Consistent with neutrophil trafficking into the lungs of mice with ALI/ARDS, chemoattractants known to be produced by macrophages [21] and associated with ALI/ARDS-related injuries [22], such as the chemokines KC (CXCL-1) and MIP-2 (CXCL-2), were found at higher concentrations in sera of mice with ALI/ARDS than in that of mice with HP on both the 3rd and 5th dpi (Fig 2D and 2E). Here, CXCL1 is linked to acute respiratory distress syndrome.