Isolation and characterization of Tha p 1, a major allergen from the pine processionary caterpillar Thaumetopoea pityocampa

BACKGROUND: Pine processionary caterpillars induce dermatitis by a toxic-irritative mechanism. The existence of true allergic reactions to allergens from these caterpillars has been recently demonstrated by positive immediate skin prick tests and specific IgE determination by immunoblotting using crude larval extracts. The aim of this work was to purify allergens from the crude larval extract in order to characterize IgE-binding proteins from these caterpillars. METHODS: Allergens were separated by ethanol gradient fractionation and reversed phase HPLC. The N-terminal amino acid sequence of a selected allergen was obtained after SDS-PAGE and transfer. The clinical relevance of this allergen was measured using sera from patients allergic to caterpillar. RESULTS: An allergen with a molecular weight close to 15 kDa was purified. It was recognized by 9 out of 11 allergic patients (82%). Its N-terminal amino acid sequence had no homologies to any other protein already described in data bases. For this reason, no information about its biological function could be obtained. CONCLUSIONS: This 15-kDa IgE-binding protein is a major caterpillar allergen and shows no homologies to other insect allergens already described.