Background We have previously reported that asthma differs from rhinitis with or without bronchial hyperresponsiveness in the perception and degree of lower airway inflammation.
Objective The aim of the present study was to investigate whether sputum levels of inflammatory markers could further distinguish these patient groups.
Methods Patients with seasonal allergic rhinitis with or without asthma or bronchial hyperresponsiveness to methacholine were investigated. Induced sputum was performed during as well as off season, and analysed for cysteinyl-leukotrienes, hyaluronan, eosinophilic cationic protein (ECP) and other inflammatory markers.
Results Asthmatic patients differentiated from those with rhinitis with or without bronchial hyperresponsiveness in levels of cysteinyl-leukotrienes [geometric mean: 3.3 (lower 95%–upper 95% confidence interval (CI) of geometric mean: 1.9–5.1) vs. 1.4 (0.9–2.2) and 0.7 (0.3–1.6) pg/μg total protein] and hyaluronan [0.30 (0.22–0.43) vs. 0.15 (0.10–0.20) and 0.20 (0.12–0.35) ng/μg total protein] in sputum. The levels of cysteinyl-leukotrienes decreased in sputum from the asthmatic patients, while the levels of hyaluronan remained elevated off-season. Furthermore, elevated levels of ECP were noticed among both the asthmatic and rhinitis patients with hyperresponsiveness compared with controls [0.022 (0.014–0.033) and 0.015 (0.011–0.021) compared with 0.010 (0.007–0.014) ng/μg total protein]. The level of ECP remained elevated off season.
Conclusion Cysteinyl-leukotrienes are possibly more related to mast cell-mediated inflammation and remodelling, also indicated by increased levels of hyaluronan during and off season. This inflammation may be partly different from the eosinophil-driven inflammation.