IRF7 signaling is dispensable for foreign antigen–specific GC, PC, and Ab responses in autoimmune-prone mice. 16- to 17-wk-old age- and sex-matched FcγRIIB^−/− (black circles) and FcγRIIB^−/−IRF7^−/− mice (blue circles) mice were immunized with NP-KLH in CFA as described in Materials and methods. The splenic GC, PC, and antibody responses were analyzed on 14 days after immunization. (A and B) Frequencies of (A) CD19⁺B220⁺ total and (B) CD19⁺ B220⁺NP⁺ B cells. (C) Frequency of GL-7⁺CD95⁺ GC B cells of total CD19⁺ B220⁺ B cells. (D) Frequency of NP⁺ cells gated on CD19⁺B220⁺GL-7⁺CD95⁺ B cells. (E) Representative flow plot of total PCs gated on IgD⁻CD138⁺TACI⁺ cells. (F) Gating strategy for different subsets of PCs. (G) Percentages of subsets of PCs (total IgD⁻CD138⁺TACI⁺ PCs, IgD⁻CD138⁺TACI⁺B220^intCD19⁺ plasmablasts, IgD⁻CD138⁺TACI⁺B220⁻CD19⁺ immature PCs, and IgD⁻CD138⁺TACI⁺B220⁻CD19⁻ mature/resting PCs). (H) Representative flow and dot plots of NP⁺ PCs gated on IgD⁻CD138⁺TACI⁺ cells. (I and J) Frequencies of (I) CD44⁺CD62L⁻ splenic effector and (J) CD44⁺CD62L⁻CXCR5⁺PD-1⁺ Tfh of total CD4⁺ T cells. (K and L) (K) High-affinity (NP4) and (L) low-affinity (NP28) anti-NP and total serum IgG and IgG1 titers. Each symbol represents an individual mouse (n = 5 mice per group), and data are presented as means ± SEM. Data in each panel represent two experiments. P values were calculated via an unpaired Student’s t test (A–J) or two-way ANOVA with Dunn–Sidak correction (K and L) (NS, not significant, P > 0.05; *, P < 0.05; **, P < 0.01).