rice pollen extract at a concentration of 10(-5) g/mL and the remaining 283 (90.7%) were negative. While eight (34.8%) of the 23 ST-positive patients were also RAST-positive, RAST was negative in all 34 ST-negative patients and 20 normals. Immunoblotting revealed three major allergens, with molecular weights of 16 kD, 26 kD, and 32 kD, respectively. Interestingly, RAST-positive patients showed IgE responses to most allergens but only a few of them had IgG antibodies, while normal controls had stronger IgG responses to the same allergens, particularly to 32 kD, but none had IgE antibody. The preliminary results of rice pollen protein induced-lymphoproliferation were not informative; thus, rice pollen proteins do elicit a specific response in asthmatic children and normals, but its pathogenic role in bronchial asthma needs further study.