Utility of nasopharyngeal aspirate over other upper airway sampling approaches for cellular immunology during respiratory viral infection

Early immune responses to respiratory viruses in the upper airways, including recruitment of innate immune cells like monocytes and dendritic cells (DCs), dictate disease development. Still, unlike soluble biomarkers, comparative evaluations of upper respiratory sampling methods for immune cell analysis are limited. We longitudinally collected matched nasopharyngeal aspirates (NPA), nostril swabs, nasal curettes, and blood from patients with influenza-like illness and controls. Among the methods tested, NPA yielded the highest numbers of viable immune cells, including monocytes and DCs, while causing similar sampling discomfort and blood contamination, making it superior for longitudinal collection of immune cells from the upper airways.