In LPS-stimulated human neutrophils, engagement of the adenosine A2A receptor selectively prevented the expression and release of TNF-α, MIP-1α/CCL3, MIP-1β/CCL4, MIP-2α/CXCL2, and MIP-3α/CCL20. In mice lacking the A2A receptor, granulocytes that migrated into the air pouch 4 h after LPS injection expressed higher mRNA levels of TNF-α, MIP-1α, and MIP-1β than PMNs from wild-type mice. In mononuclear cells present in the air pouch 72 h after LPS injection, expression of IL-1β, TNF-α, IL-6, and MCP-2/CCL6 was higher in A2AR knockout mice. In addition to highlighting neutrophils as an early and pivotal target for mediating adenosine anti-inflammatory activities, these results identify TNF-α and the MIP chemokine family as gene products whose expression is pivotally affected by activation of A2AR in LPS-activated PMNs. Modulation by A2AR in the production of inflammatory signals by PMNs may thus influence the evolution of an inflammatory response by reducing the activation status of inflammatory cells. ; Shaun R. McColl, Mireille St-Onge, Andree-Anne Dussault, Cynthia Laflamme, Line Bouchard, Jean Boulanger, and Marc Pouliot