Figure 1.

SAP inhibits neutrophil recruitment. (A) In response to chemoattractants, such as CXCL8, neutrophils begin to migrate into the tissue in a process that involves neutrophil rolling, arrest, and extravasation. All of these steps are mediated by adhesion receptors on the endothelial cells and on neutrophils. (B) In the presence of high levels of SAP, neutrophil recruitment to the tissue is reduced, as SAP‐induced IL‐10 inhibits the secretion of CXCL8. SAP also reduces neutrophil adhesion by preventing L‐selectin binding to adhesion receptors on endothelial cells. SAP may further affect neutrophil adhesion by regulating adhesion receptors on neutrophils by inside‐out signaling via FcγRs. In addition, SAP reduces neutrophil migration by inhibiting neutrophil spreading and elastase activity.