CCL2 and acute respiratory distress syndrome: 26 In humans, CCL2 and CCL7 have been shown to differentially induce the chemotaxis of macrophages, with CCL7 being the only chemokine to induce the migration of M1 and M2 macrophages.27 More recently, it has been demonstrated that CCL2 and CCL7 can also function as chemoattractants for mouse28, 29 and human neutrophils.30 We now show, for the first time, that CCL2 and CCL7 contribute to the neutrophil chemotactic activity of ARDS BAL fluid and that they synergise with CXCL8 to promote neutrophil chemotaxis.