House-dust mite asthma. Results of challenge tests on five criteria with Dermatophagoides pteronyssinus.

Twenty-eight patients with asthma and house-dust allergy were investigated by five different challenge tests with mite extract (Dermatophagoides pteronyssinus). These tests were performed on the skin, bronchi, nasal mucosa, and leucocytes, and on normal human lung tissue passively sensitized by the patients' serum. The results were compared with each other and with the clinical state of the patients.Of 21 patients on whom all five tests were carried out, positive reactions to every test were found in 14 (67%). Asthmatic attacks were readily induced by inhalation of the mite extract and occurred in 18 (86%). Nasal reactions were provoked in 18 (86%) and were not followed by asthmatic symptoms. A leucocyte test was positive in 19 (90%) and the serum test was positive in all (100%). Delayed asthmatic responses to bronchial challenge were seen in six patients, but there was no evidence that these were mediated by precipitins. Quantitatively there was no fixed pattern between the degrees of sensitivity of the different tissues in the same patient. The amount of mite antigen capable of causing an asthmatic reaction was extremely small-less than 1 mug. of mite material in several patients.In view of the prevalence of D. pteronyssinus in this country and its high allergenic potency, it is considered that this mite is an important factor in allergic asthma.