Nasal provocation test induced by LTD4 will be conducted by measuring nasal airway resistance and airway symptoms in a stepwise concentration of LTD4 by nasal spray. Inflammation biomarkers, such as eosinophilic granulocyte in sputum and nasal lavage, fractional exhaled nitric oxide(FeNO), and lung function before and after nasal provocation will be studied to explore the impact of LTD4 nasal provocation test on airway inflammation.
