Fig 1: ABCB7 is required for peripheral B cell proliferation and class switching.(A) Flow cytometry analysis of IgG1, IgG2a, IgG2b, IgG3, and IgA expression on enriched B220+ CD19+ B cells from wild-type (WT) and CD23-cre ABCB7 conditional knockout (cKO) mice after 4 days in culture conditions that induce class switching to the indicated isotypes. Pseudocolor dot plots are representative of five independent experiments (total of five mice/group). (B) Quantification of the proportion (top) and number (bottom) of cells from (A) that class switched to the indicated antibody isotypes. The reported cell number was derived from flow cytometry live CD19+ cells during analysis. (C) Flow cytometry analysis of carboxyfluorescein diacetate succinimidyl diester (CFSE) dilution in cells from (A). Offset histograms are representative of five independent experiments (total of five mice/group). (D) FlowJo proliferation modeling tool was used to quantify the proliferation index (left) and percentage of undivided cells (right) in cells from (C). (E) Intracellular flow cytometric analysis of Ki-67 expression in proliferating B220+ CD19+ cells after 4 days in culture conditions that induce class switching. Contour plots are representative of three independent experiments (total of three mice/group). Quantification of the percentage of undivided, Ki-67- cells is shown on the graph on the right. (B, D, E) Error bars represent SEM, and p-values are indicated above the data. Statistics were obtained by using an unpaired Student’s t-test.