Secretion of vascular endothelial growth factor by human neutrophils

Vascular endothelial growth factor (VEGF) is produced by a variety of cells and plays a pivotal role in inflammation by mediating vascular permeability and angiogenesis. The aim of this study was to establish whether neutrophils may act as a local source of VEGF. Human neutrophils were isolated from citrated venous blood by sequential sedimentation and density centrifugation and VEGF release evaluated after exposure to ionomyrin (0.1-10μg/ml), phorbol dibutyrate (0.1-10μg/ml) or opsonised zymosan. Controls included cells treated with medium alone or dimethylsulphoxide (DMSO). VEGF was assayed by ELISA using antibodies against recombinant human VEGF (R&D Systems) and an immunoperoxidase technique. Ionomycin, phorbol dibutyrate and zymosan activated neutrophils secreted extracellular VFGF in a stimulant, time and dose dependent manner whereas less than 10% of the total available VEGF was secreted by control cells. In separate experiments, these results were confirmed by both Western blotting and immunocytochemistry. Activated neutrophils are, therefore, a potential source of VEGF in inflamed tissue which suggests that they may have a strategic role in the regulation of angiogenesis in acute and chronic inflammation.