Fig. 7: A Model for the role of perivascular mast cells in guiding neutrophils out of the pericyte layer of blood vessels.

Upon acute inflammation, perivascular MCs release the cytokine IL-17A that promotes localised enrichment of intercellular adhesion molecule 1 (ICAM-1) and chemokine CXCL1 on nearby pericytes from post-capillary venules. This response induces a graded expression of those the key molecules within the pericyte layer, allowing for the directed migration of neutrophils in the subendothelial space and subsequent exit from the vessel wall towards the nearest MCs.