Chronic upper airway inflammation is characterized by an extrafollicular B cell response and elevated antibody production in humans (HUM1P.260)

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Abstract Chronic rhinosinusitis (CRS) is an upper airway disease that affects 30 million Americans and a subgroup of CRS patients also has nasal polyps (CRSwNP). In CRSwNP patients, inflamed sinus tissues can be removed as part of treatment, which provides a unique model system to investigate mechanisms of human mucosal inflammation. We have previously reported local elevations in NP of B cells, antibodies (Ab), and expression of Epstein-Barr virus-Induced protein 2 (EBI2), a marker of extrafollicular plasma cells (PC). To characterize the mechanisms mediating these responses, we assessed B cells from fresh tissue (d0) or after 4 days of culture (d4) from NP, uncinate tissue (UT) or tonsils from CRS and control subjects by flow cytometry. We measured Ab production by multiplex array and assessed formation of B cell follicles by immunohistochemistry. We assessed the Ab repertoire by DNA deep sequencing and by analysis of Ab genes from single cells. We found that NP uniquely supported the accumulation of PC (p<0.01) and Ab production (p<0.05) in vitro. Plasmablasts (PB) and PC were Ki67+, and EBI2 expression was highest on PB. We found no evidence for increased B cell follicles in NP compared to control UT (n>10/group). Ab from NP had fewer CDR3 mutations than Ab from UT (p<0.05), but more mutations than Ab from peripheral blood (p<0.05). These data suggest that there is a strong extrafollicular B cell response in NP that may drive Ab production during chronic airway inflammation.