ABSTRACT
Mucosal inflammation of the airways is a feature of respiratory infections, allergic rhinitis and asthma. However, there are problems with conventional noninvasive methods of sampling the airways given that blood, breath and sputum samples have individual limitations when used to quantify levels of inflammatory mediators. Despite these caveats, the humble blood eosinophil count and sputum eosinophil numbers remain useful to define eosinophilic phenotypes of asthma in conjunction with more invasive bronchoscopic sampling methods. In this section, we also consider the use of airway mucosal sampling devices and, in particular, synthetic absorptive matrix strips to absorb mucosal lining fluid (MLF) and measure biomarkers of inflammation. Cytokines in serial nasosorption samples from patients with allergic rhinitis given topical nasal allergen challenge have been studied, and nasal and bronchial mucosal responses documented in asthmatics after rhinovirus experimental infection. Subject to rigorous validation in a range of clinical situations, absorption of airway MLF could allow facilitate the diagnosis, stratification and monitoring of a variety of airway diseases.
