2.2 | Isolation and identification of primary human nasal epithelial cells (HNECs)
We collected nasal mucosal specimens from patients who met the diagnostic criteria described previously. We isolated HNECs from these specimens using the collagenase digestion method (collagenase IV, Sigma Aldrich, USA). We subsequently performed cytokeratin-19 (CK-19) immunohistochemical and immunofluorescence analyses.31, 32