B6.FOXP3-DTR mice were injected with 20,000 SFFU i.v. and left untreated or injected with 0.5 μg DT i.p. at 0, 3, and 6 dpi. Spleens were harvested at 2 wpi and total splenocytes (A, B) or CD19+CD4- B cells (C, D, E) were analyzed by flow cytometry. (B) Absolute numbers of CD19+ cells per spleen. (C) Representative histograms of CD86 expression on B cells; Mean MFI of Naïve: 221, FV: 304.8, FV + DT: 506.5, P < .001. (D) %Ki-67+CD86+ B cells in the spleen. (E) Number of Ki-67+ CD86+ B cells/spleen. Each dot in (B, C, D, E) represents an individual mouse pooled from experiments with 2–6 mice per group. Lines indicate the mean of each group. *P < .05, **P < .01, ***P < .001, ****P < .0001 as determined by ordinary one-way ANOVA with Tukey post-test for multiple comparisons.