What are the markers or surface molecules used to identify regulatory T-cells?

CD4, CD25, CD127 and FoxP3 are the most common markers used to identify regulatory T-cells, also known as Treg cells. 

• CD4: CD4 is a glycoprotein expressed on the surface of T cells, including regulatory T cells (Tregs). CD4 cells play a pivotal role in recognizing and activating T cell antigens, contributing to Treg-mediated immune regulation.
• CD25: CD25 is a marker associated with the high-affinity interleukin-2 receptor expressed by Tregs. CD25 markers are widely used to identify and characterize Treg cells in vitro and in vivo. This is because Treg cells express high levels of CD25 on their surface, contributing to their suppressive and immunomodulatory properties. 
• CD127: CD127, also known as the interleukin-7 receptor alpha chain, is a robust surface marker for identifying and characterizing natural Treg cells. Its decreased expression is a distinguishing feature of Tregs. Monitoring CD127 expression helps to isolate and differentiate Treg cells from conventional T cells, increasing the accuracy of Treg identification.
• FoxP3: FoxP3 is a specific marker for naturally occurring Treg cells as its expression is associated with the development and function of Treg cells. Foxp3 plays a key role in enhancing and fortifying the molecular attributes of Treg precursor cells, which are beneficial to their functioning and stability, while simultaneously reversing detrimental features that may weaken the effectiveness of Treg cell function.