Leukocyte infiltration, mediated by chemokines, is a key step in the development of organ dysfunction. Lung and liver neutrophil infiltration following trauma-hemorrhage is associated with upregulation of monocyte chemoattractant protein-1 (MCP-1). Since MCP-1 is not a major attractant for neutrophils, we hypothesized that MCP-1 influences neutrophil infiltration via regulation of keratinocyte-derived chemokine (KC). To study this, male C3H/HeN mice were pretreated with MCP-1 antiserum or control serum and subjected to trauma-hemorrhage or sham operation. Animals were sacrificed four hrs after resuscitation. One group of trauma-hemorrhage mice receiving MCP-1 antiserum was also treated with murine KC during resuscitation. Plasma levels and tissue content of MCP-1 and KC were determined by BD^TM Cytometric Bead Arrays. Immunohistochemistry was performed to determine neutrophil infiltration; organ damage was assessed by edema formation. Treatment with MCP-1 antiserum significantly decreased systemic, lung and liver levels of MCP-1 and KC following trauma-hemorrhage. This decrease in MCP-1 levels was associated with decreased neutrophil infiltration and edema formation in lung and liver following trauma-hemorrhage. Restitution of KC in mice treated with MCP-1 antiserum restored tissue neutrophil infiltration and edema. These results lead us to conclude that increased levels of MCP-1 cause neutrophil accumulation and distant organ damage by regulating KC production during the post-injury inflammatory response.