목적: Since the COVID-19 pandemic, nasal brushing (NB) has been widely used to investigate the immune system of the upper respiratory mucosa. NB is simple, non-invasive, and time-efficient sampling technique, making it easy to obtain samples even from healthy individuals. However, it is necessary to verify whether NB accurately reflects the phenotype and function of the cellular components in whole nasal mucosal tissue. Therefore, this study aims to compare the cell populations between NB and nasal tissue (NT) samples and identify the differences in immune responses. 방법:Paired NB and NT samples were obtained from the same nasal polyp in patients with chronic rhinosinusitis. Single-cell RNA sequencing (scRNA-seq) analysis of paired NB and NT samples was performed to examine frequencies and phenotypes of immune and stromal cell types in detail. Flow cytometry analysis was performed to validate cell frequencies and phenotypes and the activation-induced marker (AIM) assay was conducted to analyze immune responses against SARS-CoV-2 spike and house dust mite (HDM) antigens. 결과:scRNA-seq analysis revealed that NB samples rarely include endothelial cells, B/plasma cells, and fibroblasts but exhibit a higher frequency of epithelial cells compared to NT samples. A detailed analysis of epithelial cells showed that the frequency of secretory cells was significantly higher in NB than in NT, while the frequency of submucosal gland cells was significantly lower. Additionally, the expression of tissue-resident markers, including CD69, ITGAE, and CXCR6, in T cells was higher in NB compared to NT. Flow cytometry analysis showed that the frequency of CD45+ cells was lower in NB than in NT. Additionally, the frequency of B and CD4+ T cells was significantly lower in NB than in NT, whereas the frequency of NK and CD8+ T cells was significantly higher. Consistent with scRNA-seq analysis results, CD69+CD103+ tissue-resident T cells were enriched in NB compared to NT. When the response to SARS-CoV-2 spike and HDM antigens was assessed using AIM assays, the frequency of AIM+ cells and the proportion of positive AIM responses were significantly lower among both CD4+ and CD8+ T cells in NB compared to NT. 결론:While NB has the advantage of being a non-invasive method for sample collection, differences in cell populations and immune responses exist between NB and NT samples. NB may be useful for analyzing the phenotypes of epithelial cells and tissue-resident T cells in the upper airway mucosa. Our current study provides valuable information for studying the immune system of the upper airway mucosa.