Examination of nasal secretions
Cytological examination of nasal secretions was performed when children had no signs of an acute respiratory infection. Nasal secretions were sampled by swabbing the bilateral inferior turbinates with cotton swabs. The samples were spread onto a slide glass, air-dried, fixed and stained with Hansel solution (Eosinostein®; Torii Pharmaceutical, Tokyo, Japan). The specimens were examined by light microscopy for eosinophils, neutrophils and bacteria by a single well-trained laboratory technician. Nasal eosinophilia was defined as the presence of more than a few eosinophils in the whole field. The percentage of eosinophils compared with neutrophils was also determined, and >10% was defined as significant nasal eosinophilia.17