Helios expression in thymocytes depends on cell stimulation and not origin.

<p>(A) Helios- Foxp3+ subsets were gated within murine thymic cells, and CD4 and CD8 distribution was analyzed. More than half (bottom) of Foxp3+ Helios- cells and 24% (top) of Foxp3^hi Helios- cells in the thymus were immature CD4+ CD8+ DP thymocytes. (B) Murine thymic cells were incubated for 3 days with IL-2 only (non-stimulated, left column) or were stimulated with CD3/CD28 mAbs and IL-2 (stimulated, right column). Ki-67 expression (top) and Helios expression (middle) in non-stimulated cells decreased markedly; and Helios expression in thymic Tregs (CD4+ SP Foxp3+ cells) decreased from 91% to 57% (bottom).