Biospecimen Collection

Nasal brushing is central because it is minimally invasive, inexpensive, efficient, and suitable for repeated sampling. The protocol presents sputum induction and bronchoscopy as more burdensome and less complete in large studies than nasal brushing. Prior work cited by the protocol found high concordance between nasal airway epithelial cells and lower-airway cells for non-ubiquitously expressed genes. Nasal epithelial cells are collected at every asthma study visit and once from healthy controls. Blood samples are collected for DNA, genotyping, RNA sequencing, serum, plasma, and peripheral blood mononuclear cells. Biospecimens are stored and processed in batches to reduce batch effects.