Figure 3.
IRF-4,8-/- pre-B cells have an increased proliferation index and express higher levels of the pre-BCR. (A,B) Cell cycle status of IRF-4,8-/- pre-B cells. Bone marrow cells after enriching for sIgM—B-lineage cells were stained with anti-CD19 and anti-CD43 antibodies. After fixation and permeabilization, the cells were incubated with either 7-AAD or anti-Ki-67 antibody. FACS analysis was performed by gating on CD19+ CD43- cells. Ki-67 staining was assessed using an isotype-matched antibody as control (broken line). (C) Expression of pre-BCR on IRF-4,8-/- pre-B cells. (Top) Freshly isolated bone marrow cells were analyzed by four-color FACS using anti-CD19, CD43, IgM, and pre-BCR antibodies. The FACS profiles were obtained by gating on CD19+, CD43- and IgM-, and cells. (Bottom) The same FACS analysis was performed using pre-B cells that were expanded in culture using IL-7. For each panel, the pre-BCR quadrant was set using an isotype control.