Different airway responsiveness profiles in atopic asthma, nonatopic asthma, and Sjogren's syndrome

Background: Different mechanisms may underlie bronchial hyperresponsiveness (BHR) in different diseases. The aim of this study was to investigate the bronchial responsiveness profile produced by three different challenge test s, methacholine, a direct simulus, and two indirect stimuli, adenosine 5'-m onophosphate (AMP) and cold air, in subjects with asthma and patients with Sjogren's syndrome. Methods: The study population comprised 40 adult patients with asthma, 18 s ubjects with Sjogren's syndrome, and 20 controls. Blood samples were collec ted before each challenge for measurements of serum eosinophil peroxidase ( S-EPO) and eosinophil cationic protein (S-ECP). The investigated subjects r ecorded peak expiratory how and kept a symptom diary. Results: Atopic subjects with asthma were significantly more hyperresponsiv e to AMP than nonatopic subjects with asthma (P = 0.01) and subjects with S jogren's syndrome (P = 0.02). No difference was seen between atopic and non atopic subjects with asthma in the case of challenges with methacholine or cold air. In atopic subjects with asthma, a significant correlation was fou nd between challenges with methacholine and AMP (r = 0.91, P = 0.0001) and methacholine and cold air (r = 0.83, P = 0.004), but, in nonatopic subjects with asthma, no significant correlation was seen between methacholine and AMP or cold air challenges. In atopic subjects with asthma, the dose-respon se slope for AMP was correlated to S-EPO (r = - 0.56; P = 0.01) and S-ECP ( r = - 0.51, P = 0.02), while no correlation between BHR and inflammation ma rkers was found in the two other patient groups. Conclusions: The results of this study suggest that patients with asthma an d subjects with Sjogren's syndrome display different bronchial responsivene ss profiles for different challenge agents. Atopic subjects with asthma are more hyperresponsive to AMP than nonatopic subjects and patients with Sjog ren's syndrome. More than one challenge may be required to detect different aspects of bronchial responsiveness.