Neutropenic mice have more DNA-containing debris following acid injury of the lung. (A) Lungs from injured areas of WT and G-CSF^−/− lungs were fixed 24 hours after unilateral acid-induced lung injury and stained with hematoxylin-and-eosin sections. Scale bar, 100 μm. The extent of debris is apparent. (B) BAL fluid sampled 24 hours after acid-induced lung injury from neutropenic (G-CSF^−/−) mice and WT mice were compared using mass spectroscopy after depleting albumin and IgG. We appreciated a marked increase in nuclear-associated proteins in the neutropenic mice relative to WT mice. (C) Measurements of BAL nucleic acid concentration at baseline (0 hours), 12 hours, 24 hours, and 48 hours after inducing lung injury show a persistent increase in BAL DNA concentration with a peak occurring 24 hours after injury. (D) Agarose gel electrophoresis of BAL-derived DNA from WT and G-CSF^−/− mice 24 hours after injury. (E) Quantification of the distribution of DNA sizes in BAL in the 2 genotypes. (F) Sytox staining of lung through the intratracheal route before fixation. Little Sytox staining is detected in uninjured lungs. Twenty-four hours after injury, however, Sytox staining appears more intense in G-CSF^−/− mouse lungs than WT. Scale bar, 250 μm. Each point on the graphs represents 1 animal. The error bars represent the standard error of mean. *P < .05; **P < .01; ***P < .001.