Fig 1.

Structure of the sinus epithelium, submucosal mixed seromucinous glands, and stroma and summary of proteins and peptides produced by sinus mucosal cells of potential relevance to innate or adaptive immune responses. Seromucinous glands are stained positively for CXCL1 (GRO-α). Adapted from references 13 and 71 to 83. *The NGAL protein was observed in the epithelium, infiltrating inflammatory cells, and submucosal gland of NPs but was rarely detected in normal inferior turbinate tissue.⁸⁴ MBL-associated serine protease (MASP) 1 and 2 and MBL are soluble proteins that can arise in sinus secretions from plasma.