Relationship between Dermatophagoides mite density and specific immune response in asthmatic patients.

Dermatophagoides mites were abundant in the beds of asthmatic patients of Calcutta, India, comprising more than 60% of the total mites isolated in the present study. The patients' bed dust harbored significantly more dense (P < .02) mite populations as compared with bed dust samples of control subjects. The patients' sera contained significantly higher (P << .001) IgE concentrations than the sera of the controls and the sera of 92% patients were found to have elevated IgE levels of more than 300 U/mL. Eighty-five and 82% of patients responded positively to Dermatophagoides mite allergen by radioallergosorbent test (RAST) and skin prick test respectively, highlighting the importance of these mites in producing house dust allergy in Calcutta and its surrounding areas. The results indicate that with a tenfold increase in mite density in the patients' bed dust, the group mean serum IgE level increased considerably (P < .05). The increase in the total serum IgE and in the frequency of positive RASTs and prick tests to Dermatophagoides for allergic asthmatic patients correlated quite well with the increase in the specific mite density in their beds.