PMN-mediated interference with the chemokine network promotes monocyte efflux. (I) PMN granule proteins promote de novo synthesis of monocyte-attracting chemokines such as MCP-1 and MIP-1α by neighboring endothelial cells and macrophages. (II) PMN-derived proteases cleave chemokine proforms either enhancing or attenuating their monocyte attracting capacities. (III) Complexes of soluble IL-6 and IL-6R shed from PMNs activate endothelial cells via gp130 to synthesize MCP-1 and VCAM-1. (IV) In the presence of appropriate stimuli (eg, fMLP, TNF, LPS), PMNs produce and secrete monocyte-attracting chemokines themselves.