Fig 1: Immunofluorescence for PAPP-A synthesis by inflammatory cells from CRSwNP. (a) Eosinophils; a moderate number of cells are visible in the field. A few cells display co-localization of ECP (red) and PAPP-A (green), appearing as an orange merged signal (indicated by arrow). (b) Mast-cells; a moderate number of cells are present. A few tryptase-positive mast cells (red) show co-localization with PAPP-A (green), as indicated by the arrows pointing to merged orange signal. (c) T-cells; a moderate number of cells are distributed across the field. Few CD3e-positive T-cells (red) show co-localisation with PAPP-A (green), as highlighted by the arrows. (d) B-cells; moderate cells are visible throughout the field. No evident co-localisation between CD20-positive B-cells (red) and PAPP-A (green) is observed. (e) Macrophages; a moderate number of cells are present with CD163-positive staining (red) distributed across the tissue. No co-localisation with PAPP-A (green) is detected. (f) Neutrophils; a moderate number of cells are visible. No evident co-localisation between HNE-positive staining (red) and PAPP-A (green) is observed. The arrows indicate the merged staining corresponding to PAPP-A and the specific biomarkers of inflammatory cells. Scale-bar: 50 µm.