IgE binding structures of the major house dust mite allergen Der p I.

The group I allergens Der p I and Der f I are potent allergens of mites from the genus Dermatophagoides. IgE radioimmune dot blots and immunoabsorption with recombinant peptides have been used to define areas of antigenicity. Four linear binding regions comprising residues 15-33, 60-80, 81-94 and 101-111 were found in the N terminal domain and one, 155-187, in the C-terminal domain, but direct evidence for their discontinuous nature is shown. Firstly, the binding activity of residues 60-80 required either C- or N-terminal flanking sequences to express reactivity and secondly a discontinuous determinant was directly demonstrated by the two non-overlapping peptides 53-99 and 101-154 which significantly cross absorbed specificities to one another. This also indicates considerable homogeneity in the antibodies recognising these peptides. The IgE binding peptides could be located to equivalent residues on the X-ray crystallographic structure of the homologous proteins actinidin and papain. The residues 81-94 and 101-111 which gave strong reactivity were located on a flexible loop connecting the domains and represent areas in which synthetic peptides could be expected to retain activity.