Fig. 2.
Fetal T cells differentiate into Tregs upon stimulation with alloantigens. (A) Fetal T cells depleted of CD25+FoxP3+ cells were stimulated for 5 days with unrelated APCs, and FoxP3 expression was measured in proliferating T cells. (B) Kinetic analysis of CD25 and FoxP3 up-regulation by adult and fetal CD4+ T cells after stimulation with alloantigens. (C) Fold difference in cytokine mRNA expression in normal adult (n = 4) and fetal (n = 5) LNs. Genes found to be significantly different are labeled in red (fetal) or blue (adult) (P < 0.05, unpaired Student’s t test). Asterisks denote TNF family members involved in organogenesis. (D) Inhibition of TGFβ signaling by addition of the activin receptor–like kinase inhibitor, SB-431542 (1 uM), which blocks FoxP3 up-regulation by fetal T cells stimulated with unrelated APCs. (E) TGFβ-dependent acquisition of suppressive function after stimulation of fetal T cells with alloantigens. Error bars indicate SD observed in three separate experiments.