Differential Neutrophil Traffic in Gut and Lung After Scald Injury

Neutrophil recruitment to the lung after thermal injury has been reported by various laboratories. Changes in neutrophil populations in the gut and lung have not been examined simultaneously after burn injury. Mice aged 8 to 10 weeks were anesthetized and subjected to 15% topical scald injury. Animals were sacrificed at 30 minutes and 1, 2, 4, 8, 16, and 32 hours after injury with harvesting of terminal ileum and lung for myeloperoxidase (MPO) assay. Lungs were evaluated after bronchoalveolar lavage and lavage of the vascular bed to remove neutrophils in these compartments. Myeloperoxidase activity was compared between groups of sham-injured and burned animals. Although pulmonary neutrophil recruitment was obvious after scald burn; in the ileum, burned animals showed diminished MPO activity. Histology and bronchoalveolar lavage revealed no evidence of gross organ injury apart from obvious changes in cellular content in the lung. Thermal injury is associated with differential neutrophil movement in the lung and the gut in this model. Pulmonary neutrophil recruitment is confirmed, whereas the gut seems to lose neutrophils as indicated by diminished MPO activity in the initial hours after dorsal scald injury.