Figure 8: Continuous antigen supply generates resident CD4⁺ T cells in PPs.

(a) Experimental setup for (b,c), wherein 2 × 10⁷ CD45.1⁺ spleen/LNs cells from OT-II mice were adoptively transferred into WT recipients. One day later, some of the mice were immunized with 50 mg OVA+10 μg CT p.o. (OVA+CT) or not (CTRL). Then some of the immunized mice received OVA in drinking water for 1 week (OVA+CT DW). (b) CD45.1⁺ transferred cells in PPs 7 days after immunization (representative of three independent experiments). (c) Frequency of CD45.1⁺Vβ5⁺CD62L^lo among all CD4⁺ T cells in mLN (left) and in PPs (right) (n=4 mice per group in three independent experiments, not significant (NS); *P<0.05; **P<0.01; ***P<0.001; one-way analysis of variance (ANOVA), Tukey’s post test). (d) Experimental setup for e–g, wherein 14 days after immunization, FITC was injected into the PPs and mice were analysed 7 days later (day 21). Mice received OVA in the drinking water for 1 week (days 0–7, OVA+CT DW 1W) or for 3 weeks (d0–21, OVA+CT DW 3W), or not (OVA+CT). (e) CD45.1⁺ transferred cells in PP_inj (left) and PP_ctrl (right) in a mouse from OVA+CT DW 3W group (representative of two independent experiments). (f) Frequency of CD45.1⁺Vβ5⁺CD62L^lo among all CD4⁺ cells in PP_inj (n=3–5 mice per group in two independent experiments not significant (NS); ***P<0.001; one-way ANOVA, Tukey’s post test). (g) Frequency of FITC⁺ among CD4⁺CD45.1⁺Vβ5⁺CD62L^lo cells in PP_inj (Not determined (ND), not significant (NS), unpaired Student’s t-test). i.v., intravenous.