Résumé
Background. Pine processionary larvae produce urticating hairs (setae) that serve for protection against predators. Setae induce cutaneous reactions in animals and humans. The presence of toxic or allergic mechanisms is a matter of debate. Objectives. To detect the presence of allergens in setae and to characterize them. Materials and methods. Setae extracts were characterized by gel staining and immunoblot, with sera from patients with immediate reactions and positive prick test reactions, as well as a rabbit antiserum raised against setae. Setae proteins were fractionated by high-performance liquid chromatography. The most relevant allergen was analysed by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS), and its sequence was deduced from an expressed sequence tag bank. Results. Setae contained at least seven different allergens. The most intense detection corresponded to a protein of MW ∼14 000 that was similar to thaumetopoein, a previously described protein with mast cell-degranulating properties. MALDI-MS-based de novo sequencing provided a partial amino acid sequence different from that of the previously described allergen Tha p 1, and it was named Tha p 2. This allergen was detected in 61% of patients, and it is therefore a new major caterpillar allergen. Conclusions. Penetration of the setae from the pine processionary caterpillar delivers their allergenic content in addition to causing mechanical or toxic injury