Animals

All animal protocols were approved by the Animal Care and Use Committee at the University of Virginia. Apolipoprotein E deficient (ApoE^−/−) mice were purchased from Jackson Laboratory and maintained in our animal facility (University of Virginia). Id3^fl/fl mice were a generous gift from Dr. Yuan Zhang (Duke University). CD19^Cre/+ mice were provided by Timothy Bender (University of Virginia). Id3^fl/fl mice were bred to the ApoE^−/− line and then with CD19^Cre/+ mice to develop B cell specific Id3 knockouts and littermate controls (ApoE^−/−Id3^WT: ApoE^−/−.CD19^+/+.Id3^fl/fl and ApoE^−/−Id3^BKO: ApoE^−/−.CD19^Cre/+.Id3^fl/fl) as previously described (Perry et al., 2013). All purchased mice were on C57BL/6J background and those bred were backcrossed to C57BL/6J mice for 10 generations. All mice were given water ad libitum and standard chow diet (Tekland, 7012). Mice were euthanized with CO₂ inhalation. Young (8–10 weeks) male mice were used for all experiments except for atherosclerosis studies. For atherosclerosis studies, ApoE^−/− mice were maintained on WD (42% fat, Tekland, 88137) for 12 weeks.