The greater stability of the TSDR demethylation status and CD27 expression by naive Treg cells compared with CD25int mTreg cell during expansion showed important differences between these populations. Critically, an enhanced stability of suppressive function after expansion in TAC by CD25int mTreg cells compared with naive Treg cells prompted the measurement of the suppressive cytokine IL-10 and any divergence in its production between Treg cell populations.