Allergic conversion of protective mucosal immunity against nasal bacteria in patients with chronic rhinosinusitis with nasal polyposis.

BACKGROUND: Chronic rhinosinusitis with nasal polyposis (CRSwNP) is characterized by eosinophilic inflammation and polyposis at the nose and paranasal sinus and a high concentration of IgE in nasal polyps (NPs). The causative antigen and pathogenesis of CRSwNP remain unknown. OBJECTIVE: We aimed to identify reactive allergens of IgE antibodies produced locally in NPs of patients with CRSwNP. We also attempted to unravel the differentiation pathway of IgE-producing B cells in NPs. METHODS: IgE reactivity of patients with CRSwNP was investigated by characterizing single cell-derived mAbs. T-cell response against identified allergens was investigated in vitro. NP-infiltrating lymphocytes were characterized by using flow cytometry. Immunoglobulins expressed in NPs were analyzed by using high-throughput DNA sequencing for immunoglobulin. RESULTS: About 20% of isolated IgE antibodies derived from NP-residing plasmablasts specifically recognized surface determinants of nasal bacteria, such as Staphylococcus aureus, Streptococcus pyogenes, and Haemophilus influenzae. A TH2 response against S pyogenes was observed in patients with CRSwNP. Flow cytometric analysis revealed sizable germinal center B-like cell and plasmablast subsets expressing IgE on the cell surface in NPs. High-throughput DNA sequencing immunoglobulin analysis highlighted the clonal connectivity of IgE with IgG and IgA1. The Iε-Cα1 circle transcript was detected in NPs. CONCLUSIONS: In patients with CRSwNP, nasal bacteria-reactive B cells differentiate into IgE-producing B cells through IgG/IgA1-IgE class switching, suggesting that allergic conversion of the mucosal response against nasal bacteria underlies disease pathogenesis.