Immunohistochemichal localization of IRAK-3 in lung tissues of A) spontaneous breathing rats, B) rats ventilated at low (6 ml/kg) tidal volume, and C) rats ventilated at high (20 ml/kg) tidal volume. Black and white arrows in A and B point to cytoplasmatic and nuclear staining of epithelial type II cells and interstitial macrophages surrounding the alveolus, respectively. The inflammatory infiltrate with monocytes and lymphocytes and the absence of detectable IRAK-3 in C are due to the effect of high VT ventilation. Results are from at least 8 independent experiments. Tissues are counterstained with hematoxylin. Original magnification ×400.