Figure 2.

Generation of a B cell–specific knockout of inhibitor of differentiation 3 (Id3) reveals that the loss of Id3 in B cells does not result in altered numbers of B-1a B cells or E06 levels. A, Left, Id3 and β-tubulin protein in total splenic B cells from Id3^fl/flApoe^−/−CD19^+/+, Id3^fl/+Apoe^−/−CD19^Cre/+, Id3^fl/flApoe^−/−CD19^Cre/+ and Id3^fl/fl, Apoe^−/−, CD19^Cre/+ mice. Right, Peritoneal lavage cells were sorted from Id3^fl/flApoe^−/−CD19^+/+ (open bar) or Id3^fl/flApoe^−/−CD19^Cre/+ (closed bar) mice for B-1a (CD19⁺B220^lo CD5⁺) cells as in Figure II in the online-only Data Supplement, and Id3 transcript was measured by real-time polymerase chain reaction and normalized to a housekeeping gene, cyclophilin b (CypB). B, Quantification of peritoneal B-2 and B-1a B cell subsets by flow cytometry in Id3^fl/flApoe^−/−CD19^+/+ (n=10) or Id3^fl/flApoe^−/−CD19^cre/+ (n=11) mice at 8 weeks. C, Serum levels of E06 in Id3^fl/flApoe^−/−CD19^+/+ (open circles) or Id3^fl/flApoe^−/−CD19^cre/+ (closed circles) mice were determined by ELISA. Values are the mean relative light units of duplicate determinations.