COMPARISON OF EARLY AND LATE ASTHMATIC RESPONSES BETWEEN PATIENTS WITH ALLERGIC RHINITIS AND MILD ASTHMA

Allergic rhinitic subjects without symptoms of asthma show airway hype rresponsiveness, but to a lesser degree than asthmatics. As airway res ponsiveness is a determinant of the bronchial response to allergen, rh initic subjects should also respond to allergen challenge, but to a le sser extent than asthmatics. However, studies have so far failed to sh ow quantitative differences in allergen responses between patients wit h rhinitis and patients with asthma. We studied 123 allergic subjects classified, on the basis of a scored symptom questionnaire, as follows : pure rhinitics without any symptom of asthma (Group 1, n=39), true a sthmatics with or without rhinitis (Group 2, n=41), and subjects with borderline symptoms of asthma (Group 3, n=43). All subjects underwent both methacholine and allergen inhalation challenges, with pollen chal lenges performed out of season. When the three groups were pooled, the asthma symptom score was directly correlated with the sensitivities b oth to methacholine and allergen, whilst both the sensitivity to aller gen and the severity of late-phase response were correlated with the s ensitivity to methacholine. The percentage of subjects with a positive early-phase asthmatic response to allergen was similar in Groups 1 an d 2, Group 2 had higher sensitivities both to methacholine and to alle rgen than Group 1. A late-phase asthmatic response occurred more frequ ently in Group 2 than in Group 1, and this difference was due to a hig her occurrence of late-phase response in subjects allergic to house du st mite in Group 2. This study confirms that the bronchial response to allergen can be predicted, in rhinitic as well as in asthmatic allerg ic subjects, on the basis of airway responsiveness to methacholine. We conclude that the presence or the absence of asthma symptoms in aller gic subjects may be related to a quantitatively different airway respo nsiveness to allergen.