Selective loss of λ⁺ B cells during BM and peripheral B-cell maturation. BM (A) and spleen (B) cells from an 8-week-old C57BL/6 mouse were stained with FL-anti-IgM, BI-anti-CD23 (revealed with SA-PECy5.5), APC-anti-AA4, PE-Cy7-anti-B220, and either PE-anti-κ or PE-anti-λ (λ1 + λ2) before collection of 200 000 events on an LSR2 flow cytometer. Fr E indicates sIgM⁺ AA4⁺ BM B cells. Data are representative of 5 separate experiments.