Figure 1.

IFNα and IFNγ synergize with TLR7 and TLR9 to promote the differentiation of single-κ and dual-κ MRL/lpr B cells into GC B cells. (A) Schematic of the in vivo treatment of 6 week old MRL/lpr mice with the TLR9 ligand CpG. (B) Flow cytometric analysis and gating strategy of splenic B cells from MRL/lpr mice injected with either PBS or CpG. The cells were serially gated to measure the frequency of PNA^highCD38^low GC B cells within the single-κ and dual-κ B cell populations. (C, D) Frequencies of dual-κ B cells and PNA^highCD38^low GC B cells within the single-κ and dual-κ cell populations, in MRL/lpr mice treated with either PBS or CpG. N=4, analyzed in two independent experiments. Data is shown as mean+SD. Statistical analysis was performed with a one-tailed unpaired t-test. (E) Flow cytometric analysis of B cells enriched from the spleen of MRL/lpr mice (8-15 weeks of age) and cultured for 60 hours in media alone or with R848, R848+IFNα, or R848+IFNγ. The cells were serially gated to measure BCL6⁺GL7^high GC B cells within the single-κ and dual-κ B cell populations. (F) Frequencies of BCL6⁺GL7^high GC B cells within the single-κ and dual-κ B cell populations of MRL/lpr B cells cultured as described in (E). N=6, analyzed over one experiment (data from a similar experiment are in Supplementary Figures S1 D–F). Data are shown as mean+SD. Statistical analysis was performed with a one-tailed unpaired t-test. *p ≤ 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001; ns, not significant.