Loss of endotoxin tolerance in GR^CD11c-cre mice.

<p>(A) Tolerizing dose of LPS-induced loss of CD8⁺ DCs in WT but not GR^CD11c-cre mice. Mice were treated with 0.5 μg/g body weight of LPS for 24 hr and rechallenged with 3 μg/g body weight of LPS for 3 hr before splenic DCs were analyzed by flow cytometry. The experiment was repeated three times, with three mice in each group per experiment. (B) High-dose LPS induced IL-12 production by DCs in GR^CD11c-cre mice despite prior exposure to low-dose LPS. Ten to twelve wk female GR^CD11c-cre mice (<i>n</i> = 4) and control mice (<i>n</i> = 5) were treated with 0.5 μg/g body weight of LPS for 24 hr and rechallenged with 10 μg/g body weight of LPS for 6 hr. Percentage of IL-12⁺ DCs in the spleen of a representative mouse is shown (left panel). Average numbers of total IL-12⁺ DCs were calculated based on the total number of splenocytes in each mouse (right panel). (C) Body temperature of mice rechallenged with 10 μg/g body weight of LPS 24 hr after tolerization. Results were pooled from two independent experiments, <i>n</i> = 8 for WT and <i>n</i> = 5 for GR^CD11c-cre. (D) Serum levels of TNF-α, IL-1β, IFN-α, and IFN-γ from mice in (B) were measured 6 hr after rechallenge. (E) Body temperature of mice rechallenged with 10 μg/g body weight LPS 24 hr after tolerization and 1 hr after injection with 250 μg anti-IL-12 or isotype control. Results were pooled from two independent experiments with one to two mice per condition, respectively, <i>n</i> = 3 per condition. The asterisk indicates the time by which all GR^CD11c-cre mice had died. All WT and the GR^CD11c-cre animals treated with anti-IL-12 survived. The data used to make this figure can be found in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002269#pbio.1002269.s001" target="_blank">S1 Data</a>.