<i>In vitro</i> polarization induces Foxp3 expression in memory BDC12-4.1 T cells but does not endow <i>in vivo</i> regulatory functions.

<p>CD4⁺CD25⁺ cells from splenocytes of BDC12-4.1 mice polarized into Treg cells (A) <i>in vitro</i> in the presence of a-CD3 (left panel) or InsB:9-23 peptide (right panel). Expanded T cells were gated on CD4⁺CD25⁺ cells (not shown) and expression of CD127 and Foxp3 were determined. (B). 1×10⁶ Tregs polarized with anti-CD3 (left panel) or InsB:9-23 peptide (right panel) were adoptively transferred into prediabetic 8-wk old NOD mice and diabetes development was monitored. Unmanipulated NOD mice monitored on a regular basis in our animal colony served as negative controls with cumulative diabetes incidence of ∼90% by 27 wks of age. Representative results from one of three independent experiments are shown.