Polyclonal B cell activation and perturbed B cell development in double mutant mice. (A) Representative histograms of lymph node CD19+ B cells stained with CD69 to detect activation status. Shaded histogram represents wild type for comparison. Animals were assessed at age 6 months. (B) Plasma cell marker CD138 expression among splenocytes (%) at age 3 months. (C) Representative cytometry plots of CD19+ splenocytes stained with CD23 and AA4.1 to identify transitional (T1, T2) and follicular mature (FO) B cell subsets. (D) Quantification of subsets identified in (C). (E) Representative cytometry plots of CD19+ splenocytes stained with IgM and IgD to identify transitional (T1, T2), marginal zone (MZ) and FO mature B cell subsets (FM). (F) Quantification of subsets identified in (E). Animals in figures (C)– (F) were 2 months of age at the time of analysis. In figures (B), (D), and (E) values are the mean of three biological replicates +/− SEM. All of the data presented are representative of at least 3 independent experiments at varying time points.