ABSENCE OF CONTINUOUS EPITOPES IN THE HOUSE-DUST MITE MAJOR ALLERGENSDER-P-I FROM DERMATOPHAGOIDES-PTERONYSSINUS AND DER-F-I FROM DERMATOPHAGOIDES-FARINAE

Background The house dust mite has been shown to be an important sourc e of domestic allergens associated with immediate hypersensitivities. The Group I mite allergens Der p I from Dermatophagoides pteronyssinus and Der f I from D. farinae display extensive amino acid sequence hom ology and have similarities with cysteine protease enzymes. Objective The availability of the complete amino acid sequences for these allerg ens allowed us to search for the allergic determinants within these mo lecules. The aim of the present investigation was to identify any cont inuous IgE-binding epitopes within these amino acid sequences. We also sought to test the validity of previously reported Der p I peptide ep itope sequences. Methods In order to identity any continuous IgE epito pes, the amino acid sequences of Der p I and Der f I were synthesized as decapeptides overlapping in sequence and coupled to plastic pins. T he specific IgE-binding capacity of these peptides was assayed using a n enzyme-linked biotin-streptavidin procedure and sera from patients k nown to be sensitive to these allergens. Previously reported Der p I p eptide epitopes were synthesized as free peptides and tested for their ability to inhibit specific IgE binding to allergen extract discs. Re sults None of the pin-coupled Der p I or Der f I peptides was found by the continuous epitope mapping procedure to bind significantly to spe cific IgE in the sera of hypersensitive patients. The previously repor ted Der p I peptide epitopes did not inhibit specific IgE binding to m ite extract discs. Conclusion The specific IgE binding epitopes of the house dust mite allergens Der p I and Der f I are discontinuous in na ture.