Sections of lungs from young (A, C, E, and G) and aged (B, D, F, andH) mice at 6 and 24 h after receiving a burn injury were stained with anti-Gr-1 (green) and anti-MOMA-2 (red) antibodies. Representative fluorescent images are shown with a differential interference contrast overlay to indicate the alveolar architecture in lungs from animals 6 h after sham injury (A and B), 6 h after burn injury (C and D), 24 h after sham injury (E and F), and 24 h after burn injury (G and H). All images are at 400× original magnification.