Dust mite allergens and asthma: a worldwide problem. International Workshop report.

After the discovery of house dust mites in 1964 their association with asthma has been reported from many different parts of the world including the developing countries. Two sets of major allergens from mites of the genus Dermatophagoides are now well recognized. The Group I allergens are glycoproteins of relative molecular mass (M(r)) 25 000, which show both structural homology and cross-reactivity. The allergen Der p I has been cloned and sequenced confirming the M(r) and establishing its nature as a protease. The Group II allergens (M(r) 15 000) show even closer homology and cross-reactivity. Specific immunoassays for Group I and Group II allergens, using monospecific antisera and monoclonal antibodies, have been standardized and are suitable for measuring allergen levels in different parts of the world.Measures for reducing the levels of mite allergens in houses include the covering of mattresses, hot washing of bedding, and removal of carpets from bedrooms as well as humidity control, vacuum cleaning, and the use of acaricides in the rest of the house. There is already evidence that these procedures can cause a major improvement in the symptoms of asthma. While provisional standards for both sensitization to mites and also mite allergen exposure can now be recommended, there is an urgent need for controlled studies using protocols demonstrated to reduce mite allergen levels by at least tenfold and for further international collaboration.