Figure 3. Blimp1 Deficiency Impairs T_FR Suppressive Activity and Alters Gene Expression by T_FR Cells.

(A and B) Splenic T_FR, T_FH, GC B, and expression of IL-17A in Treg cells from the indicated mouse strains (6–8 weeks old) 10 days post-immunization with NP-OVA in CFA (A). Frequencies of Treg, T_FR, T_FH, GC B cells, and IL-17A⁺ Treg cells, FoxP3 MFI, and total and high-affinity anti-NP IgG titers (B).

(C–G) (C) Schematic presentation of experimental protocol. CD45.2⁺ WT, KO, and CD45.1⁺ mice were immunized with NP-OVA in alum. Seven days later, sorted T_FR (CD4⁺CD3⁺PD-1⁺CXCR5⁺YFP⁺) along with CD45.1⁺ T_FH (CD4⁺CD3⁺PD-1⁺CXCR5⁺GITR⁻) and GL7⁻ B cells (B220⁺GL7⁻) were transferred into Rag2^−/− hosts followed by immunization with NP-OVA in alum before analysis (day 7).

(D) Fluorescence-activated cell sorting (FACS) profile (upper) and numbers (bottom) of T_FR (CD45.2⁺CD4⁺CD3⁺PD-1⁺CXCR5⁺FoxP3⁺) and ex-T_FR (CD45.2⁺CD4⁺CD3⁺CXCR5⁻) cells.

(E) Intracellular IL-17A and IFNγ expression by donor T_FR cells.

(F) Histogram (upper) and MFI (bottom) of the indicated markers by donor CD45.2⁺ WT T_FR cells (red) and CD45.2⁺ KO T_FR cells (blue).

(G) Flow cytometry of donor CD45.1⁺ T_FH (CD45.2⁻CD4⁺CD3⁺PD-1⁺CXCR5⁺) and GC B cells (CD19⁺GL7⁺) 7 days post-immunization.

(H) Tcra^−/− mice were transferred with sorted T_FR (WT versus KO) along with CD45.1⁺ T_FH cells, followed by immunization with NP-OVA in CFA. Serum ANA, anti-NP23 IgG, IgG1, and IgE levels were analyzed 10 days post-immunization.

In (A) and (B), the data are pooled from two independent experiments (n = 5/group). In (C)–(H), the data are representative of three independent experiments (D and F, n = 4/group; H, n = 3–4/group). N.S., no significance, *p < 0.05, **p < 0.01, ***p < 0.001, and ****p < 0.0001 (unpaired two-tailed Student’s t test). Error bars indicate means ± SEMs.

See also Figure S2.