The twenty lung specimens obtained from patients with ALI included sixteen surgical lung biopsies and four transbronchial lung biopsies considered adequate for histologic review (i.e., containing alveolated lung parenchyma). All control biopsies were taken from uninvolved areas of surgically resected lung tissue removed for treatment of lung cancer. Lung tissue biopsies were fixed in 4% buffered formalin, embedded in paraffin, and serial 4 μm thick sections were cut. Histopathological and immunohistochemical staining of lung tissue sections H&E staining was performed using an automated stain processing unit in the Mayo Clinic Arizona clinical histology unit. Immunohistochemistry was performed using a EPX-mAb as previously described [34] . Evaluations of the slides were performed with either an Olympus BX50 or a Zeiss Axiophot compound microscope.