The effect of immunotherapy on bronchial hyperresponsiveness in asthmatic children.

Bronchial hyperresponsiveness (BHR) to methacholine were evaluated in 47 asthmatic children before and after allergen-specific immunotherapy (IT) by using the forced oscillation method. Eighty-seven percent (13/16) of BHR-negative patients had good clinical response after 1-year immunotherapy while there were only 45% (14/31) in the BHR-positive asthmatic children (p < 0.02). In the BHR-positive group, the relationship between clinical response and the change of nonspecific bronchial sensitivity was further analyzed. In those of good clinical response (IT responder), the tolerance dose of methacholine was significantly increased from 0.78 +/- 0.71 to 4.11 +/- 4.65 mg/ml (p < 0.05), and bronchial sensitivity increased from 1.14 +/- 1.42 U to 7.55 +/- 9.55 U (p < 0.02). In those with no clinical improvement (IT non-responder), there were no significant changes in either methacholine tolerance dose or bronchial sensitivity. With respect to other parameters, such as Grs, PD35, and SGrs, the differences between before and after immunotherapy were similar in both the IT responders and IT non-responders. These results suggest that asthmatic children with different bronchial sensitivity had different responses to immunotherapy and the clinical improvement after immunotherapy is significantly related to the improvement of bronchial hyperresponsiveness.