Structure of IgE epitopes on a new 39-kD allergen molecule from the house dust mite, Dermatophagoides farinae

Two IgE epitope sequences comprising Ser56-Pro-Val-Thr-Lys-Arg-Ala-Ser-Leu-Lys-Ile-Asp-Ser-Lys-Lys70 and Asp104-Val-Glu-Leu-Ser-Leu-Arg-Ser-Ser-Asp-Ile-Ala115 were identified by deletion analysis of the cDNA encoding a new 39-kD protein of mite allergen. A synthetic dodecapeptide corresponding to the latter epitope sequence functioned as a monovalent and mite-specific hapten. Replacement of each of the 12 amino acid residues with Gly, using site-directed mutagenesis, indicated that Arg110 may play a central role in IgE binding. However, the 8 allergic sera tested exhibited a wide variation in their amino acid residues required for reactivity to IgE in allergic sera.