Final answer:
Regulatory T cells express the surface markers CD4 and CD25, and also the transcription factor FOXP3. They are essential for maintaining immune tolerance and preventing autoimmune diseases by suppressing other T cell immune responses.
Step-by-step explanation:
Regulatory T cells, also known as Treg cells or suppressor T cells, are a subset of T cells that are critical for maintaining immune tolerance and preventing autoimmune diseases. The surface markers found on regulatory T cells are CD4 and CD25.
While helper T cells are also characterized by CD4, regulatory T cells uniquely express CD25 along with the transcription factor FOXP3, which is critical for their function.
These cells play a crucial role in the immune system by suppressing other T cell immune responses, thereby preventing uncontrolled clonal expansion that could lead to autoimmunity and other medical issues.