Patterns of immunoglobulin E sensitization to chironomids in exposed and unexposed subjects

We present our study of four patients with occupational type I allergy to r ed midge larvae (group 1) who we compared with seven individuals also sensi tized to red midge larvae but who had not apparently been exposed to them ( group 2). All patients showed elevated specific IgE against Chironomus thum mi, and positive skin prick tests (SPT) and provocation tests with red midg e larvae. We carried out SPT with Dermatophagoides pteronyssinus, Acarus si re, shrimp, cockroach and common mosquito (Culex pipiens) and specific seru m IgE was also determined. The red midge larvae wheal size was significantl y larger in group 1 (x = 149.2 mm(2)) than in group 2 (x = 18 mm2). Signifi cant differences between levels of IgE anti-C. thummi were also found in gr oup 1 (x = 52.12 kU/l) and in group 2 (x = 1.5 kU/l). The patients in group 2 had high levels of specific IgE against other allergens (D. pteronyssinu s, shrimp and/or common mosquito) and had positive SPTs with these allergen s, while the patients in group 1 were only sensitized to chironomids. The I gE-immunoblotting profile was quite different in both groups. The patients in group 1 seemed to have IgE against Chi 1 1, the main Chironomus allergen , while the patients in group 2 had IgE against several protein bands in Ch ironomus, mosquito, shrimp and D. pteronyssinus extracts, some of them with equivalent molecular weights. We believe that the patients in group 2 were sensitized to Chironomus as a result of cross-reactivity with other insect or crustacean species.