Hypersensitivity to chironomids (non-biting midges): localization of the antigenic determinants within certain polypeptide sequences of hemoglobins (erythrocruorins) of Chironomus thummi thummi (Diptera)

Abstract

Ninety-nine individuals who were in contact with larvae of chironomids were investigated. Forty-three developed respiratory, conjunctival, or cutaneous hypersensitivity reactions upon exposure to airborne constituents of these insects. By means of RAST, RAST inhibition, and skin tests, type I sensitization to hemoglobins of chironomids was identified in 33 subjects of the symptomatic group. In one of these cases additional proof for high-grade sensitization was obtained by bronchial provocation with as low as 0.2 μg of one of the isolated hemoglobins. RAST and skin-test investigations with fragments obtained by chemical and enzymatic cleavage of two of the homologous hemoglobins led to localization of the antigenic determinants within the peptide sequences 1-31, 32-90, 91-101, and 109-131 of hemoglobin CTT IV and within the sequence 64-98 of hemoglobin CTT VI of the species Chironomus thummi thummi. Our results show that hemoglobins of chironomids are potent allergens in man. Therefore chironomids must be considered in relation to environmental and occupational sensitization contributing to respiratory diseases. © 1982.