Resolution of BM and splenic B-cell subsets. (A) BM cells and splenocytes from an 8-week-old C57BL/6 mouse were harvested and stained with FL-anti-IgM, PE-anti-CD23, APC-anti-AA4, and APC-Cy5.5-anti-B220 before collection of 200 000 events on an LSR2 flow cytometer. (B) The identical BM and spleen cells shown in panel A were also stained with PE-Cy5.5-anti-CD21/35, APC-Cy7-anti-CD62L, and BI-anti-IgD^b (revealed with SA-PETR). (C) BM and spleen cells from an 8-month-old NG-BAC mouse or an age-matched control were stained with PE-anti-CD23, PE-Cy5.5-anti-B220, APC-anti-AA4, and BI-anti-IgM (revealed with SA-PETR) and RAG2/GFP expression assessed by collecting 200 000 events on an LSR2 flow cytometer. These data are representative of 2 or more separate experiments.