It is assumed that the reason resulting in such change is either t cell maturation of the down regulation of t cell antigen receptors.

They found it was a simple matter of Numbers: by wearing many hats, or antigen receptors, regulatory t cells can keep their eyes on a lot of different non-regulatory cells.

By pulling receptors away from their surface membrane during signaling, t cells can prevent themselves from being lethally overstimulated by too much antigen.