Figure 3

Comparison of the level of inflammation of lung tissue among anti-PLY IgG-, control IgG-, and PBS-treated mice infected withS. pneumoniaeD39 serotype 2. Histological appearance of representative lungs from mice infected intranasally with S. pneumoniae serotype 2 and treated with anti-PLY IgG (A), and control IgG (B). Numerous leukocytes can be seen in the peribronchial and perivascular areas, and considerable vascular distension and hemorrhage take place during the progression of pneumococcal colonization. Lungs of mice treated with anti-PLY IgG reveal alveoli, bronchioles, and vessels structurally normal, with no signs of acute inflammation and lower leukocyte infiltration. Blood vessel (v), alveolar space (a), bronchiole (b). Scale bars 50 μm. (C) Numbers of infiltrating cells were counted in random areas of lung tissue sections H&E-stained. Results are means ± SD of 3 mice and are representative of three independent experiments. *, P < 0.05 for a comparison of anti-PLY IgG- treated mice with PBS-treated mice, and +,P < 0.05 for a comparison of anti-PLY IgG with control IgG-treated mice, as determined by two-way ANOVA followed by the Bonferroni test.