Figure 2.

Hypothesis regarding the role that local cytokine responses play in the recruitment and activation of B lymphocytes in CRS. (1) Activation of epithelium with Toll-like receptor (TLR) agonist (especially TLR3) leads to BAFF production via an autocrine stimulation pathway that involves IFN-β. (2) BAFF is released by epithelial cells as well as hematopoietic lineage cells in CRSwNP. (3) B cells are stimulated to undergo proliferation, class switch recombination, differentiation, and survival by BAFF and other local factors, leading to production of IgA, IgE, and other immunoglobulin isotypes. (4) The processes of local B cell activation and IgA production as well as IgA transport are regulated by the 12/15 lipoxygenase pathway. See text for details.