Seasonal allergic asthma and non-specific bronchial responsiveness

Summary Bronchial responsiveness to methacoline (PD20 FEV1 mcg) was measured in 64 non smoker asthmatic patients with baseline FEV190% predicted. Patients underwent skin prick tests (SPT) and RAST.Allergic patients had: SPT3+ and RAST-score>II class to the same antigen and correlation with asthmatic symptoms; non allergic patients had negative SPT and RAST. We divided patients in four groups: 1st) allergic seasonal asthmatics before pollen season; 2nd) allergic seasonal asthmatics during pollen season; 3rd) allergic perennial asthmatics; 4th) non-allergic perennial asthmatics.A significant difference in log PD20 was observed between 1st and 2nd group (p<0.0005); between 1st and 3rd group (p<0.0005); between 1st and 4th group (p<0.0005). In allergic seasonal asthmatics before pollen season 10/20 subjects were non-responsive to methacholine (PD201600 mcg), while in 2nd, 3rd and 4th group no subjects were non-responsive.The authors conclude that non-specific bronchial hyperresponsiveness to methacoline is not constant in seasonal allergic asthmatics out of pollen season.