The major allergen of the house dust mite, Dermatophagoides pteronyssinus, is synthesized and secreted into its alimentary canal.

The natural production of Der pl, the major faecal allergen from the house dust mite (Dermatophagoides pteronyssinus), was investigated. Mite cultures grown on radiolabelled substrate were examined at intervals over a period of 21 days and incorporation of radiolabel into the mite proteins measured over the time course. Mite proteins were extracted, purified by chromatofocussing and characterized by immunodiffusion, SDS-PAGE, electroblotting and autoradiography. The faecal allergen, Der pl, did not incorporate a significant level of label until the 14th day (p less than 0.05). The results suggest that Der pl is a protein synthesized and excreted by the house dust mite.