ALLERGENS FROM HOUSE-DUST MITES OF THE GENUS DERMATOPHAGOIDES - NATURE, ANTIGENIC AND STRUCTURAL CHARACTERIZATION, AND MEDICAL PREPARATIONS

Microscopic mites of the genus Dermatophagoides are the major source o f house dust allergens. Four homologous classes of main allergens have been isolated from extracts prepared from the mites D. pteronyssinus and D. farinae. The main mite allergens are generally believed to be p roteins of gastrointestinal origin. Group I mite allergens Der pI and Der fI are thermolabile glycoproteins with molecular weight 25 kD. Com parison of primary structures revealed 30% homology between group I mi te allergens and cathepsins B and H, papain, and actinidin. The allerg ens are proteolytic enzymes (cysteine proteinases). Study of allergeni c composition revealed three common and two species-specific epitopes on Der pi and Der fI. The amino acid sequences of major allergenic det erminants of Der pI were established. Group II mite allergens Der pII and Der fII are single-chain thermally stable proteins with molecular weights of 10-14 kD. Group II allergens are believed to be analogous t o trypsin. Der pIII and Der fIII showed 50% homology in amino acid seq uences with serine proteinases found in vertebrates and invertebrates. Mite amylase (56-60 kD) is a member of the fourth group of main mite allergens. There is considerable homology between group IV allergens a nd mammalian alpha-amylase. All mite allergens induce production of sp ecific IgE antibodies in humans. The use of purified allergens improve s the quality of diagnosis and treatment of mite allergoses. Modified forms of mite allergens (allergoids, carrier-adsorbed allergens, and l iposome-bound preparations) are now successfully used in specific immu notherapy.