Mite allergens: an overview.

Mite allergens from the Pyroglyphidae family are the most frequent and potent sources of perennial asthma and rhinitis. Since 1988 molecular knowledge has considerably increased and structures and functions have been determined for most of them. Of the 22 denominated allergens, Der p 1 and Der p 2 are major allergens recognized by more than 80% of lgE from Dpt allergic patients in Europe. Der p 4, Der p 5 and Der p 7 appeared to be intermediate allergens. The binding of IgE to groups 3, 6, 8, 9, 10 and 20 is constantly low. Most of the allergens can be identified by amino-acid sequences and the tertiary structure of the major allergens has been solved. Most Dpt mite allergens are proteolytic enzymes: Der p 1 for instance is a cysteine protease. Der p 2 has structural homology with MD-2, a co-receptor of the Toll-like receptor (TLR4) whose ligand is LPS. Knowledge of the mite allergens structure has allowed a better interpretation of cross reactions between allergens from the same family or from more distant families. From a practical point of view molecular epidemiology has allowed a better choice of allergen molecules useful for diagnosis. Finally, new concepts of immunotherapy based on genetically engineered hypoallergenic variants of major allergens, used alone or in combination, can be considered.