Fig. 6.

Macrophage accumulation in lung tissues. Immunohistochemical assessment of macrophage numbers was performed on tissue sections obtained from pups exposed to prenatal saline or LPS and postnatal room air (open bars) or 85% O₂ (solid bars) for 14 days (top) or 28 days (bottom). [See photomicrographs in supplemental data.] Inflation-fixed lung sections were stained with Mac3 antibodies, and number of macrophages was quantified by digital analyses of the sections. Macrophages were counted in 5 fields for each slide and averaged. Data were analyzed by 2-way ANOVA and modified t-test post hoc (n = 4–5 mice per group and time point). On day 14, there was an effect of prenatal LPS, an effect of postnatal hyperoxia, and an interaction between prenatal LPS and postnatal hyperoxia. On day 28, statistical analyses indicated persistent effects of prenatal LPS and postnatal hyperoxia exposure and an interaction between prenatal LPS and postnatal hyperoxia macrophage numbers. Values are means ± SE. Identical symbols above bars indicate statistical significance between groups: *P ≤ 0.05; §,†,‡P ≤ 0.01.