Human nasal brush samples are collected using a minimally invasive brushing technique from the nasal cavity, typically the inferior nasal turbinate. These samples yield human nasal epithelial (HNE) cells, which are valuable for studying infectious or inflammatory conditions affecting both upper and lower airways. Nasal brushings are particularly useful for diagnosing primary ciliary dyskinesia (PCD) and for research into other airway diseases like allergic rhinitis, asthma, and cystic fibrosis. The technique provides a high yield of viable epithelial cells suitable for cell culture, differentiation studies, and molecular analysis, including gene expression and biomarker identification.