Regulatory T (Treg) cells play an important role in the establishment and maintenance of immune tolerance. Most Treg cells express CD25 molecule, which has a high affinity with IL-2. After activation of CD25, it signals by inducing the activation of transcription factor STAT5. IL-2 plays a central role in many aspects of Treg cell biology.   In addition to TCR signaling, IL-2 – STAT5 is also required to induce Foxp3…