Fig. 2

Tfh and Tregs are both required in the PP for gut IgA responses. a Prior to adoptive transfer (AT) of splenic DO11.10 TCR-Tg CD4 T cells into nu/nu BALB/c mice we sorted them based on CD25 and GITR-expression. Whole TCR-Tg CD4 T cells or highly enriched CD25⁺ or CD25⁻ TCR-Tg CD4 T cells were injected i.v separately or re-mixed together. b Mice were orally immunized with 10 mg of OVA three times with 10 days apart and on day 26 the gut LP anti-OVA IgA or the splenic (SP) IgG SFC responses were determined by ELISPOT. SFC values were analysed in duplicates and are given as means ± SEM/10⁷ mononuclear cells of 16–30 mice in each group. Serum anti-OVA IgG levels were determined by ELISA and given as mean log₁₀-titers ± SEM of 30 mice in each group. c The distribution of CD4 T-cell subsets in PPs after AT of TCR-Tg CD4 T cells into nu/nu BALB/c mice followed by oral immunizations. The Tfh and Treg populations in the PPs were analysed by FACS using antibodies for CD4, KJ126 (OVA-specific), CXCR5, PD-1, Foxp3, and CTLA4. Values are given as mean ± SEM frequencies of OVA-specific Tregs and Tfh TCR-Tg KJ126⁺CD4 T cells and TCR-Tg KJ126^- CD4 T cells. The data are from 1 representative experiment out of 5 independent experiments giving similar results (a, c) or pooled from three to five independent experiments (b). Statistical significance was calculated using two way ANOVA with Tukey’s multiple comparison test. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, ns = not significant