Figure 5. Mechanisms that maintain immaturity of intestinal CD4 T cells during the homeostatic postnatal period.

(a) Percentage of CD44^hi CD4 T cells in the SI of 11-day-old B-cell-sufficient (μMT^+/− or μMT^+/+) (left panel) and IgA-sufficient (pIgR^+/− or pIgR^+/+)(right panel) neonates fed by B-cell or IgA-sufficient (wt mother) or deficient (μMT^−/− or pIgR^−/− mother) dams. (μMt: n=4 litters from four experiments; pIgR: n=2 litters from two experiments, mean; unpaired Student's t-test, **P<0.01, ***P<0.001). (b) Comparative proliferation assay culturing OVA-loaded BMDCs, eFluor670-labelled OTII cells together with neonatal or adult PP cells for 3 days at the indicated ratio (ratio PP:OTII; n=4 technical replicates, representative of five similar independent experiments, mean±s.d.; one-way ANOVA, Bonferroni's post test, ***P<0.001). (c) Comparative proliferation assay culturing OVA-loaded BMDCs, and eFluor670-labelled OTII T lymphocytes together with FACS-sorted subgroups of neonatal PP cells for 3 days at the ratio of 4:1 (PP:OTII: B and T cells) or 2:1 (PP:OTII: stroma and rest). (n=3–4 technical replicates, representative of four similar independent experiments, mean±s.d.; one-way ANOVA, Bonferroni 's post test, ***P<0.001). (d) Comparative proliferation assay culturing OVA-loaded BMDCs, eFluor670-labelled OTII T lymphocytes together with FACS sorted neonatal regulatory T cells (T_Reg, from Foxp3 reporter mice) for 3 days at the ratio of 4:1 (ratio PP:OTII). (n=2 replicates from two experiments with T_Regs pooled from 20 and 8 neonates per experiment, respectively, mean±s.d.; one-way ANOVA, Bonferroni 's post test, ***P<0.001, NS, not significant). (e) Percentage of CD44^hi cells among CD4 T lymphocytes (using non-transgenic littermate controls as a reference gate) in the SI of 11-day-old DEREG mice and non-transgenic littermate controls all treated with DT on days 1/2/5/6 (n=5 litters from five experiments, mean; unpaired Student's t-test, **P<0.01.