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Bronchial challenge to house dust can induce immediate bronchoconstriction in allergic asthmatic patients.

The goal of the study was to evaluate whether natural exposure to house dust could elicit immediate bronchoconstriction. Two groups of asthmatic patients were studied: 12 asthmatics allergic to house dust mites and seven nonallergic asthmatics. The baseline FEV1 was similar in the two groups. Each subject was challenged through a nasal mask connected to nebulizer filled with house dust. Patients were randomly assigned to inhale dust with high or low Group I allergenic level. All allergic patients had an FEV1 drop larger than 20% of the baseline value. This drop was maximal at the 30th minute after challenge. FEV1 remained unchanged in nonallergic asthmatics. Allergic patients challenged with high Group I allergenic house dust (8.4 micrograms/g) had a mean FEV1 drop larger (P less than .01) than those challenged with the low Group I allergenic house dust (0.66 micrograms/g). Late asthmatic reactions were found in only two patients who were challenged with the high Group I allergenic house dust. These two patients had immediate FEV1 drops greater than 50% of the baseline value. Occurrence of symptoms during the test and the drop in FEV1 were correlated (r = .3; P less than .05). Natural exposure to house dust can induce immediate bronchial in allergic asthmatics in a dose-dependent manner.