Fig. 4. T_FH cell generation and IgE elevation in response to food Ags are developmentally regulated.

(A to D) GF mice (6.5 weeks old) were treated with anti-ICOSL antibody for 2 weeks to deplete T_FH cells. Mice were analyzed to examine the level of T_FH cells at days 2 and 28 after cessation of anti-ICOSL antibody treatment (n = 3). (A) Schematic view of experimental design and time plan. (B) Representative FACS plots of PD-1 and CXCR5 gated on CD4⁺ TCRβ⁺ Foxp3⁻ CD44^hi cells. (C) Number of PD-1^hi CXCR5⁺ T_FH cells. (D) Serum IgE levels of control mice and mice with T_FH depletion at days 0 and 28 were measured by ELISA. (E to G) Young and adult AF mice (4 and 8 weeks of age, respectively) were switched to NCD for 4 weeks (n = 4). Representative FACS plots showing PD-1^hi CXCR5⁺ T_FH cells gated on CD4⁺ TCRβ⁺ Foxp3⁻ CD44^hi cells (E) and number of PD-1^hi CXCR5⁺ T_FH cells (F) from MLN and PP of indicated mice. (G) Serum IgE levels in indicated mice by ELISA. Each symbol represents an individual mouse. All data are representative of two independent experiments. Statistical differences were determined by one-way (C, F, and G) or two-way (D) ANOVA with Tukey’s multiple comparisons test. **P < 0.01, ***P < 0.001. Error bars represent SEM.