(A) Histograms showing expression of MBC markers CD80, PD-L2, CD73, and FAS on CD11b+CD11c+ ABCs (black line), compared with CD11b−CD11c− naïve B cells (gray), from representative 19-month-old female WT mouse. (B) Left panel: FACS plots showing gating of CD11b+CD11c+ ABCs and CD11b−CD11c− naïve B cells from representative WAS chimera mouse. (Middle, left panels) Surface CD80/PD-L2 and CD80/CD73 expression on naïve B cells (middle) and ABCs (left). Number indicates % within CD80+PD-L2+ and CD80+CD73+ gates.