Resident memory B cells are enriched in chronic rhinosinusitis with nasal polyps.

Background: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a chronic nasal and sinonasal inflammatory disease. Recently, resident memory B (BRM) cells have been identified in the lungs, although not in the sinonasal mucosa. Objective: Our aim was to characterize memory B-cell phenotypes with regard to patients with CRSwNP and identify BRM cells in both normal sinonosal mucosa and samples from patients with CRSwNP. Methods: CD19 Results: Although BRM cells were found in the normal sinonasal mucosa, their numbers and frequencies tended to be limited. These findings were confirmed on the basis of immunohistochemical analyses indicating an upregulation of CD69/CD45RB in tissue sections from patients with CRSwNP, although not in normal sinonasal mucosa. Accordingly, BRM cells were established to be enriched in the nasal polyps isolated from patients with CRSwNP. Conclusion: Our findings in this study reveal that BRM cells can be detected in normal sinonasal mucosa, although they are significantly enriched in nasal polyps derived from patients with CRSwNP. These findings can contribute to gaining a more comprehensive understanding of the immune reactions associated with CRSwNP and facilitate the identification of potential therapeutic targets, such as anti-B-cell therapy.