A DNA-based fibrous mesh is present in the lungs of mice with TRALI. (A-D) Representative photographs obtained by transmission electron microscopy of the lung epithelial surface of control mice (A), mice with TRALI (B,D), and mice that were injected with LPS (0.5 mg/kg) and received DNase 1 before anti–H-2K^d mAb injection (C). The fibrous material found in TRALI lungs is absent after DNase 1 treatment. Scale bar represents 1 μm. The insets show low magnification views of the lung surface revealing alveolar sacs (a) and ducts (d); inset scale bars represent 2 μm. The pictures are representative of 3 independent experiments.