Figure 9.

BATF is required for preGC B cell expansion and is up-regulated in Foxo1-deficient preGC B cells. (A, top) Schematic illustration of the experimental protocol. Batf^+/+ ERT2cre B1-8^hi (CD45.1⁺CD45.2⁺) and Batf^f/f ERT2cre B1-8^hi (CD45.1⁻CD45.2⁺) B cells were co-transferred into recipient mice (CD45.1⁺CD45.2⁻), which were immunized with NP-CGG/alum i.p. on day 0. Mice were administered tamoxifen or vehicle p.o. for 3 d and analyzed on day 4. (bottom left) Flow cytometry of NP-specific donor B cells (CD45.2⁺B220⁺NP⁺). (bottom right) Histograms showing the cell number of total donor cells (CD45.2⁺NP⁺B220⁺) and early GC B cells (CD45.2⁺NP⁺B220⁺GL7+CD38⁻) in 10⁶ splenocytes. n = 4 biological replicates. (B) Real-time qPCR analysis of Batf mRNA expression in control and Foxo1-deficient B1-8^hi preGC (donor B220⁺NP⁺CD38⁺GL7⁺) and LZ GC B cells (donor B220⁺NP⁺GL7⁺CD38⁻CD86^hiCXCR4^lo). preGC B cells and LZ GC B cells were prepared from mice as described in Fig. 1 C and Fig. 2 A, respectively. n = 3 biological replicates. Error bars represent SD. Data are representative of three (A) or two independent experiments (B). *, P < 0.05; **, P < 0.01; ***, P < 0.001; paired Student’s t test (A) and unpaired Student’s t test (B).