Two other cell types have been shown to be critical for neutrophil extravasation: first, resident perivascular macrophages from dermal venules are the main source of neutrophil chemoattractants and secrete the chemokines CXCL1, CXCL2, CCL2, CCL3, and CCL4 in an experimental model of bacterial infection of the skin [14]; second, vessel-associated mast cells secrete the chemoattractants CXCL1 and CXCL2 to induce neutrophil extravasation in a model of intraperitoneal lipopolysaccharide (LPS) stimulation [4]. Here, CXCL1 is linked to bacterial infectious disease.