Figure 9

Effects of NO ₂ inhalation on antigen-containing dendritic cells in the mediastinal lymph node. Mice were exposed to air or 15 ppm NO₂ for 1 hour followed by oropharyngeal aspiration of 50 μg of ova-Alexa 647. MLN were harvested 2 and 48 hours later, single cell suspensions were generated and stained with antibodies, and cells were analyzed by flow cytometry. CD11c⁺MHCII⁺ cells (DCs) were gated as a percentage of CD45⁺ cells in the MLN (A). DC retention of the antigen ova-Alexa 647 was quantified by the median fluorescence intensity (MFI) of Alexa 647 (B). The histogram represents ova-Alexa 647 retention at 48 hours post exposure (C). NO₂-exposed animals are represented by a thick line while air-exposed animals are represented by a thin line. Grey, filled histograms are naive controls (did not receive ova-Alexa 647) (C). The maturation status of the DC population was assessed by expression of MHCII (D). Data shown are mean ± SEM with 4 animals per group and are representative of experiments performed twice. * denotes p < 0.05 versus air control at the same time point by unpaired Student's t test. ^ denotes p < 0.05 versus 2 hours post NO₂ exposure by unpaired Student's t test.