IgE-mediated inhalant allergy in inhabitants of a building infested by the rice weevil (Sitophilus oryzae).

The rice weevil (Sitophilus oryzae) is known as a stored product pest. Occupants living in a factory used previously as a granary and known to be contaminated by the rice weevil developed rhinitis and asthma. To study the role of the potential insect allergens, extracts were prepared from whole body and a grain dust of the rice and grain weevil (Sitophilus granarius). The extracts were coupled to cyanogen bromide-activated paper disks. Skin prick tests (SPT) were performed using common inhalant allergens as well as the insect allergen preparations. In cases of a positive SPT, specific serum IgE to the insect products was measured. Histamine release studies with peripheral leukocytes (HR) and studies using immunoblot techniques were performed. Fifteen of 39 subjects living in the infested rooms demonstrated positive SPT to the extracts of insect origin. Histamine equivalent wheal size induced by the whole body extract of the rice weevil required 3-160 micrograms protein/mL. Five of 15 subjects (with positive SPTs) had elevated specific IgE-levels to the insect material. RAST-inhibition studies indicated cross allergenicity between rice and grain weevils, and also between the frass of both beetles. Five of 15 subjects were positive in the HR assay (Ag30, allergen concentration for 30% HR for the whole body extract: range, 10(-3) to 400 micrograms protein/mL, maximum release: 26% to 89%). IgE binding was detected after SDS-PAGE by immunoblot techniques at different locations: 35-38, 54, 67, 70, and > 94 kD.(ABSTRACT TRUNCATED AT 250 WORDS)